Genetic factors are believed to account for 30-50% of the risk for cocaine and heroin addiction. Dynorphin peptides, derived from the prodynorphin (PDYN) precursor, bind to opioid receptors, preferentially the kappa-opioid receptor, and may mediate the aversive
effects of drugs of abuse. Dynorphin peptides produce place aversion in animals and produce dysphoria in humans. Cocaine and heroin have both been shown to increase expression of PDYN in brain regions relevant for drug reward and use. Polymorphisms in PDYN are therefore hypothesized to increase risk for addiction to drugs of abuse. In this study, 3 polymorphisms in PDYN (rs1022563, rs910080 and rs1997794) were genotyped in opioid-addicted [248 African Americans (AAs) and 1040 European Americans (EAs)], cocaine-addicted (1248 AAs and 336 EAs) and control individuals (674 AAs and 656 EAs). Sex-specific analyses were also performed as a previous study identified PDYN polymorphisms to be more significantly associated with female opioid addicts. We found rs1022563 to be significantly associated with opioid addiction in EAs [P = 0.03, odds ratio (OR) = 1.31; false discovery rate (FDR) corrected q-value]; however, when we performed female-specific association analyses, the OR increased from 1.31 to 1.51. Increased ORs were observed for rs910080 and rs199774 in female opioid addicts also in EAs. No statistically significant associations were observed with cocaine or opioid addiction in AAs. These data show that polymorphisms in PDYN are associated with opioid addiction in EAs and provide further evidence that these risk variants may be more relevant in females.
INTRODUCTION: One of the proposed psychobiological pathways of craving attributes the desire for drinking in the context of tension, discomfort or unpleasant emotions, to "negative" (or "relief") craving. The aim of this study was to replicate a previously reported association of the ... (more)
n style='font-weight:700;'>PDYN rs2281285 variant with negative craving using a different phenotyping approach. METHODS: The TaqMan® Genotyping Assay was used to genotype the rs2281285 variant in 417 German alcohol-dependent subjects. The presence of negative/relief craving was assessed by asking if participants ever ingested alcohol to avoid unwanted emotional or somatic discomfort. RESULTS: The minor allele of rs2281285 was associated with an increased risk of drinking to avoid/escape unwanted emotional or somatic events (OR=2.29, 95% CI=1.08-4.85, p=0.0298). DISCUSSION: Despite the use of a different phenotyping approach to the measurement of negative craving, our results confirm the association between negative craving and PDYN rs2281285. Genetic markers of negative craving may help to identify subgroups of alcohol-dependent individuals vulnerable to relapse in the context of negative emotions or somatic discomfort, leading to the development of specifically tailored treatment strategies.
Dynorphin peptides and the kappa-opioid receptor are important in the rewarding properties of cocaine, heroin, and alcohol. We tested polymorphisms of the prodynorphin gene (PDYN) for association with cocaine dependence and cocaine/alcohol codependence. We genot
yped six single nucleotide polymorphisms (SNPs), located in the promoter region, exon 4 coding, and 3' untranslated region, in 106 Caucasians and 204 African Americans who were cocaine dependent, cocaine/alcohol codependent, or controls. In Caucasians, we found point-wise significant associations of 3'UTR SNPs (rs910080, rs910079, and rs2235749) with cocaine dependence and cocaine/alcohol codependence. These SNPs are in high linkage disequilibrium, comprising a haplotype block. The haplotype CCT was significantly experiment-wise associated with cocaine dependence and with combined cocaine dependence and cocaine/alcohol codependence (false discovery rate, q=0.04 and 0.03, respectively). We investigated allele-specific gene expression of PDYN, using SNP rs910079 as a reporter, in postmortem human brains from eight heterozygous subjects, using SNaPshot assay. There was significantly lower expression for C allele (rs910079), with ratios ranging from 0.48 to 0.78, indicating lower expression of the CCT haplotype of PDYN in both the caudate and nucleus accumbens. Analysis of total PDYN expression in 43 postmortem brains also showed significantly lower levels of preprodynorphin mRNA in subjects having the risk CCT haplotype. This study provides evidence that a 3'UTR PDYN haplotype, implicated in vulnerability to develop cocaine addiction and/or cocaine/alcohol codependence, is related to lower mRNA expression of the PDYN gene in human dorsal and ventral striatum.
