Endocrine Abstracts

Fasting produces a rapid reduction of the activity of the central arm of the hypothalamic–pituitary–thyroid (HPT) axis, with a drop in biosynthesis of thyrotropin releasing hormone (TRH) in periventricular and medial parvocellular neurons of the paraventricular nucleus (PVN), and decreased TRH release into the pituitary portal capillaries. These events contribute to fasting-induced suppression of serum thyroid hormone levels, an adaptive mechanism to conserve energy....

The activity of hypothalamus–pituitary–thyroid (HPT) axis is essential for energy homeostasis. TRH expression in the PVN is rapidy stimulated by energy demanding situations as cold exposure or locomotion, but blunted by stress-induced increased corticosterone serum levels. In primary cultures of rat hypothalamic cells (RHC), PKA activators as forskolin (Fsk) increase TRH mRNA levels, effect reverted by coincubation with dexamethasone. Fsk-dex coincubation also impede...