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....