Melatonin Binding Sites in Endocrine and Immune Systems

Melatonin has been considered to be exclusively a photoperiodic signal by most scientists. This special issue reviews published results and presents new findings strongly supporting the hypothesis of direct melatonin actions on endocrine and immune systems. There is detailed information on melatonin interaction in the pars tuberalis in seasonal and non-seasonal breeders, on target sites in the pituitary, adrenal glands, gonads, Harderian gland and mammary tissues. Evidence is presented for the primary and secondary lymphoid tissues to be targets of melatonin. These findings focus on actions of melatonin on immune and endocrine systems which are not mediated by the CNS. The potential importance of these mechanisms for pharmacologic intervention and in pathophysiology is evident and should be of interest to research endocrinologists, immunologists and pharmacologists.