Legaki E, etal., In Vivo. 2022 Sep-Oct;36(5):2092-2104. doi: 10.21873/invivo.12935.
BACKGROUND/AIM: Alcohol use disorder (AUD) is a chronic, multifactorial psychiatric condition with an enormous impact on public health and social cost. Genetic studies suggest a heritability, and genome-wide association studies (GWAS) have revealed genetic polymorphisms influencing AUD de
velopment. Our study aimed to investigate known variants located in ADH1B, DRD2, FAAH, SLC39A8, GCKR, and PDYN genes (rs1229984, rs7121986, rs324420, rs13107325, rs1260326, rs2281285 respectively) in an AUD Greek cohort in order to shed more light on the genetic predisposition to AUD. MATERIALS AND METHODS: Alcohol-dependent individuals (n=251) meeting both the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) and the ICD-10 guidelines for alcohol abuse and dependence, and control individuals (n=280) were recruited. DNA was extracted from whole blood and PCR-restriction fragment length polymorphism (RFLP-PCR) or allele-specific PCR method was used for genotyping. RESULTS: Individuals carrying the FAAH rs324420 A allele were significantly associated with increased risk of AUD (p<0.0001). SLC39A8 rs13107325 T allele and ADH1B rs1229984 T allele are overrepresented in control subjects (p<0.0001 and p<0.0001, respectively). The associations are maintained following an adjustment for age and sex and Bonferroni correction. GCKR rs13107325, DRD2 rs7121986, and PDYN rs2281285 polymorphisms did not show a significant association with AUD in the studied population after Bonferroni correction. CONCLUSION: Susceptibility to AUD is related to variations in FAAH, ADH1B, and SLC39A8 genes. These polymorphisms could serve as potential biomarkers for AUD risk.
In this case-control study (423 Turkish subjects), the functional pro-dynorphin (PDYN) 68-bp VNTR polymorphism was genotyped in opioid users receiving sublingual buprenorphine/naloxone treatment (SBNT; n = 129, 119 males and 10 females), in opioid users (OUD; n
= 99, 90 males and 9 females), in alcohol users (AUD; n = 75, 75 males) and in controls (n = 120, 109 males and 11 females) to determine the effect of this polymorphism on different treatment responses, heroin or alcohol dependence as well as age onset of first use. The PDYN 68-bp alleles were determined based on the number of repeats and genotypes were classified as "short/short (SS)", "short-long (SL)" and "long-long (LL)". The intensity of craving, withdrawal, depression and anxiety were measured by the Substance Craving Scale (SCS), the Clinical Opiate Withdrawal Scale (COWS), the Beck Depression Inventory-II (BDI-II) and Beck Anxiety Inventory (BAI), respectively. Healthy controls (5.5 ± 5.8) had significantly lower levels of depressive symptoms compared to OUD (25.4 ± 13.5), AUD (22.5 ± 11.3) and SBNT (19.29 ± 12.2) groups. In OUD group, the LL genotype was associated with decreased intensity of anxiety and depressive symptoms than the SS+SL genotype. The BDI-II scores for PDYN VNTR genotypes within the 4 groups were analysed by two-way ANOVA and statistical differences were found for the groups. SBNT group had significantly lower COWS score than OUD group (1.00 versus 3.00). There were statistically significant differences in the median BAI (11 versus 24) and BDI-II scores (17.5 versus 25) between OUD and SBNT groups, supporting the antidepressant and anxiolytic effects of SBNT in persons with OUD.
Karpyak VM, etal., Int J Neuropsychopharmacol. 2013 Jun;16(5):975-85. doi: 10.1017/S1461145712001137. Epub 2012 Oct 29.
