title: Melatonin elicits protein kinase C-mediated calcium response in immortalized GT1-7 GnRH neurons.
abstract: Melatonin is suggested to have effects on hypothalamic-pituitary-gonadal (HPG) axis. The pulsatile pattern of GnRH release, which results in the intermittent release of gonadotropic hormones from the pituitary, has a critical importance for reproductive function but the factors responsible from this release pattern are not known. Calcium is a second messenger involved in hormone release. Therefore, investigation of the effects of melatonin on intracellular free calcium levels ([Ca(2+)](i)) would provide critical information on hormone release in immortalized GnRH neurons. The pattern of melatonin-induced intracellular calcium signaling was investigated by fluorescence calcium imaging using the immortalized GnRH-secreting GT1-7 hypothalamic neurons. Melatonin caused a significant increase in [Ca(2+)](i,) which was greatly blocked by luzindole, a melatonin antagonist, or attenuated by pre-treatment with protein kinase C inhibitor. This study suggests that melatonin seems to have a direct effect on GnRH neurons.
authors.affiliation: Firat University, Medical School, Department of Physiology, Elazig, Turkey. hkelestimur@firat.edu.tr
authors.forename: Haluk
authors.initials: H
authors.lastname: Kelestimur
authors.forename: Mete
authors.initials: M
authors.lastname: Ozcan
authors.forename: Emine
authors.initials: E
authors.lastname: Kacar
authors.forename: Ergul
authors.initials: E
authors.lastname: Alcin
authors.forename: Bayram
authors.initials: B
authors.lastname: Yılmaz
authors.forename: Ahmet
authors.initials: A
authors.lastname: Ayar
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D053119:Benzophenanthridines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002461:Cell Line, Transformed; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D008550:Melatonin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D014363:Tryptamines / Q000494:pharmacology
chemical_list: D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D014363:Tryptamines; C057154:luzindole; D007987:Gonadotropin-Releasing Hormone; C016299:chelerythrine; D011493:Protein Kinase C; D008550:Melatonin; D002118:Calcium