nd the molecular mechanisms that regulate CRH-BP expression are not well understood. In this study, the rat CRH-BP gene was characterized, and CRH-BP promoter sequences were identified. The rat CRH-BP gene spans almost 12 kilobases and contains 7 exons. Ribonuclease protection experiments indicate that transcription of the CRH-BP gene initiates at multiple sites in rat cerebral cortex. Transfection experiments with CRH-BP-reporter constructs, containing 88-3500 bp 5' flanking and 66 bp 5' untranslated DNA from the rat CRH-BP gene, demonstrate basal promoter activity in multiple cell lines. CRH-BP-reporter constructs also demonstrate positive regulation of promoter activity by cAMP in a variety of cell lines and by CRH in cells expressing the CRH receptor. The DNA sequences between -341 and -88 bp, including the cAMP response element-like sequence at -127 bp, are required for maximal cAMP and CRH regulation of CRH-BP promoter activity. These studies suggest that CRH-BP transcription in vivo may be positively regulated by cAMP and CRH.
Corticotropin-Releasing Hormone (CRH) or Corticotropin-Releasing Factor (CRF) and its family of related naturally occurring endogenous peptides and receptors are becoming recognized for their actions within central (CNS) and peripheral (PNS) nervous systems. It
should be recognized that the term 'CRH' has been displaced by 'CRF' [Guillemin, R., 2005. Hypothalamic hormones a.k.a. hypothalamic releasing factors. J. Endocrinol. 184, 11-28]. However, to maintain uniformity among contributions to this special issue we have used the original term, CRH. The term 'CRF' has been associated recently with CRH receptors and designated with subscripts by the IUPHAR nomenclature committee [Hauger, R.L., Grigoriadis, D.E., Dallman, M.F., Plotsky, P.M., Vale, W.W., Dautzenberg, F.M., 2003. International Union of Pharmacology. XXXVI. Corticotrophin-releasing factor and their ligands. Pharmacol. Rev. 55, 21-26] to denote the type and subtype of receptors activated or antagonized by CRH ligands. CRH, as a hormone, has long been identified as the regulator of basal and stress-induced ACTH release within the hypothalamo-pituitary-adrenal axis (HPA axis). But the concept, that CRH and its related endogenous peptides and receptor ligands have non-HPA axis actions to regulate CNS synaptic transmission outside the HPA axis, is just beginning to be recognized and identified [Orozco-Cabal, L., Pollandt, S., Liu, J., Shinnick-Gallagher, P., Gallagher, J.P., 2006a. Regulation of Synaptic Transmission by CRF Receptors. Rev. Neurosci. 17, 279-307; Orozco-Cabal, L., Pollandt, S., Liu, J., Vergara, L., Shinnick-Gallagher, P., Gallagher, J.P., 2006b. A novel rat medial prefrontal cortical slice preparation to investigate synaptic transmission from amygdala to layer V prelimbic pyramidal neurons. J. Neurosci. Methods 151, 148-158] is especially noteworthy since this synapse has become a prime focus for a variety of mental diseases, e.g. schizophrenia [Fischbach, G.D., 2007. NRG1 and synaptic function in the CNS. Neuron 54, 497-497], and neurological disorders, e.g., Alzheimer's disease [Bell, K.F., Cuello, C.A., 2006. Altered synaptic function in Alzheimer's disease. Eur. J. Pharmacol. 545, 11-21]. We suggest that "The Stressed Synapse" has been overlooked [c.f., Kim, J.J., Diamond, D.M. 2002. The stressed hippocampus, synaptic plasticity and lost memories. Nat. Rev., Neurosci. 3, 453-462; Radley, J.J., Morrison, J.H., 2005. Repeated stress and structural plasticity in the brain. Ageing Res. Rev. 4, 271-287] as a major contributor to many CNS disorders. We present data demonstrating CRH neuroregulatory and neuromodulatory actions at three limbic synapses, the basolateral amygdala to central amygdala synapse; the basolateral amygdala to medial prefrontal cortex synapse, and the lateral septum mediolateral nucleus synapse. A novel stress circuit is presented involving these three synapses. We suggest that CRH ligands and their receptors are significant etiological factors that need to be considered in the pharmacotherapy of mental diseases associated with CNS synaptic transmission.
ggesting that the CRH-BP functions as a negative regulator of CRH activity. Our previous studies have demonstrated sexually dimorphic expression of CRH-BP in the murine pituitary. Basal CRH-BP expression is higher in the female pituitary, where CRH-BP mRNA is detected in multiple anterior pituitary cell types. In this study, we examined stress-induced changes in CRH-BP mRNA and protein expression in mouse pituitary and assessed the in vivo role of CRH-BP in modulating the stress response. Pituitary CRH-BP mRNA was greater than 200-fold more abundant in females than males, and restraint stress increased pituitary CRH-BP mRNA by 11.8-fold in females and 3.2-fold in males as assessed by qRT-PCR. In females, restraint stress increased CRH-BP mRNA levels not only in POMC-expressing cells, but also in PRL-expressing cells. The increase in female pituitary CRH-BP mRNA following stress resulted in significant increases in CRH-BP protein 4-6h after a 30-minute restraint stress as detected by [(125)I]-CRH:CRH-BP cross-linking analyses. Based on this temporal profile, the physiological role of CRH-BP was assessed using a stressor of longer duration. In lipopolysaccharide (LPS) stress studies, female CRH-BP-deficient mice showed elevated levels of stress-induced corticosterone release as compared to wild-type littermates. These studies demonstrate a role for the pituitary CRH-BP in attenuating the HPA response to stress in female mice.
OBJECTIVE: To evaluate the role of corticotrophin-releasing hormone (CRH) in facilitating axon outgrowth. BACKGROUND: Injured neural tissue is difficult to regenerate; the mechanism has not been fully understood. METHODS: A rat model of spinal cord transection i
njury was developed. Levels of BDNF, CRH and oligodendrocyte glycoprotein (OMgp) in injured spinal cord were monitored dynamically after surgery. Cellular interaction among rat dorsal root ganglia (DRG) cells, oligocondrocytes and microglial cells was observed with a coculture model. The axon outgrowth from DRG cells was examined by confocal microscopy. RESULTS: After spinal cord transection, levels of BDNF and CRH increased the next day and decreased afterward, whereas OMgp levels increased from day 3. Administration with BDNF suppressed the levels of OMgp in vitro. The results from a coculture model showed that CRH increased microglial cells to release BDNF; BDNF inhibited OMgp levels in oligodendrocytes and enhanced the axon outgrowth from DRG cells. CONCLUSIONS: This study shows that CRH has the ability to facilitate the outgrowth of axon in spinal neurons, which has therapeutic potential in the treatment of spinal cord injury.
Refojo D and Holsboer F, Ann N Y Acad Sci. 2009 Oct;1179:106-19.
