How does the indoleamine production of the pineal gland respond to variations of the environment in a non-mammalian vertebrate, Testudo hermanni Gmelin?

The relative effects of environmental factors, photoperiod and temperature on pineal indoleamine production have been investigated in male Tortoises, Testudo hermanni, at different times of their seasonal reproductive cycle. Photoperiod appears to be an important factor in the regulation of the seasonal and diurnal variations of pineal serotonin content, while temperature has a more drastic effect on the diurnal production of melatonin. These results reinforce, at least partly, the concept that the pineal gland responds to several kinds of information about the state of the environment in order to synchronize some cyclical functions such as reproduction.