Melatonin elicits protein kinase C-mediated calcium response in immortalized GT1-7 GnRH neurons.

Haluk Kelestimur, Mete Ozcan, Emine Kacar, Ergul Alcin, Bayram Yılmaz, Ahmet Ayar

Index: Brain Res. 1435 , 24-8, (2012)

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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.Copyright © 2011 Elsevier B.V. All rights reserved.