Abstract
GABA plays an essential role in the regulation of GnRH neurons and melatonin is involved in reproductive functions. Besides, melatonin is recently reported to modulate the current through GABAA receptor (GABAA current) in certain central neurons. We, therefore, decided to examine the effect of melatonin on GABAA current in rat GnRH neurons. Transgenic rats with EGFP tagged to GnRH neurons were used. After enzymatic digestion, EGFP-GnRH neurons were cultured overnight with Neurobasal-A medium supplemented with L-glutamine and B-27. The currents were recorded with perforated patch clamp configuration. GABA (30 μM) was applied by puff and melatonin (10-1000 nM) was applied through perfusion. Melatonin reduced the GABAA current in adult females while augmented the current in adult males. These effects of melatonin were blocked either by melatonin receptor antagonist luzindole (1 μM) or by pretreatment with pertussis toxin (100 ng/ml). There was no apparent effect of melatonin on GABAA current in infantile GnRH neurons in both sexes. In conclusion, GABAA current in rat GnRH neurons was modulated by melatonin via melatonin receptor. The modulation was developmentally and sexually regulated. [Jpn J Physiol 55 Suppl:S141 (2005)]
