The effects of melatonin on a molecular level

Abstract

The indole hormone melatonin is secreted in a biphasic circadian rhythm by the pineal gland. This review presents a summary of recent results concerning — (i) factors that influence melatonin synthesis; (ii) the existence of melatonin receptors in brain tissue; (iii) the effects of melatonin as a modulator of dopaminergic, noradrenergic, GABAergic and opioidergic neurotransmitter processes; (iv) the influence of melatonin on the electric activity and metabolic rate of certain brain nuclei; and (v) melatonin effects on hormone secretion in the hypothalamic-pituitary axis. A basic mechanism of melatonin action via cyclic nucleotides and thus protein phosphorylation is presented.