scope:

Synthesis and release of pineal melatonin are increased at night with a season-dependentcharacteristic pattern. The seasonal alterations in melatonin production constitute a keyendocrine message used to time annual functions with seasons. Although the nervous pathway and cellular/molecular mechanisms involved in the daily regulation of melatonin production have been intensively investigated, those responsible for the seasonal variations in melatonin synthesis and release have just started to be studied. This review aims at defining how the melatonin pattern transduces seasonal information in various rodent species, and what could be the nervous and endocrine inputs, as well as the cellular and molecular elements underlying the seasonal alterations of the melatonin pattern.