Synthetic κ-opioid receptor (KOR) agonists induce dysphoric and pro-depressive effects and variations in the KOR (OPRK1) and prodynorphin (PDYN) genes have been shown to be associated with alcohol dependence. We genotyped 23 single nucleotide polymorphisms
(SNPs) in the PDYN and OPRK1 genes in 816 alcohol-dependent subjects and investigated their association with: (1) negative craving measured by a subscale of the Inventory of Drug Taking Situations; (2) a self-reported history of depression; (3) the intensity of depressive symptoms measured by the Beck Depression Inventory-II. In addition, 13 of the 23 PDYN and OPRK1 SNPs, which were previously genotyped in a set of 1248 controls, were used to evaluate association with alcohol dependence. SNP and haplotype tests of association were performed. Analysis of a haplotype spanning the PDYN gene (rs6045784, rs910080, rs2235751, rs2281285) revealed significant association with alcohol dependence (p = 0.00079) and with negative craving (p = 0.0499). A candidate haplotype containing the PDYN rs2281285-rs1997794 SNPs that was previously associated with alcohol dependence was also associated with negative craving (p = 0.024) and alcohol dependence (p = 0.0008) in this study. A trend for association between depression severity and PDYN variation was detected. No associations of OPRK1 gene variation with alcohol dependence or other studied phenotypes were found. These findings support the hypothesis that sequence variation in the PDYN gene contributes to both alcohol dependence and the induction of negative craving in alcohol-dependent subjects.
AIMS: The dynorphin (DYN)/Kappa Opioid Receptor (KOR) system has been suggested to be involved in both negative affective states and the action of alcohol. The present study was undertaken to explore whether the DYN/KOR system genes, PDYN and OPRK1, i
nfluence on individual differences in the intensity of depressive symptoms at admission as well as the risk of alcohol use disorder (AUD) risk in a sample of 101 individuals with AUD and 100 controls. METHODS: PDYN (rs2281285, rs2225749 and rs910080) and OPRK1 (rs6473797, rs963549 and rs997917) polymorphisms were analyzed by PCR-RFLP. The intensity of depressive and anxiety symptoms and craving were measured by the Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory (BAI), and Penn Alcohol Craving Scale, respectively. RESULTS: A significant association between the risk of AUD and OPRK1 rs6473797 (P < 0.05) at the gene level. OPRK1 rs6473797 CC genotype was found to lead to a 3.11 times greater alcohol dependence risk. In addition, the BDI-II score of the OPRK1 rs963549 CC genotype was found to be significantly lower (20.9 ± 11.2, min: 1.0, max: 48.0) than that of the CT + TT genotypes (27.04 ± 12.7, min: 0.0, max: 49.0) (t: -2.332, P = 0.022). None of the PDYN polymorphisms were associated with BDI-II score. CONCLUSION: Variations in the KOR are associated with the risk of AUD and the intensity of depressive symptoms at admission at the gene level in Turkish males. On the other hand, PDYN gene seemed not to be associated with AUD, depression, anxiety, and craving.
Phillips RA, etal., bioRxiv [Preprint]. 2023 Aug 21:2023.06.02.543489. doi: 10.1101/2023.06.02.543489.
Neuronal and behavioral adaptations to novel stimuli are regulated by temporally dynamic waves of transcriptional activity, which shape neuronal function and guide enduring plasticity. Neuronal activation promotes expression of an immediate early gene (IEG) program comprised primarily of activity-de
pendent transcription factors, which are thought to regulate a second set of late response genes (LRGs). However, while the mechanisms governing IEG activation have been well studied, the molecular interplay between IEGs and LRGs remain poorly characterized. Here, we used transcriptomic and chromatin accessibility profiling to define activity-driven responses in rat striatal neurons. As expected, neuronal depolarization generated robust changes in gene expression, with early changes (1 h) enriched for inducible transcription factors and later changes (4 h) enriched for neuropeptides, synaptic proteins, and ion channels. Remarkably, while depolarization did not induce chromatin remodeling after 1 h, we found broad increases in chromatin accessibility at thousands of sites in the genome at 4 h after neuronal stimulation. These putative regulatory elements were found almost exclusively at non-coding regions of the genome, and harbored consensus motifs for numerous activity-dependent transcription factors such as AP-1. Furthermore, blocking protein synthesis prevented activity-dependent chromatin remodeling, suggesting that IEG proteins are required for this process. Targeted analysis of LRG loci identified a putative enhancer upstream of Pdyn (prodynorphin), a gene encoding an opioid neuropeptide implicated in motivated behavior and neuropsychiatric disease states. CRISPR-based functional assays demonstrated that this enhancer is both necessary and sufficient for Pdyn transcription. This regulatory element is also conserved at the human PDYN locus, where its activation is sufficient to drive PDYN transcription in human cells. These results suggest that IEGs participate in chromatin remodeling at enhancers and identify a conserved enhancer that may act as a therapeutic target for brain disorders involving dysregulation of Pdyn.
