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N ‐Methyl‐d‐Aspartic Acid Stimulation of Vasopressin Release: Role in Osmotic Regulation and Modulation by Gonadal Steriods
Author(s) -
Swenson Kerry L.,
Badre She E.,
Morsette Delmore J.,
Sladek Celia D.
Publication year - 1998
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1046/j.1365-2826.1998.00257.x
Subject(s) - vasopressin , nmda receptor , medicine , endocrinology , stimulation , arginine vasopressin receptor 1b , receptor , biology , vasopressin receptor , chemistry , antagonist
Previous experiments demonstrated that excitatory amino acids participate in the osmotic regulation of vasopressin secretion, but the specific involvement of N ‐methyl‐ d ‐aspartic acid (NMDA) receptors was not evaluated. This was demonstrated in the present studies. NMDA stimulated vasopressin release from perifused explants of the hypothalamo‐neurohypophyseal system (HNS), and osmotic stimulation of vasopressin release was inhibited by MK‐801 (10 μM) and AP5 (100 μM) NMDA receptor antagonists. The effective concentration of NMDA was dependent upon the Mg 2+ concentration of the perifusate with stimulation observed at 1 μM NMDA in Mg 2+ ‐replete compared with 5 μM in low‐Mg 2+ medium. Previous experiments also demonstrated that estradiol and dihydrotestosterone (DHT) inhibited osmotically stimulated vasopressin secretion, and a nongenomic mechanism of action was suggested by the ability of steroids conjugated to bovine serum albumin to replicate the effect. Experiments were performed to explore the potential role of NMDA receptors in this mechanism. Estradiol (50 pg/ml) and DHT (3 ng/ml) inhibited NMDA stimulated vasopressin release in perifused HNS explants. These results suggest a role of NMDA receptors in the mediation of vasopressin secretion in osmotically stimulated release. Furthermore, estradiol and DHT may exert their inhibitory effect on osmotically stimulated vasopressin release via the NMDA receptor.