Melatonin inhibits voltage-gated potassium K4.2 channels and negatively regulates melatonin secretion in rat pineal glands.

Melatonin is synthesized in and secreted from the pineal glands and regulates circadian rhythms. Although melatonin has been reported to modulate the activity of ion channels in several tissues, its effects on pineal ion channels remain unclear. In the present study, the effects of melatonin on voltage-gated K (K) channels, which play a role in regulating the resting membrane potential, were examined in rat pinealocytes.