There is an urgent need to generate new drugs or improve existing ones in the pharmacology of mood disorders. The corticotropin-releasing hormone (CRH) system is closely involved in the development and course of depression, and drugs targeting this system arguab
ly offer hope to improve the current tools for drug treatment of depression. Recent clinical studies in depressed patients showed that CRHR1 antagonists improve clinical symptoms of anxiety and depression and reduce stress hormone release following psychosocial stress. These effects of CRHR1 antagonists were not associated with reduced secretory capacity of corticotrophic cells because of CRH receptor abundance at the pituitary level, which contrasts with CRH receptors in the brain. This is in accordance with previous studies showing that CRH injections into the mouse brain activate MAPK pathways in a brain region-specific manner pointing toward differences in signaling pathways beyond the receptor level. We will highlight this and discuss how these brain area-specific differences may offer opportunities for drug discovery. An additional puzzle in the search of new targets for depression is the lack of bona fide animal models helping to discover the antidepressants that are not monoamine based. We recently developed a conditional mouse model that overexpresses CRH in a spatio-temporal-regulated fashion and permits to dissect precisely the contribution of different brain areas to the CRH-dependent behaviors. Recent findings obtained with this mouse model and its usefulness in the context of the CRH-dependent, region-specific changes in depression will be discussed.
The resting EEG is a dynamic index of cortical activation, cognitive function and consciousness and is therefore an intermediate phenotype for many behaviors in which arousal is implicated such as anxiety and alcoholism. We performed a dense whole genome linkage scan using 3878 unlinked SNPs in a la
rge pedigree derived from a population isolate sample of 328 Plains American Indians. Alpha (8-13 Hz), theta (4-8 Hz) and beta (13-30 Hz) EEG power was heritable (0.58-0.27) and stable over a 2 year period (r = 0.82-0.53). Genetic correlations between frequency bands were high (0.75). Linkage peaks for EEG power in all three frequency bands converged on chromosome 5q13-14 with genome-wide significant LOD scores of 3.5 (empirical p<0.0001) for alpha and beta power. A logical candidate gene, corticotropin releasing hormone-binding protein (CRH-BP), was located at the apex of these convergent linkage peaks. CRH-BP was significantly associated with alpha power in the Plains Indians and also in a replication sample of 188 Caucasians. Moreover, the same SNPs and haplotypes, located within the CRH-BP haplotype block, were also associated with anxiety disorders in the Plains Indians and alcohol use disorders in the Caucasians. CRH-BP modulates CRH which influences cortical and hippocampal EEG activity and is the primary mediator of the neuroendocrine stress response. Our results suggest a likely role for CRH-BP in stress-related alcoholism and highlight the use of the resting EEG as an intermediate phenotype for arousal-related behaviors such as anxiety and addiction.
Wong ML, etal., Neuroreport. 1995 Sep 11;6(13):1785-8.
Corticotropin-releasing hormone (CRH) antagonism has neuroprotective effects in models of ischemia. We examined CRH mRNA by in situ hybridization in a well-established rat model of focal cerebral ischemia caused by permanent
middle cerebral artery occlusion (MCAo). In ischemic cortex CRH mRNA levels were elevated 2.6-fold 60 min after MCAo, compared with sham operated animals. CRH mRNA was also induced in the amygdala, 60 min following ischemia, in a pattern which was qualitatively different from that of sham operated animals. This rapid and profound increase in CRH mRNA levels during focal cerebral ischemia is likely to be associated with neurotoxicity, as CRH antagonism has been reported to cause a significant reduction in neuronal loss during ischemia.
Mondal MS, etal., Am J Physiol Gastrointest Liver Physiol. 2003 Jun;284(6):G963-9. Epub 2003 Feb 12.
Neuromedin U (NMU) is a hypothalamic peptide involved in energy homeostasis and stress responses. NMU, when administered intracerebroventricularly, decreases food intake and body weight while increasing body temperature and heat production. In addition, NMU, acting via the corticotropin-releasing ho
rmone (CRH) system, induces gross locomotor activity and stress responses. We studied the effect of intracerebroventricularly administered NMU (0.5-4 nmol) in the regulation of gastric functions in conscious rats. Intracerebroventricular administration of NMU significantly decreased gastric acid output to 30-60% and gastric emptying to 35-70% in a dose-dependent manner. Vagotomy did not abolish the inhibitory effect of NMU on pentagastrin-induced gastric acid secretion. Pretreatment with indomethacin (10 mg/kg), an inhibitor of prostaglandin synthesis, also did not affect NMU-induced acid inhibition. Pretreatment with anti-CRH IgG (1 microg/rat), however, completely blocked NMU-induced acid inhibition (P < 0.01). Administration of yohimbine (4 mg/kg), an alpha(2)-adrenergic receptor antagonist, also abolished NMU-induced acid inhibition (P < 0.01). These findings suggest that NMU is critical in the central regulation of gastric acid secretion via CRH.
Glucocorticoids down-regulate expression of hypothalamic CRH; however, mechanisms by which they do so are not fully understood. The proximal promoter cAMP response element, negative glucocorticoid response element (nGRE), and methylated CpG islands all play a ro
le in crh down-regulation. Dexamethasone (Dex)-repressed crh expression is associated with glucocorticoid receptor (GR) and histone deacetylase 1 (HDAC1) recruitment to the region of the crh promoter. Given that HDAC1 may be present in methylated CpG binding protein 2 (MeCP2) complexes, and that MeCP2 is known to play a role in regulating crh expression, we sought to determine whether or not HDAC1 and/or MeCP2 could interact with the GR. Dex enhanced GR interactions with both proteins. Glucocorticoid regulation of crh has also been associated with CpG methylation; thus we assessed whether GR could interact with a DNA methyltransferase (DnMT). Indeed, the GR interacted with DnMT3b, but not DnMT3a. In addition, Dex-induced occupancy of the crh promoter by HDAC1, MeCP2, and DnMT3b was associated with an increased level of promoter methylation, which appeared to be CpG site specific. Lastly, to extend previous assessment of chromatin modifications in this promoter region, the degree of histone methylation was measured. Dex increased trimethylation of histone 3-lysine 9, a marker of gene suppression; however, levels of di- and trimethylated histone 3-lysine 4, markers of gene activation, were not significantly changed. Taken together, the data suggest that Dex-mediated crh suppression involves formation of a repressor complex consisting of GR, MeCP2, and HDAC1, recruitment of DnMT3b, and associated changes in proximal promoter CpG methylation.
De Souza EB, etal., Ann N Y Acad Sci. 1987;512:237-47.
CRH-IR is significantly reduced in the cerebral cortex of individuals with AD, PD and PSP. Furthermore, we report that the decreases in CRH-IR in AD are accompanied by reciprocal increases in CRH
RH receptors in affected cortical areas. The changes in pre- and postsynaptic markers for CRH are significantly correlated with decrements in ChAT activity. The demonstration of an up regulation of CRH receptors following a decrease in CRH-IR indicates a physiological relevance of the receptor site and is consistent with the concept that CRH acts as a neurotransmitter in normal cortical functions and that disease of this peptidergic systems may be important in certain clinical manifestations of dementia. While the clinical consequences of the changes in CRH in these various disorders are unclear, future therapies directed at increasing CRH levels in brain may prove useful for treatment.
Xiao C, etal., Brain Res. 2006 Feb 16;1073-1074:325-31. Epub 2006 Feb 2.
