Effects of warm and cold temperatures on release of TSH, GH, and prolactin in rats.

Abstract

SummaryWhen mature male rats were placed in a chamber at 40° for 30 or 60 min, there were significant decreases in serum TSH and plasma GH, and a five- to tenfold elevation of serum PRL. A temperature of 4° for 1 or 2 hr increased serum TSH, did not significantly alter plasma GH levels, and resulted in a significant fall in serum PRL. The observation that TSH and PRL responded oppositely to the same temperature changes suggests that different mechanisms regulate release of these two hormones under these conditions. The possible role of stress, and the interactions of the hypothalamic hypophysiotropic hormones and biogenic amines in the temperature-induced changes remain to be evaluated.Note in proof: Wettemann and Tucker (Proc. Soc. Exp. Biol. Med. 146, 908 (1974)) recently reported that cattle exposed to increased ambient temperature showed a significant rise in blood prolactin levels, whereas exposure to cold ambient temperature resulted in a significant fall in blood prolactin. Thus cattle and rats sho...