Genomics Inform.  2007 Jun;5(2):77-82.

Serotonin (5-HT) Receptor Subtypes Mediate Regulation of Neuromodulin Secretion in Rat Hypothalamic Neurons

• Chin C
• Kim SI

Abstract

Serotonin (5-HT), the endogenous nonselective 5-HT receptor agonist, activates the inositol -1,4,5- triphosphate / calcium (InsP3/Ca2+) signaling pathway and exerts both stimulatory and inhibitory actions on cAMP production and neuromodulin secretion in rat hypothalamic neurons. Specific mRNA transcripts for 5-HT1A, 5-HT2C and 5-HT4 were identified in rat hypothalamic neurons. These experiments were supported by combined techniques such as cAMP and a Ca2+ assays in order to elucidate the associated receptors and signaling pathways. The cAMP production and neuromodulin release were profoundly inhibited during the activation of the Gi-coupled 5-HT1A receptor. Treatment with a selective agonist to activate the Gq-coupled 5-HT2C receptor stimulated InsP3 production and caused Ca2+ release from the sarcoplasmic reticulum. Selective activation of the Gs-coupled 5-HT4 receptor also stimulated cAMP production, and caused an increase in neuromodulin secretion. These findings demonstrate the ability of 5-HT receptor subtypes expressed in neurons to induce neuromodulin production. This leads to the activation of single or multiple G-proteins which regulate the InsP3/Ca2+/PLC-gamma and adenyl cyclase / cAMP signaling pathways.

Keyword

neuromodulin signaling; selective serotonin agonists; rat hypothalamus; cAMP; intracellular Ca2+

MeSH Terms

Animals
Calcium
GAP-43 Protein*
GTP-Binding Proteins
Inositol
Neurons*
Rats*
Receptor, Serotonin, 5-HT1A
Receptor, Serotonin, 5-HT2C
Receptors, Serotonin, 5-HT4
RNA, Messenger
Sarcoplasmic Reticulum
Serotonin*
Adenylyl Cyclases
Calcium
GAP-43 Protein
GTP-Binding Proteins
Inositol
RNA, Messenger
Receptor, Serotonin, 5-HT1A
Receptor, Serotonin, 5-HT2C
Receptors, Serotonin, 5-HT4
Serotonin