Behavioral adaptation in aging may become impaired from abnormal expression of amygdalar corticotropin-releasing hormone (CRH) and/or CRH-binding protein (CRH-BP). In this study, we seri
ally sectioned the amygdala in 4-, 12-, and 24-month-old Fischer 344 rats following perfusion with 4% paraformaldehyde. We determined the amount of CRH and CRH-BP containing cells as well as the density of fibers expressing CRH or CRH-BP utilizing densitometric methods. Images were digitized using Zeiss Axiovision software and densitometrically analyzed using Scion Image. Both sides were analyzed in sections cut at 30 mum thickness. Cell counts of CRH-BP containing cells in the basolateral and lateral nucleus of the amygdala were lower in 24-month-old rats vs. 4-month-old rats, respectively (mean cells/section +/- SE): 31 +/- 6 vs. 72 +/- 10 (n = 3; P < 0.05 via ANOVA and Fisher's PLSD). There was a trend for cell counts of CRH containing cells in the central nucleus of the amygdala to be lower in 24-month-old rats vs. 4-month-old rats, respectively 28 +/- 7 vs. 47 +/- 9 (n = 3; P = 0.07 via ANOVA). Densitometric analysis of the number of CRH-BP positive fibers revealed no age differences in CeA; however, with regards to CRH-positive fibers, both 4- and 12-month rats had greater CeA CRH immunoreactivity relative to 24-month-old rats (Ps < 0.05 via ANOVA and Fisher's PLSD). These changes may contribute to impaired adaptations to stress, cognitive decline, and other pathophysiological processes during aging.
The neuropeptides diazepam binding inhibitor (DBI) and corticotropin-releasing hormone (CRH) elicit anxietylike symptoms when administered intracerebroventricularly to laboratory animals. Because of the similarities between the symptoms of certain anxiety states
and the alcohol withdrawal syndrome, we hypothesized that increased secretion of either of these endogenous neuropeptides may, at least in part, be responsible for the symptoms of alcohol withdrawal. We therefore measured DBI and CRH concentrations in cerebrospinal fluid (CSF) of 15 alcohol-dependent patients during acute withdrawal (Day 1) and again at 3 week's abstinence (Day 21). In addition, plasma concentrations of cortisol were measured to evaluate the relationship between pituitary-adrenal axis activation and CSF CRH concentrations. CSF CRH (p < .04), but not CSF DBI, was significantly higher on Day 1 than on Day 21. Although there was a significant decrease in plasma cortisol from Day 1 to Day 21 (p < .001), a significant correlation between CSF CRH and plasma cortisol concentrations was not observed at either time point. Neither CSF neuropeptide correlated with clinical measures of withdrawal severity. These tentative findings may implicate CRH, but not DBI, in the pathogenesis of alcohol withdrawal. Alternately, the central release of CRH and DBI may not be adequately reflected in lumbar CSF.
In addition to regulating the neuroendocrine stress response, corticotropin-releasing hormone (CRH) has been implicated in both normal and pathological behavioral and cognitive responses to stress. CRH-expressing cells and t
heir target neurons possessing CRH receptors (CRF1 and CRF2) are distributed throughout the limbic system, but little is known about the regulation of limbic CRH receptor function and expression, including regulation by the peptide itself. Because CRH is released from limbic neuronal terminals during stress, this regulation might play a crucial role in the mechanisms by which stress contributes to human neuropsychiatric conditions such as depression or posttraumatic stress disorder. Therefore, these studies tested the hypothesis that CRH binding to CRF1 influenced the levels and mRNA expression of this receptor in stress-associated limbic regions of immature rat. Binding capacities and mRNA levels of both CRF1 and CRF2 were determined at several time points after central CRH administration. CRH downregulated CRF1 binding in frontal cortex significantly by 4 h. This transient reduction (no longer evident at 8 h) was associated with rapid increase of CRF1 mRNA expression, persisting for >8 h. Enhanced CRF1 expression-with a different time course-occurred also in hippocampal CA3, but not in CA1 or amygdala, CRF2 binding and mRNA levels were not altered by CRH administration. To address the mechanisms by which CRH regulated CRF1, the specific contributions of ligand-receptor interactions and of the CRH-induced neuronal stimulation were examined. Neuronal excitation without occupation of CRF1 induced by kainic acid, resulted in no change of CRF1 binding capacity, and in modest induction of CRF1 mRNA expression. Furthermore, blocking the neuroexcitant effects of CRH (using pentobarbital) abolished the alterations in CRF1 binding and expression. These results indicate that CRF1 regulation involves both occupancy of this receptor by its ligand, as well as "downstream" cellular activation and suggest that stress-induced perturbation of CRH-CRF1 signaling may contribute to abnormal neuronal communication after some stressful situations.
We have reported that, in rats, hypoxia (10.8% O2) stimulates prolactin (PRL) release from the pituitary. This study is designed to compare the response of pituitary PRL to acute hypoxia (AH), continual hypoxia (CH), intermittent hypoxia (IH), cold, and restraint, individually and combined with hypo
xia. This study also investigates the involvement of the corticotropin-releasing hormone receptor 1 (CRH R1) in the hypoxia-induced PRL response. Hypoxia was induced by exposing the rats to high altitudes of 2 km (16.0% O2) or 5 km (10.8% O2). The PRL levels in the pituitary (iPRL) and in plasma (pPRL) were measured by immunocytochemistry and RIA assay, respectively. The acute hypoxia of 5 km for 2-24 h caused a biphasic change (early decrease and late increase) of PRL. Both CH and IH at 2 or 5 km for 1-5 days markedly increased pPRL but decreased iPRL. Continual severe hypoxia (10.8% O2) for periods of 10, 15, and 25 days significantly enhanced pPRL but this effect was less marked at the lower altitude (16.0% O2) and did not occur during intermittent hypoxia (at both altitudes). The increased pPRL was significantly enhanced by restraint, restraint + hypoxia, hypoxia, and cold + hypoxia exposure. Treatment with a CRH R1 antagonist (CP-154,526) reversed hypoxia-decreased immunoreactive PRL and upregulated PRLmRNA in the pituitary. The data suggest that both CH and IH can stimulate rat PRL release in a time-course- and intensity-dependent manner. However, compared to the relatively low CH-induced response, restraint induced a more powerful response than either cold or hypoxia alone. CRH R1 mediates PRL secretion and PRL mRNA expression in the pituitary under hypoxic exposure. Hypoxia-enhanced PRL response over the lifespan may play a significant role in adaptation to an extreme environment.
Chatzaki E, etal., J Neurochem. 2002 Jan;80(1):81-90. doi: 10.1046/j.0022-3042.2001.00667.x.
Corticotropin-releasing hormone (CRH) is present in the adrenal gland acting as a paracrine factor via stimulation of the locally expressed CRH receptors. In this study, we examined if the adrenal CRH
0;'>CRH system also contains a key component of the neuronal CRH-containing system, the CRH-binding protein (CRH-BP). Our data show that: (i) the CRH-BP transcript is detectable using RT-PCR in total RNA isolated from rat adrenals, and (ii) its protein product is also found by western blot analysis in cell lysates. (iii) Immunohistochemical staining showed that adrenomedullary chromaffin cells produce the bulk of adrenal CRH-BP, an ability retained by the PC12 rat pheochromocytoma cell line. (iv) Regulation of adrenal CRH-BP expression by major modulators of the CRH system was also examined. Protein expression appears to be under the positive control of CRH itself, protein kinase A effector cAMP, glucocorticoids and interleukin (IL)-6. It is thus evident that CRH-BP may play a role in mediating their effects in the adrenal. (v) Differentiation of PC12 into neuron-like cells resulted in a significant increase in CRH-BP, parallel to the induction of the CRH peptide itself. In conclusion, CRH-BP mRNA and protein are present in normal rat adrenomedullary chromaffin cells and in the PC12 rat pheochromocytoma cell line, making the adrenal CRH system directly comparable with those described in the CNS.
