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Novel G‐Protein Coupled Receptor Ligands and Neurohypophysial Hormones
Author(s) -
Ueta Y.,
Ozaki Y.,
Saito J.
Publication year - 2004
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 - 10.1111/j.0953-8194.2004.01179.x
Subject(s) - galanin , medicine , endocrinology , oxytocin , posterior pituitary , vasopressin , neuropeptide , magnocellular cell , anterior pituitary , hypothalamus , receptor , supraoptic nucleus , galanin receptor , chemistry , biology , pituitary gland , hormone
Recently, novel peptides have been identified as unknown ligands of orphan G‐protein coupled receptors. In the paraventicular (PVN) and supraoptic nuclei (SON), the expression of the G‐protein genes are abundant. In this review, we focus on the physiological role of neuromedin U and galanin‐like peptide, which were recently identified as ligands of G‐protein coupled receptors, in the regulation of neurohypophysial hormones. Intracerebroventricular (i.c.v) administration of neuromedin U induced the expression of c‐ fos mRNA in both the magnocellular and parvocellular division of the PVN and throughout the SON. Administration of i.c.v. neuromedin U caused a significant increase in plasma concentrations of vasopressin and oxytocin as well as adrenocorticotropic hormone. The expression of galanin‐like peptide mRNA was observed in the pituicytes of rat posterior pituitary gland. The expression of galanin‐like peptide mRNA in the posterior pituitary gland was markedly increased after dehydration, salt loading and intraperitoneal administration of lipopolysaccaride, challenges that stimulate the secretion of vasopressin and oxytocin, and which activate the hypothalamic‐pituitary adrenal axis. These results suggest that neuromedin U and galanin‐like peptide may have an important role in the regulation of both the hypothalamic‐neurohypophysial system and the hypothalamic‐adrenohypophysial system.