title: The effect of vasopressin 1b receptor (V1bR) blockade on HPA axis activity in rats exposed to acute heat stress.
abstract: Thermal stressors such as low and high ambient temperature elicit an abundance of neuroendocrine responses including activation of the hypothalamo-pituitary-adrenal (HPA) axis and arginine vasopressin (AVP) release. The exposure to heat is a particularly interesting model for studying AVP action because this kind of stressor represents not only an unpleasant experience but also a threat to osmotic homeostasis. As AVP has long been recognized as a hormone involved in the modulation of HPA axis activity, the aim of this study was to elucidate the role of AVP in acutely heat-exposed rats using Nelivaptan, a selective vasopressin 1b receptor (V1bR) antagonist. Rats were exposed to high ambient temperature (38°C) for 60 min. The circulating hormones were determined by ELISA or chemiluminescence, and intrapituitary adrenocorticotropic hormone (ACTH) and V1bR level were determined by western blot. The results obtained show that V1bR blockade negatively affected the increase in blood ACTH caused by heat exposure. This treatment alone, or in combination with Nelivaptan, decreased intrapituitary V1bR levels while circulating AVP concentration was increased under the same conditions. Furthermore, a strong correlation was observed between blood ACTH and corticosterone concentration. In conclusion, our results directly confirm the positive role of AVP in the regulation of ACTH secretion from the pituitary in animals exposed to heat. Moreover, the results suggest that AVP from the general circulation influences pituitary V1bR.
authors.affiliation: University of Belgrade, Faculty of Biology, Institute for Physiology and Biochemistry, Studentski trg 3, 11000 Belgrade, Serbia. jasnicn@bio.bg.ac.rs
authors.forename: Nebojsa
authors.initials: N
authors.lastname: Jasnic
authors.forename: Jelena
authors.initials: J
authors.lastname: Djordjevic
authors.forename: Predrag
authors.initials: P
authors.lastname: Vujovic
authors.forename: Iva
authors.initials: I
authors.lastname: Lakic
authors.forename: Sinisa
authors.initials: S
authors.lastname: Djurasevic
authors.forename: Gordana
authors.initials: G
authors.lastname: Cvijic
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism; D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000097:blood*; D015153:Blotting, Western; D003345:Corticosterone / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D018869:Heat-Shock Response; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000502:physiology*; D007211:Indoles / Q000494:pharmacology*; D008163:Luminescent Measurements; D008297:Male; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000502:physiology*; D011759:Pyrrolidines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: C456029:1-(5-chloro-1-((2,4-dimethoxyphenyl)sulfonyl)-3-(2-methoxyphenyl)-2-oxo-2,3-dihydro-1H-indol-3-yl)-4-hydroxy-N,N-dimethyl-2-pyrrolidinecarboxamide; D065092:Antidiuretic Hormone Receptor Antagonists; D007211:Indoles; D011759:Pyrrolidines; D001127:Arginine Vasopressin; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone
keywords: SSR149415; adrenocorticotropic hormone; arginine vasopressin; corticosterone; hypothalamo-pituitary–adrenal