Thyroid Activity in a Hypometabolic Primate, the Owl Monkey (Aotus trivirgatus)

Abstract

Serum levels of triiodothyronine (T₃) and tetraiodothyronine (T₄) were significantly lower in owl monkeys than in long-tailed macaques. These observations were considered to be consistent with the lower metabolic rate of the owl monkey. However, the absence of a significant difference in the levels of thyroid stimulating hormone (TSH) between the two species suggested a lower thyroid sensitivity to TSH in the owl monkeys. There was an inverse relation between levels of T₃ and TSH in the owl monkeys at night and during the day.