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Vasopressin Does Not Mediate Hypersensitivity of the Hypothalamic Pituitary Adrenal Axis during Chronic Stress
Author(s) -
Chen Jun,
Young Sharla,
Subburaju Sivan,
Sheppard Jack,
Kiss Alexander,
Atkinson Helen,
Wood Susan,
Lightman Stafford,
Gal Claudine SerradeilLe,
Aguilera Greti
Publication year - 2008
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1410.037
Subject(s) - endocrinology , medicine , adrenocorticotropic hormone , vasopressin , corticosterone , hypothalamic–pituitary–adrenal axis , hypertonic saline , antagonist , corticotropic cell , receptor antagonist , receptor , hormone , pituitary gland
The hypothesis that vasopressin (VP) becomes the main mediator of pituitary corticotroph responsiveness during chronic hypothalamic pituitary adrenal (HPA) axis activation was tested by examining the effect of pharmacologic VP receptor blockade on the adrenocorticotropic hormone (ACTH) and corticosterone responses of 14‐day repeatedly restrained rats. In spite of the increased vasopressinergic activity, repeatedly restrained rats showed lower ACTH and corticosterone responses to 10 min white noise compared with handled controls. These responses were unchanged by injection of the nonpeptide‐selective V1b receptor antagonist SSR149415 i.v., 1 h before noise application. In contrast to noise stress, plasma ACTH responses to i.p. hypertonic saline injection were enhanced in the repeatedly restrained rats compared with handled controls, but responses were also unaffected by SSR149415 administered orally, daily 1 h before restraint. Since SSR149415 effectiveness was low, we used minipump infusion of the peptide V1 receptor antagonist, dGly[Phaa1,D‐tyr(et), Lys, Arg]VP (V1‐Ant) for 14 days, which effectively blocked ACTH responses to exogenous VP. Chronic V1‐Ant infusion reduced plasma ACTH responses to i.p. hypertonic saline in handled controls but not in repeatedly restrained rats. These data suggest that the increased vasopressinergic activity characteristic of chronic stress plays roles other than mediating the hypersensitivity of the HPA axis to a novel stress.