title: Role of ionotropic glutamate receptors in the control of prolactin secretion by other neurotransmitters and neuropeptides at the level of the pituitary.
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.
authors: Department of Zoology, Dr H.S. Gour University, India.
authors: S K
authors: SK
authors: Jain
authors: D
authors: D
authors: Zelena
mesh_terms: D000818:Animals; D001569:Benzodiazepines / Q000494:pharmacology; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism; D008297:Male; D009479:Neuropeptides / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D058468:Receptors, Ionotropic Glutamate / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism
chemical_list: D018691:Excitatory Amino Acid Antagonists; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D058468:Receptors, Ionotropic Glutamate; C061950:GYKI 52466; D001569:Benzodiazepines; D012701:Serotonin; D014660:Vasoactive Intestinal Peptide; D018698:Glutamic Acid; D013973:Thyrotropin-Releasing Hormone; D016291:Dizocilpine Maleate; D011388:Prolactin; D004298:Dopamine