Presence of Thyrotropic Hormone-Releasing Factor (TRF) In Porcine Hypothalamus.

Abstract

Summary Hypothalamic tissue of porcine origin was extracted with 2 N acetic acid at 8°C. The acetic acid extracts were lyophilized and re-extracted with glacial acetic acid. The material thus concentrated was subjected to gel filtration on Sephadex. Thyrotropic hormone-releasing factor (TRF) activity was followed by measuring the release of thyrotropic hormone (TSH) from rat pituitary tissue in vitro, the release of I¹³¹ in mice pretreated with codeine and thyroxine, as well as the elevation of plasma TSH in thyroidectomized rats pretreated with thyroxine. TRF activity was consistently found to emerge between the peaks of α-MSH and lysine vasopressin. Partially purified TRF of porcine origin was active in vitro at the dose of 20 μg and in vivo at the level of 100 μg.