Manuel Puig-Domingo

TL;DR: The data demonstrate the existence of a 24-h rhythm of type II T4 5'-D activity in pineal gland and cortex, with peak levels occurring at night; in Pineal, the sympathetic neural input is indispensable for the rhythm, since SCGX prevented it, and in cortex, the apparent paradoxical effect of LL and SCG X on 5'D activity indicates that other mechanisms are involved in its regulation.

TL;DR: Intact male hamsters had very low levels of Harderian HIOMT activity and melatonin content in comparison with the glands of the females, and testosterone implants in the castrated males led to a recovery of the original male NAT levels.

TL;DR: The presence of type‐II thyroxine 5′‐deiodinase (5′‐D) activity in rat pineal gland and N‐acetyltransferase (NAT) activity, and melatonin content were measured in the same rat Pineal.

TL;DR: It is suggested that interruption of the synthesis of proteins is responsible for the slow deterioration of 5′-D activity induced by either light or propranolol.

TL;DR: Castrated hamsters exposed to long days showed higher NAT activity than that of castrated animals exposed to short photoperiods indicating that light may have some influence on Harderian NAT independent of the gonadal status, and HIOMT activity and melatonin content in all these groups of male Syrian hamsters were very low.