Corticotropin-releasing hormone (CRH), known as a key regulator of the hypothalamic-pituitary-adrenal axis response to stress, elicits its biological effects by binding to two membrane receptors (CRH-R1 and CRH
-weight:700;'>CRH-R2). The present studies examined the presence of functional expression of CRH receptors in cultured microglia of rat. CRH-R1 mRNA and protein were detected by reverse transcriptase polymerase chain reaction (RT-PCR), western blotting and receptor chemical cross-linking assay in cultured microglia. CRH-R2 mRNA was undetectable by RT-PCR. The radioligand binding analysis using [125I]Tyr-rat/human CRH revealed a high affinity binding site (Kd of 1.2 nm and Bmax of 84 fmol/mg of protein). Competition studies using CRH and related peptides indicated kinetic and pharmacological characteristics consistent with the CRH-R1 receptor subtype. Receptor chemical cross-linking assay demonstrated a single band of CRH receptor with a molecular weight of -77 kDa, which was inhibited in the presence of excess unlabeled rat/human CRH in a dose-dependent manner and inhibited by a CRH receptor antagonist astressin. Functional coupled cAMP production in cultured microglia was stimulated by exogenous addition of CRH and related peptides in a dose-dependent manner and blocked by astressin. Our findings suggest the functional expression of CRH-R1 receptor in rat microglia, indicating an important mechanism of interaction between immune and neuroendocrine systems in brain physiological and pathological conditions.
Peles E, etal., J Addict Med. 2019 Nov/Dec;13(6):430-435. doi: 10.1097/ADM.0000000000000515.
OBJECTIVES: We have previously shown associations between 4 genetic variants in opioid and stress-related genes (OPRM1, NPYR1/NPYR5, NR3C1, and CRHBP) and prolonged abstinence from heroin without methadone maintenance treatment (MMT). We currently ass
essed the associations between these variants and MMT patients' characteristics. METHODS: A non-selective group of 351 patients who stayed at least 1 year in their first admission to MMT were genotyped and their characteristics and substance in urine on admission and after 1 year were studied. RESULTS: The proportions of patients with both cocaine and benzodiazepine abuse were reduced significantly after 1 year in MMT; however, cocaine abuse cessation was significantly associated with the non-carriers of the CRHBP (corticotrophin releasing hormone binding protein) SNP rs1500 minor C allele (GG genotype) (P = 0.0009, PBonferroni = 0.0221). More carriers of the 2 C alleles (CC genotype) than carriers of the GC and GG genotypes abused cocaine on admission (32.3% vs 19.7%, respectively, P = 0.0414, recessive model), and more of the C allele carriers (GC and CC genotypes) than non-carriers (GG genotype) abused cocaine after 1 year in MMT (25.7% vs 15.8%, respectively, P = 0.0334, dominant model). Abusers of benzodiazepine were more prevalent among carriers of the C allele compared with non-carriers on admission (60.6% vs 45.9%, respectively, P = 0.0080, dominant model), as well as after 1 year in MMT (50.9% vs 39.1%, respectively, P = 0.0362). CONCLUSIONS: Reduction in cocaine abuse among MMT patients may be mediated by a genetic effect in a stress-related gene (CRHBP SNP rs1500 minor C allele). Evaluations of larger samples, additional SNPs, and different populations are needed to support these findings.
Zhou Y, etal., Brain Res Mol Brain Res. 2003 May 26;114(1):73-9.
There is evidence that suggests that increased corticotropin-releasing hormone (CRH) release in the central nucleus of the amygdala underlies the anxiogenic and stress-like consequences of withdrawal that are common in phenomenology to all drugs of abuse. The pr
esent studies were undertaken to determine levels of CRH mRNA in the amygdala, and also in the hypothalamus, frontal cortex and brainstem after short-term (2 days) and intermediate-term (10 days) cocaine withdrawal (with continued saline injections) from chronic (14 days) 'binge' pattern cocaine administration (3 x 15 mg/kg per day at hourly intervals). Confirming our recent finding of an activation of stress responsive hypothalamic-pituitary-adrenal activity during early cocaine withdrawal, there was a significant elevation of plasma corticosterone level after 2-day cocaine withdrawal. There was also a significant elevation of CRH mRNA levels in the amygdala, but not in the hypothalamus, frontal cortex or brainstem after 2-day cocaine withdrawal. A negative correlation between amygdalar CRH mRNA and plasma corticosterone levels was found in the 2-day cocaine withdrawn rats but not in control rats, suggesting that CRH neurons in the amygdala may be differentially responsive to glucocorticoids after chronic cocaine exposure and withdrawal. There were no changes in either plasma corticosterone or amygdalar CRH mRNA levels after 10-day cocaine withdrawal. Our findings of an increase in amygdalar CRH gene expression during early cocaine withdrawal support a potentially important role for amygdalar CRH activity in the anxiogenic and aversive consequences of withdrawal from cocaine during a time when humans are most subject to relapse.
Neuropeptides play important physiological functions during distinct behaviors such as arousal, learning, memory, and reproduction. However, the role of local, extrahypothalamic neuropeptide signaling in shaping synapse formation and neuronal plasticity in the brain is not well understood. Here, we
characterize the spatiotemporal expression profile of the neuropeptide corticotropin-releasing hormone (CRH) and its receptor CRHR1 in the mouse OB throughout development. We found that CRH-expressing interneurons are present in the external plexiform layer, that its cognate receptor is expressed by granule cells, and show that both CRH and CRHR1 expression enriches in the postnatal period when olfaction becomes important towards olfactory-related behaviors. Further, we provide electrophysiological evidence that CRHR1-expressing granule cells functionally respond to CRH ligand, and that the physiological circuitry of CRHR1 knockout mice is abnormal, leading to impaired olfactory behaviors. Together, these data suggest a physiologically relevant role for local CRH signaling towards shaping the neuronal circuitry within the mouse OB.
Stanley SA, etal., Am J Physiol Endocrinol Metab. 2004 Sep;287(3):E583-90. doi: 10.1152/ajpendo.00576.2003. Epub 2004 May 11.
Cocaine- and amphetamine-regulated transcript (CART) was originally isolated from rat brain, but CART is also synthesized and stored in the anterior pituitary. The localization of pituitary CART and factors regulating its synthesis are largely unknown. The regulation of pituitary CART synthesis and
release in response to CRH and glucocorticoids was examined in vitro and in vivo. CART immunoreactivity (CART-IR) was released from anterior pituitary segments. This release was increased 15-fold in response to corticotropin-releasing hormone (CRH). Intraperitoneal administration of CRH to rats significantly increased plasma CART-IR. Furthermore, CART-IR content and plasma CART-IR were significantly increased in adrenalectomized rats, and anterior pituitary CART mRNA expression, CART-IR content, and plasma CART-IR were significantly decreased in corticosterone-treated rats. Plasma CART-IR showed a pattern of diurnal variation similar to that of ACTH and corticosterone, and plasma CART-IR was positively correlated with corticosterone. CART-IR was detectable in the medium of the corticotroph cell line AtT-20. Dual in situ hybridization for prepro-CART (ppCART) mRNA expression and immunocytochemistry for ACTH showed localization of ppCART mRNA to a subpopulation of ACTH-immunoreactive cells. These findings demonstrate that pituitary CART expression and release are regulated by CRH and the glucocorticoid environment and that pituitary CART is partly localized to corticotrophs.
