RGD Reference Report - Agonist and hypertonic saline-induced trafficking of the NK3-receptors on vasopressin neurons within the paraventricular nucleus of the hypothalamus. - Rat Genome Database
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Agonist and hypertonic saline-induced trafficking of the NK3-receptors on vasopressin neurons within the paraventricular nucleus of the hypothalamus.

Authors: Haley, GE  Flynn, FW 
Citation: Haley GE and Flynn FW, Am J Physiol Regul Integr Comp Physiol. 2006 May;290(5):R1242-50. Epub 2005 Dec 15.
RGD ID: 2305936
Pubmed: (View Article at PubMed) PMID:16357093
DOI: Full-text: DOI:10.1152/ajpregu.00773.2005

The neurokinin 3 receptor (NK3R) is colocalized with vasopressinergic neurons within the hypothalamic paraventricular nucleus (PVN) and intraventricular injections of NK3R agonists stimulate vasopressin (VP) release. Our objectives were to test the hypotheses that intraventricular injections of the selective NK3R agonist, succinyl-[Asp6, N-Me-Phe8] substance P (senktide), activate NK3R expressed by vasopressinergic neurons within the PVN, and see whether NK3R expressed by vasopressinergic neurons in the PVN are activated by hyperosmolarity. NK3R internalization was used as a marker of receptor activation. Immunohistochemistry revealed that NK3Rs were membrane-bound on VP immunoreactive neurons in control rats. Following senktide injection, there was a significant increase in the appearance of NK3R immunoreactivity within the cytoplasm and a morphological rearrangement of the dendrites, indicating receptor internalization, which was reversible. Furthermore, pretreatment with a selective NK3R antagonist, SB-222200, blocked the senktide-induced VP release and internalization of the NK3R in the PVN. These results show that the trafficking of the NK3R is due to ligand binding the NK3R. In a subsequent experiment, rats were administered intragastric loads of 2 or 0.15 M NaCl, and NK3R immunohistochemistry was used to track activation of the receptor. In contrast to control rats, 2 M NaCl significantly increased plasma VP levels and caused the internalization of the NK3R on VP neurons. Also, NK3R immunoreactivity was located in the nuclei of vasopressinergic neurons after senktide and 2 M NaCl treatment. These results show that hyperosmolarity stimulates the local release of an endogenous ligand in the PVN to bind to and activate NK3R on vasopressinergic neurons.

Annotation

Gene Ontology Annotations    

Cellular Component

Objects Annotated

Genes (Rattus norvegicus)
Tacr3  (tachykinin receptor 3)


Additional Information