Ambiente e sistema endocrino: la sincronizzazione dei ritmi endogeni nei vertebrati

Vertebrate physiology and behaviour follow circadian and circannual rhythms, which result in adapting to the cyclical variations of the environment, such as photoperiod and temperature. To interpret the light/dark cycle, the first vertebrates (fish and larval amphibians) use the “third eye”, a photoreceptor organ of the epithalamus, which during evolution turned into an endocrine gland, named epiphysis or pineal gland. This gland produces melatonin, a hormone that still carries the photoperiod-linked message. This article discusses some evolutionary aspects of the epithalamic structures and multiple functions of melatonin.