Ray LA, Alcohol Clin Exp Res. 2011 Jan;35(1):166-74. doi: 10.1111/j.1530-0277.2010.01333.x. Epub 2010 Oct 6.
BACKGROUND: Neurobiological theories of addiction have highlighted disruption in stress pathways as a central feature of addictive disorders, and pharmacological treatments targeting stress mechanisms hold great promise. This study examines genetic determinants of stress-induced and cue-i
nduced craving in heavy drinkers by testing single-nucleotide polymorphisms (SNPs) of the corticotrophin-releasing hormone binding protein (CRH-BP) gene and the mu-opioid receptor (OPRM1) gene. METHODS: This study combines guided imagery stress exposure and in vivo alcohol cue exposure in a sample of 64 (23 women) non-treatment-seeking heavy drinkers. RESULTS: Analyses, uncorrected for multiple comparisons, revealed that a tag SNP of the CRH-BP gene (rs10055255) moderated stress-induced craving in this sample. The same SNP predicted greater affective responses to the stress manipulation, including greater levels of subjective tension and negative mood. The Asp40 allele of the OPRM1 was associated with greater cue-induced alcohol craving following the neutral imagery condition. CONCLUSIONS: These initial results extend recent preclinical and clinical findings implicating the CRH-BP in stress-related alcoholism and confirm the role of the Asp40 allele of the OPRM1 gene in reward-driven alcohol phenotypes. Human laboratory models of stress and cue-induced craving may be useful in pharmacotherapy development targeting dysregulation of stress systems. Larger studies are needed to validate these preliminary findings, which should also be extended to clinical samples.
Toorie AM, etal., J Biol Chem. 2016 Mar 11;291(11):5844-59. doi: 10.1074/jbc.M115.675264. Epub 2016 Jan 11.
Understanding the role of hypothalamic neuropeptides and hormones in energy balance is paramount in the search for approaches to mitigate the obese state. Increased hypothalamic-pituitary-adrenal axis activity leads to increased levels of glucocorticoids (GC) that are known to regulate body weight.
The axis initiates the production and release of corticotropin-releasing hormone (CRH) from the paraventricular nucleus (PVN) of the hypothalamus. Levels of active CRH peptide are dependent on the processing of its precursor pro-CRH by the action of two members of the family of prohormone convertases 1 and 2 (PC1 and PC2). Here, we propose that the nutrient sensor sirtuin 1 (Sirt1) regulates the production of CRH post-translationally by affecting PC2. Data suggest that Sirt1 may alter the preproPC2 gene directly or via deacetylation of the transcription factor Forkhead box protein O1 (FoxO1). Data also suggest that Sirt1 may alter PC2 via a post-translational mechanism. Our results show that Sirt1 levels in the PVN increase in rats fed a high fat diet for 12 weeks. Furthermore, elevated Sirt1 increased PC2 levels, which in turn increased the production of active CRH and GC. Collectively, this study provides the first evidence supporting the hypothesis that PVN Sirt1 activates the hypothalamic-pituitary-adrenal axis and basal GC levels by enhancing the production of CRH through an increase in the biosynthesis of PC2, which is essential in the maturation of CRH from its prohormone, pro-CRH.
Tadavarty R, etal., Neurosci Lett. 2015 Oct 8;606:145-50. doi: 10.1016/j.neulet.2015.08.049. Epub 2015 Sep 7.
We investigated the anti-nociceptive effects of GABA-C receptors in the central nervous system. Intracisternal injection of CACA, a GABA-C receptor agonist or isoguvacine, a GABA-A receptor agonist, significantly increased the tail-withdrawal latency. TPMPA, a GABA-C receptor antagonist blocked the
effects of CACA but not isoguvacine indicating that GABA-C receptors are involved in regulating pain. Further, double-labelled immunofluorescence studies revealed that GABA-Crho2 receptors are expressed presynaptically in the spinal dorsal horn, especially, substantia gelatinosa, a region that has been previously implicated in analgesia by regulating nociceptive inflow. These data provide a provenance for future work looking at presynaptic spinal GABA-C receptors in the control of nociception.
Musculoskeletal pain (MSP) is a common sequela of traumatic stress exposure. While biological factors contributing to chronic MSP after motor vehicle collision (MVC) have traditionally focused on tissue injury, increasing evidence suggests that neuro/stress/immune processes mediated by stress syste
m activation may play a more dominant role. In a previous study, we found that genetic variants in the hypothalamic-pituitary-adrenal (HPA) axis-related gene FKBP5 influence vulnerability to persistent MSP 6 weeks after MVC. In the present cohort study (n = 855), we evaluated whether genetic variants in several other important HPA axis-related genes, including the glucocorticoid receptor (NR3C1), corticotropin-releasing hormone receptor R1 (CRHR1), and corticotropin-releasing hormone-binding protein (CRHBP), influence risk of chronic MSP over time after MVC. Genetic polymorphism rs7718461 in the CRHBP gene showed significant association (P = 0.0012) with overall pain severity during the year after MVC in regression models controlling for multiple comparisons. Two additional CRHBP alleles in high linkage disequilibrium with rs7718461 also showed trend-level significance. In secondary analyses, a significant interaction between this CRHBP locus (minor allele frequency = 0.33) and time was observed (P = 0.015), with increasing effect observed over time following trauma. A significant CRHBP x FKBP5 interaction was also observed, with substantially increased MSP after MVC in those with a risk allele in both genes compared with either gene alone. The results of this study indicate that genetic variants in 2 different HPA axis genes predict chronic MSP severity following MVC and support the hypothesis that the HPA axis is involved in chronic post-MVC MSP pathogenesis.
Corticotropin-releasing hormone (Crh), a 41-residue polypeptide, activates two G-protein-coupled receptors, Crhr1 and Crhr2, causing (among other transductional events) phosphorylation o
f the transcription factor Creb. The physiologic role of these receptors is only partially understood. Here we report that male, but not female, Crhr2-deficient mice exhibit enhanced anxious behaviour in several tests of anxiety in contrast to mice lacking Crhr1. The enhanced anxiety of Crhr2-deficient mice is not due to changes in hypothalamic-pituitary-adrenal (HPA) axis activity, but rather reflects impaired responses in specific brain regions involved in emotional and autonomic function, as monitored by a reduction of Creb phosphorylation in male, but not female, Crhr2-/- mice. We propose that Crhr2 predominantly mediates a central anxiolytic response, opposing the general anxiogenic effect of Crh mediated by Crhr1. Neither male nor female Crhr2-deficient mice show alterations of baseline feeding behaviour. Both respond with increased edema formation in response to thermal exposure, however, indicating that in contrast to its central role in anxiety, the peripheral role of Crhr2 in vascular permeability is independent of gender.
Sillaber I, etal., Science 2002 May 3;296(5569):931-3.
There is a relation between stress and alcohol drinking. We show that the corticotropin-releasing hormone (CRH) system that mediates endocrine and behavioral responses to stress plays a role in the control of long-term alcohol drinking. In mice lacking a functio
nal CRH1 receptor, stress leads to enhanced and progressively increasing alcohol intake. The effect of repeated stress on alcohol drinking behavior appeared with a delay and persisted throughout life. It was associated with an up-regulation of the N-methyl-d-aspartate receptor subunit NR2B. Alterations in the CRH1 receptor gene and adaptional changes in NR2B subunits may constitute a genetic risk factor for stress-induced alcohol drinking and alcoholism.
