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N-methyl-D-aspartate receptor involvement in dexamethasone and stress-induced hypothalamic somatostatin release in
C Estupina1, J Abarca, S Arancibia
1Laboratoire Plasticite et Adaptation Cellulaires, ERS 5644 du CNRS, Université Montpellier 2, France.
Abstract:
The median eminence (ME) push-pull perfusion technique was used in this work and the results clearly showed that i.p. administration of MK-801 (4 mg/kg), a specific N-methyl-D-aspartate (NMDA) receptor antagonist, totally abolished dexamethasone (Dex) (300 micrograms/ 100 g i.p. injected) and immobilization stress-induced hypothalamic somatostatin release in adult male rats. We also observed that glutamate from median eminence-hypothalamic medio basal (ME-MBH) complex, measured by high performance liquid chromatography (HPLC), exhibited a conspicuous secretory pattern, with the total amount released not modified by Dex administration. This indicates that Dex and stress-induced somatostatin (SS) secretion is not mediated by endogenous glutamate variations but likely by activation of NMDA receptors.