Indomethacin prevents the L-NAME-induced increase in plasma levels of oxytocin in dehydrated rats

Inhibiting NO synthase (NOS) with N-G-nitro-L-arginine methyl eater (L-NAME, 250 mu g/5 mu l of artificial cerebrospinal fluid (aCSF)) injected intracerebroventricularly (i.c.v.) increased already enhanced levels of oxytocin, but not vasopressin, in conscious adult male Sprague-Dawley rats dehydrated for 24 h. Intracerebroventricular pretreatment with indomethacin (200 mu g/5 mu l aCSF), an inhibitor of cyclo-oxygenase, but not with losartan (25 mu g/5 mu l aCSF), an antagonist of angiotensin II (ANC II) AT(1)-receptor subtype, nearly prevented the elevation in oxytocin levels after L-NAME. Thus, NO inhibits prostaglandin (but not ANG II) mediated the modulatory actions of NO on oxytocin secretion from the hypothalamo-neurohypophysial system (HNS) during water deprivation. (C) 2000 Elsevier Science BN. All rights reserved.