ABSTRACT
C. BARRIGA1 *, J. A. MADRID 2, M. R TERRON], R. V. RIAL3, J. CUBERO ', S. D. PAREDES \ S. SANCHEZl and A. B. RODRIGUEZl 1 Department of Physiology, University of Extremadura, 06071 Badajoz, Spain
Abstract-Research into the activity of the epiphysial complex and its hormone, melatonin, has been part of the growing general interest in chronobiology and in the potential therapeutic applications of melatonin. However, the studies have been almost exclusively oriented to humans and, by extension, to mammals, although humans are diurnal animals, while most other mammals are either nocturnal or crepuscular. The aim of this review is to direct attention to epiphysial complex in birds, diurnal species, that have an immense commercial interest, and the connection between melatonin and the immune system, system responsible for the survival of species. We also go more deeply into biosynthesis, metabolism, regulation and receptors of melatonin, a truly exceptional substance which is perhaps the only biomolecule which has undergone no structural change in all living beings and has probably always been dedicated to biological time measurement and control.