Schafer C, etal., Am J Physiol Gastrointest Liver Physiol 2003 Oct;285(4):G726-34. Epub 2003 Jun 11.
Ca2+-regulated heat-stable protein of 24 kDa (CRHSP-24) is a serine phosphoprotein originally identified as a physiological substrate for the Ca2+-calmodulin regulated protein phosphatase calcineurin (PP2B). CRHSP-24 is a pa
ralog of the brain-specific mRNA-binding protein PIPPin and was recently shown to interact with the STYX/dead phosphatase protein in developing spermatids (Wishart MJ and Dixon JE. Proc Natl Acad Sci USA 99: 2112-2117, 2002). Investigation of the effects of phorbol ester (12-o-tetradecanoylphorbol-13-acetate; TPA) and cAMP analogs in 32P-labeled pancreatic acini revealed that these agents acutely dephosphorylated CRHSP-24 by a Ca2+-independent mechanism. Indeed, cAMP- and TPA-mediated dephosphorylation of CRHSP-24 was fully inhibited by the PP1/PP2A inhibitor calyculin A, indicating that the protein is regulated by an additional phosphatase other than PP2B. Supporting this, CRHSP-24 dephosphorylation in response to the Ca2+-mobilizing hormone cholecystokinin was differentially inhibited by calyculin A and the PP2B-selective inhibitor cyclosporin A. Stimulation of acini with secretin, a secretagogue that signals through the cAMP pathway in acini, induced CRHSP-24 dephosphorylation in a concentration-dependent manner. Isoelectric focusing and immunoblotting indicated that elevated cellular Ca2+ dephosphorylated CRHSP-24 on at least three serine sites, whereas cAMP and TPA partially dephosphorylated the protein on at least two sites. The cAMP-mediated dephosphorylation of CRHSP-24 was inhibited by low concentrations of okadaic acid (10 nM) and fostriecin (1 microM), suggesting that CRHSP-24 is regulated by PP2A or PP4. Collectively, these data indicate that CRHSP-24 is regulated by diverse and physiologically relevant signaling pathways in acinar cells, including Ca2+, cAMP, and diacylglycerol.
Wang X, etal., Mol Neurobiol. 2013 Dec;48(3):544-55. doi: 10.1007/s12035-013-8444-4. Epub 2013 Mar 26.
Stress during gestation increases vulnerability to disease and changes behavior in offspring. We previously reported that hypoxia and restraint during pregnancy sensitized the hypothalamic-pituitary-adrenal (HPA) axis and induced anxiety-like behavior in the adult offspring. Here, we report that ge
stational intermittent hypoxia (GIH) elicited a sex-dependent anxiety-like behavior in male P90 offspring and activation of corticotropin-releasing hormone (CRH) and CRH type-1 receptor (CRHR1) mRNA in the hypothalamic paraventricular nucleus (PVN) and in male E19 hypothalamus. These linked to demethylation at several specific sites of CpG island of Crhr1 promoter in P90 PVN and E19 embryo hypothalamus in GIH groups. Crhr1 DNA demethylation is more crucial in CpG island 1 than island 2 for activation of CRHR1 mRNA. DNMT3b is required for the Crhr1 DNA methylation than DNMT1 and DNMT3a in increased CRHR1 mRNA. We first address a novel hypothesis that GIH-induced male-sex-dependent demethylation at CpG sites of Crhr1 DNA in promoter triggers elevation of CRHR1 mRNA in PVN and anxiety-like behavior in adult offspring.
Kim WJ, etal., Respirology. 2009 Mar;14(2):260-3. doi: 10.1111/j.1440-1843.2008.01425.x. Epub 2008 Dec 11.
BACKGROUND AND OBJECTIVE: Inhaled corticosteroids are used to treat COPD and asthma. An association between sequence variants in the corticotrophin-releasing hormone receptor 1 (CRHR1) gene and improved lung function in asthmatics treated with inhaled
corticosteroids was reported recently. This study investigated the association between the change in lung function in response to inhaled corticosteroids and single-nucleotide CRHR1 polymorphisms in patients with COPD. METHODS: COPD patients (n = 87) with a positive smoking history were recruited from the pulmonary clinics of 11 hospitals in Korea. Patients were treated with fluticasone propionate and salmeterol for 12 weeks and lung function was measured at baseline and after the 12-week treatment. Eighty-four of the 87 subjects were successfully genotyped. RESULTS: Seventy-one patients with the wild-type GG genotype and 13 patients with the heterozygous GT genotype in rs242 941 were evaluated. After 12-week treatment, the change in FEV(1) was significantly higher in patients with wild-type GG genotype (6.0 +/- 0.8% of predicted FEV(1)) than in GT heterozygotes (-0.8 +/- 1.8, P = 0.003). CONCLUSIONS: Improved FEV(1) following inhaled corticosteroid and a long-acting beta2-agonist was associated with CRHR1 genetic polymorphism in patients with COPD.
Corticosteroids mediate a variety of immunological actions and are commonly utilized in the treatment of a wide range of diseases. Unfortunately, therapy with this class of medications is associated with a large proportion of non-responders and significant side effects. Inhaled corticosteroids are t
he most commonly used asthma controller therapy. However, asthmatic response to corticosteroids also varies widely between individuals. We investigated the genetic contribution to the variation in response to inhaled corticosteroid therapy in asthma. The association of longitudinal change in lung function and single nucleotide polymorphisms from candidate genes crucial to the biologic actions of corticosteroids were evaluated in three independent asthmatic clinical trial populations utilizing inhaled corticosteroids as the primary therapy in at least one treatment arm. Variation in one gene, corticotropin-releasing hormone receptor 1 (CRHR1) was consistently associated with enhanced response to therapy in each of our three populations. Individuals homozygous for the variants of interest manifested a doubling to quadrupling of the lung function response to corticosteroids compared with lack of the variants (P-values ranging from 0.006 to 0.025 for our three asthmatic populations). As the primary receptor mediating the release of adrenocorticotropic hormone, which regulates endogenous cortisol levels, CRHR1 plays a pivotal, pleiotropic role in steroid biology. These data indicate that genetic variants in CRHR1 have pharmacogenetic effects influencing asthmatic response to corticosteroids, provide a rationale for predicting therapeutic response in asthma and other corticosteroid-treated diseases, and suggests this gene pathway as a potential novel therapeutic target.
The corticotropin-releasing hormone receptor type 1 (CRHR1) plays an important role in orchestrating neuroendocrine, behavioral, and autonomic responses to stress. To identify molecules capable of directly modulating CRHR1 s
ignaling, we performed a yeast-two-hybrid screen using the C-terminal intracellular tail of the receptor as bait. We identified several members of the membrane-associated guanylate kinase (MAGUK) family: postsynaptic density protein 95 (PSD95), synapse-associated protein 97 (SAP97), SAP102 and membrane associated guanylate kinase, WW and PDZ domain containing 2 (MAGI2). CRHR1 is co-expressed with the identified MAGUKs and with the additionally investigated PSD93 in neurons of the adult mouse brain and in primary hippocampal neurons, supporting the probability of a physiological interaction in vivo. The C-terminal PDZ (PSD-95, discs large, zona occludens 1) binding motif of CRHR1 is essential for its physical interaction with MAGUKs, as revealed by the CRHR1-STAVA mutant, which harbors a functionally impaired PDZ binding motif. The imitation of a phosphorylation at Thr413 within the PDZ binding motif also disrupted the interaction with MAGUKs. In contrast, distinct PDZ domains within the identified MAGUKs are involved in the interactions. Expression of CRHR1 in primary neurons demonstrated its localization throughout the neuronal plasma membrane, including the excitatory post synapse, where the receptor co-localized with PSD95 and SAP97. The co-expression of CRHR1 and respective interacting MAGUKs in HEK293 cells resulted in a clustered subcellular co-localization which required an intact PDZ binding motif. In conclusion, our study characterized the PDZ binding motif-mediated interaction of CRHR1 with multiple MAGUKs, which directly affects receptor function.
