Purification of Thyrotropic Hormone-Releasing Factor from Bovine Hypothalamus

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Abstract
Acetic acid extracts of hypothalamic tissue of bovine origin were concentrated by a precipitation procedure and 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 from Sephadex just after [alpha]-MSH (melanocyte-stimulating hormone) and before arginine vasopressin. The TRF zone from Sephadex was further greatly purified by phenol extraction and then subjected to chromatography on carboxymethylcellulose (CMC). TRF area from CMC was repurified by rechromatography. Purified TRF was active in vivo at the level of 10 [mu]g and in vitro at the dose of 1 [mu]g. Chemical and biological characteristics indicate the TRF is a weakly basic poly-peptide different from oxytocin, vasopressin, [alpha]- and [beta]-MSH and LRF.