Role of ionotropic glutamate receptors in the control of prolactin secretion by other neurotransmitters and neuropeptides at the level of the pituitary.

Jain, S. K. and Zelena, Dóra (2013) Role of ionotropic glutamate receptors in the control of prolactin secretion by other neurotransmitters and neuropeptides at the level of the pituitary. ENDOCRINE REGULATIONS, 47 (2). pp. 65-74. ISSN 1210-0668

Text 2013EndReg_Jain_PRL_in_vitro.pdf Restricted to Registered users only Download (316kB) | Request a copy

Abstract

OBJECTIVE: Although prolactin (PRL) plays an important role in the milk production, it has also many other functions. PRL secretion can be inhibited by dopamine and stimulated by serotonin, thyrotropin releasing hormone (TRH), and vasoactive intestinal peptide (VIP). However, the exact mechanisms of PRL regulation are still not fully understood. Glutamate is also a potent elevator of PRL secretion. It has several receptors: ionotropic NMDA (N-methyl-D-aspartate) and non-NMDA as well as metabotropic receptors. Our interest was to find out whether endogenous glutamate may act at the hypophyseal level and affect the PRL regulating neurotransmitters (dopamine, serotonin, TRH, VIP). METHODS: MK-801 as NMDA blocker and GYKI52466 as a non-NMDA antagonist were used in this study. For dopamine and serotonin experiments intraperitoneal drug administration and blood sampling were applied. On the other hand, TRH and VIP effect on PRL secretion was studied in in vitro conditions by incubating them with a half 300*300nm choppered anterior pituitary gland of the adult male rats. RESULTS: The basal PRL levels were not influenced by the glutamate antagonists used either alone or combined in both in vivo and in vitro conditions. We failed to reveal interaction between dopamine-, serotonin-, and TRH-induced PRL rise and antagonists treatment. MK-801 had a significant inhibitory effect on VIP-induced PRL changes. CONCLUSIONS: Our data confirmed the regulatory role of dopamine, serotonin, and TRH on PRL secretion, however, the interaction between these and glutamatergic systems was not confirmed, at least not via the ionotropic receptors. On the other hand, the endogenous glutamate can through the NMDA receptor subtype contribute to the VIP-induced PRL secretion at the level of the anterior pituitary. This regulation may be especially important during suckling and stress response when rapid release of PRL is required.

Actions (login required)

Edit Item