Awasthi S, etal., Indian J Pediatr. 2015 Sep;82(9):781-6. doi: 10.1007/s12098-015-1702-x. Epub 2015 Feb 26.
OBJECTIVE: To determine association of corticotrophin releasing hormone receptor 1 (CRHR1) gene single nucleotide polymorphisms (SNPs), rs242939 (A>G) and rs242941 (G>T) with response to systemic corticosteroids in North Indian asthmatic children during acute e
xacerbation. METHODS: This was a hospital based cross-sectional study. Sixty-eight children aged 1 to 12 y with acute exacerbation of asthma were included in the study. The study was approved by the institutional ethics committee and written informed consent was obtained from parents/guardians of recruited children. GINA guidelines 2008, were used for classification and treatment of acute exacerbation of asthma. As per the GINA guidelines 2008, children who had good response to injectable corticosteroid were classified as "Corticosteroid Responders" (CR). Rest of the children with incomplete or poor response to injectable corticosteroid were classified as "Corticosteroid Non Responders" (CNR). RESULTS: Among 68 hospitalized children, 45 (66.17 %) children were CR whereas 23 (33.83 %) children were CNR. On analyzing as dominant model, children with one or two copies of mutant allele of SNP rs242941 had statistically significant better response to systemic corticosteroid (OR = 5.00; 95 %CI = 1.32-19.64; p 0.013) as compared to children with no mutant allele. CONCLUSIONS: Thus, CRHR1 gene SNP rs242941 polymorphism is associated with better response to systemic corticosteroid during acute exacerbation of asthma.
Szczepankiewicz A, etal., Psychiatr Genet. 2013 Dec;23(6):239-46. doi: 10.1097/YPG.0000000000000007.
OBJECTIVE: Genes involved in the regulation of the hypothalamus-pituitary-adrenal axis are responsible for altered susceptibility to mood disorders. The aim of this study was to analyze the possible association of CRHR1 and AVPR1b gene variants with bipolar diso
rder and major depressive disorder (MDD). METHODS: In the study, we included 486 patients with bipolar disorder and 215 patients with MDD. Consensus diagnosis was made according to Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) criteria, using the Structured Clinical Interview for DSM Disorders. The control group consisted of 712 healthy participants. Genotyping of CRHR1 and AVPR1b polymorphisms was performed using TaqMan single nucleotide polymorphism genotyping assays. Linkage disequilibrium analysis was carried out on Haploview. Gene-gene interactions were analyzed using the multifactor dimensionality reduction method. RESULTS: By single marker analysis we have found an association of rs28536160 of AVPR1b and rs4076452 and rs16940655 of CRHR1 with mood disorders (P=0.036, 0.0013, and 0.003, respectively). We observed strong linkage disequilibrium between seven CRHR1 polymorphisms grouped in two haplotype blocks; however, none of them showed an association with MDD or bipolar disorder. Similarly, no association was found for three of four strongly linked AVPR1b polymorphisms. Gene-gene interaction analysis revealed a significant epistatic interaction between AVPR1b and CRHR1 genes in susceptibility to MDD (P=0.017). CONCLUSION: Polymorphisms of CRHR1 and AVPR1b may modify susceptibility to mood disorders.
Thomas DD, etal., J Biol Chem 2002 Sep 20;277(38):35496-502.
CRHSP-28 is a member of the tumor protein D52 protein family that was recently shown to regulate Ca(2+)-stimulated secretory activity in streptolysin-O-permeabilized acinar cells (Thomas, D. H., Taft, W. B., Kaspar, K. M., and Groblewski, G. E. (2001) J. Biol. C
hem. 276, 28866-28872). In the present study, the Ca(2+)-sensitive phospholipid-binding protein annexin VI was purified from rat pancreas as a CRHSP-28-binding protein. The interaction between CRHSP-28 and annexin VI was demonstrated by coimmunoprecipitation and gel-overlay assays and was shown to require low micromolar levels of free Ca(2+), indicating these molecules likely interact under physiological conditions. Immunofluorescence microscopy confirmed a dual localization of CRHSP-28 and annexin VI, which appeared in a punctate pattern in the supranuclear and apical cytoplasm of acini. Stimulation of cells for 5 min with the secretagogue cholecystokinin enhanced the colocalization of CRHSP-28 and annexin VI within regions of acini immediately below the apical plasma membrane. Tissue fractionation revealed that CRHSP-28 is a peripheral membrane protein that is highly enriched in smooth microsomal fractions of pancreas. Further, the content of CRHSP-28 in microsomes was significantly reduced in pancreatic tissue obtained from rats that had been infused with a secretory dose of cholecystokinin for 40 min, demonstrating that secretagogue stimulation transiently alters the association of CRHSP-28 with membranes in cells. Collectively, the Ca(2+)-dependent binding of CRHSP-28 and annexin VI, together with their colocalization in the apical cytoplasm, is consistent with a role for these molecules in acinar cell membrane trafficking events that are essential for digestive enzyme secretion.
There is growing evidence that brooding rumination plays a key role in the intergenerational transmission of major depressive disorder (MDD) and may be an endophenotype for depression risk. However, less is known about the mechanisms underlying this role. Therefore, the goal of the current study was
to examine levels of brooding in children of mothers with a history of MDD (n = 129) compared to children of never depressed mothers (n = 126) and to determine whether the variation in a gene known to influence hypothalamic-pituitary-adrenal axis functioning--corticotropin-releasing hormone receptor 1 (CRHR1)--would moderate the link between maternal MDD and children's levels of brooding. We predicted children of mothers with a history of MDD would exhibit higher levels of brooding than children of mothers with no lifetime depression history but that this link would be stronger among children carrying no copies of the protective CRHR1 TAT haplotype. Our results supported these hypotheses and suggest that the development of brooding among children of depressed mothers, particularly children without the protective CRHR1 haplotype, may serve as an important mechanism of risk for the intergenerational transmission of depression.
Leszczyńska-Rodziewicz A, etal., Psychiatry Res. 2013 May 15;207(1-2):140-2. doi: 10.1016/j.psychres.2012.09.025. Epub 2012 Oct 12.
The present study included 130 patients with melancholic depression in the course of bipolar disorder and 732 healthy controls. No association was found for alleles, genotypes, or haplotype analysis for NR3C1, AVPR1b, and CRHR1 genes and melancholic depression.
We studied seven genes that reflect events relevant to antidepressant action at four sequential levels: (1) entry into the brain, (2) binding to monoaminergic transporters, and (3) distal effects at the transcription level, resulting in (4) changes in neurotrophin and neuropeptide receptors. Those g
enes are ATP-binding cassette subfamily B member 1 (ABCB1), the noradrenaline, dopamine, and serotonin transporters (SLC6A2, SLC6A3 and SLC6A4), cyclic AMP-responsive element binding protein 1 (CREB1), corticotropin-releasing hormone receptor 1 (CRHR1) and neurotrophic tyrosine kinase type 2 receptor (NTRK2). Sequence variability for those genes was obtained in exonic and flanking regions. A total of 56 280 000 bp across were sequenced in 536 unrelated Mexican Americans from Los Angeles (264 controls and 272 major depressive disorder (MDD)). We detected in those individuals 419 single nucleotide polymorphisms (SNPs); the nucleotide diversity was 0.00054 + or - 0.0001. Of those, a total of 204 novel SNPs were identified, corresponding to 49% of all previously reported SNPs in those genes: 72 were in untranslated regions, 19 were in coding sequences of which 7 were non-synonymous, 86 were intronic and 27 were in upstream/downstream regions. Several SNPs or haplotypes in ABCB1, SLC6A2, SLC6A3, SLC6A4, CREB1 and NTRK2 were associated with MDD, and in ABCB1, SLC6A2 and NTRK2 with antidepressant response. After controlling for age, gender and baseline 21-item Hamilton Depression Rating Scale (HAM-D21) score, as well as correcting for multiple testing, the relative reduction of HAM-D21 score remained significantly associated with two NTRK2-coding SNPs (rs2289657 and rs56142442) and the haplotype CAG at rs2289658 (splice site), rs2289657 and rs2289656. Further studies in larger independent samples will be needed to confirm these associations. Our data indicate that extensive assessment of sequence variability may contribute to increase understanding of disease susceptibility and drug response. Moreover, these results highlight the importance of direct re-sequencing of key candidate genes in ethnic minority groups in order to discover novel genetic variants that cannot be simply inferred from existing databases.
Anxiety and affective disorders are often associated with hypercortisolism and dysfunctional serotonergic systems, including increased expression of TPH2, the gene encoding the rate-limiting enzyme of neuronal serotonin synthesis. We previously reported that chronic glucocorticoid exposure is anxiog
enic and increases rat Tph2 mRNA expression, but it was still unclear if this also translates to increased TPH2 protein levels and in vivo activity of the enzyme. Here, we found that adult male rats treated with corticosterone (CORT, 100 mug/ml) via the drinking water for 21 days indeed show increased TPH2 protein expression in the dorsal and ventral part of the dorsal raphe nucleus (DRD, DRV) during the light phase, abolishing the enzyme's diurnal rhythm. In a second study, we systemically blocked the conversion of 5-hydroxytryptophan (5-HTP) to serotonin immediately before rats treated with CORT or vehicle were either exposed to 30 min acoustic startle stress or home cage control conditions. This allowed us to measure 5-HTP accumulation as a direct readout of basal versus stress-induced in vivo TPH2 activity. As expected, basal TPH2 activity was elevated in the DRD, DRV and MnR of CORT-treated rats. In response to stress, a multitude of serotonergic systems reacted with increased TPH2 activity, but the stress-, anxiety-, and learned helplessness-related dorsal and caudal DR (DRD/DRC) displayed stress-induced increases in TPH2 activity only after chronic CORT-treatment. To address the mechanisms underlying this region-specific CORT-dependent sensitization, we stereotaxically implanted CORT-treated rats with cannulae targeting the DR, and pharmacologically blocked either corticotropin-releasing hormone receptor type 1 (CRHR1) or type 2 (CRHR2) 10 min prior to acoustic startle stress. CRHR2 blockade prevented stress-induced increases of TPH2 activity within the DRD/DRC, while blockade of CRHR1 potentiated stress-induced TPH2 activity in the entire DR. Stress-induced TPH2 activity in the DRD/DRC furthermore predicted TPH2 activity in the amygdala and in the caudal pontine reticular nucleus (PnC), while serotonin synthesis in the PnC was strongly correlated with the maximum startle response. Our data demonstrate that chronically elevated glucocorticoids sensitize stress- and anxiety-related serotonergic systems, and for the first time reveal competing roles of CRHR1 and CRHR2 on stress-induced in vivo serotonin synthesis.
Roy A, etal., J Psychiatr Res. 2012 Jan;46(1):72-9. doi: 10.1016/j.jpsychires.2011.09.009. Epub 2011 Oct 5.
Childhood trauma is associated with hypothalamic-pituitary-adrenal (HPA) axis dysregulation. Both factors increase risk for suicidal behavior. Corticotropin releasing hormone (CRH) regulates the HPA axis and its actions are moderated by a high-affinity binding p
rotein (CRHBP). We hypothesized that CRHBP variation and interaction with childhood trauma might influence suicidal behavior. Moreover, there might be an additive effect with FKPB5, another HPA axis gene previously associated with suicidality in this dataset. African Americans were recruited: 398 treatment seeking patients with substance dependence (90% men; 120 suicide attempters) and 432 non-substance dependent individuals (40% men; 21 suicide attempters). A total of 474 participants (112 suicide attempters) completed the Childhood Trauma Questionnaire (CTQ). Haplotype-tagging SNPs were genotyped across CRHBP and, for completeness, across CRH, CRHR1 and CRHR2. FKBP5 genotypes were available. Three CRHBP SNPs rs6453267, rs7728378 and rs10474485 showed a nominally significant interaction with the continuous CTQ score to predict suicide attempt; rs7728378 remained significant after FDR correction. There was an additive effect with FKBP5: in the group exposed to high trauma, the prevalence of suicide attempt was 0.35-0.30 in carriers of either the FKBP5 rs3800373 major homozygote or the CRHBP rs7728378 major homozygote and 0.58 in carriers of both major homozygotes. Individuals without either major homozygote were resilient to the effects of childhood trauma (suicide attempt prevalence 0.24). Main effects of CRHBP rs6453267 and CRHR1 rs9900679, both unique to African ancestry, were detected. CRHBP variation may predispose, independently and additively, to suicidal behavior in individuals who have experienced childhood trauma.
Hansson AC, etal., Proc Natl Acad Sci U S A. 2006 Oct 10;103(41):15236-41. Epub 2006 Oct 2.
Alcoholism is a chronic relapsing disorder with substantial heritability. Uncovering gene-environment interactions underlying this disease process can aid identification of novel treatment targets. Here, we found a lowered threshold for stress-induced reinstatement of alcohol seeking in Marchigian-S
ardinian Preferring (msP) rats genetically selected for high alcohol preference. In situ hybridization for a panel of 20 stress-related genes in 16 brain regions was used to screen for differential gene expression that may underlie this behavioral phenotype. An innate up-regulation of the Crhr1 transcript, encoding the corticotropin-releasing hormone receptor 1 (CRH-R1), was found in several limbic brain areas of msP rats genetically selected for high alcohol preference, was associated with genetic polymorphism of the Crhr1 promoter, and was accompanied by increased CRH-R1 density. A selective CRH-R1 antagonist (antalarmin, 10-20 mg/kg) was devoid of effects on operant alcohol self-administration in unselected Wistar rats but significantly suppressed this behavior in the msP line. Stress-induced reinstatement of alcohol seeking was not significantly affected by antalarmin in Wistar rats but was fully blocked in msP animals. These data demonstrate that Crhr1 genotype and expression interact with environmental stress to reinstate alcohol-seeking behavior.
