Releasing Factors in Human Hypothalamic and Neurohypophysial Extracts

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Abstract
Human hypothalamic tissues were defatted with acetone, extracted with 2N acetic acid, subjected to prolonged boiling and lyophilized. Acetone defatted human neurohypophysial tissues which included the pituitary stalk were extracted with acetic acid and lyophilized. The polypeptide materials in such extracts were concentrated by glacial acetic acid extraction, gel filtration on Sephadex and phenol extraction. Multiple assays were performed with these human hypothalamic extracts and purified human neurohypophysial preparations in order to determine their content of hypothalamic releasing factors. Luteinizing hormone-releasing factor (LRF) activity was determined by injection of test material into ovariectomized rats pretreated with estrogen and progesterone. The plasma of those animals was assayed for LH by the ovarian ascorbic acid depletion method. Thyrotropin-releasing factor (TRF) activity was estimated by measuring the release of 131I from the thyroids of mice pretreated with codeine and 1/μg thyroxine and by stimulation of TSH release in vitro. Growth hormone-releasing factor (GRF) activity and follicle-stimulating hormone-releasing factor (FSH-RF) activity were measured by depletion of pituitary content of GH and FSH, respectively, in rats. Corticotropin releasing factor (CRF) was measured by elevation of plasma ACTH in rats treated with chlorpromazine, morphine and Nembutal. Both human hypothalamic and human neurohypophysial materials showed considerable LRF, FSH-RF, GRF, TRF, CRF and ACTH-like activities. The results indicate that human hypothalamic extracts, in analogy to those of domestic and laboratory animals, contain factors which mediate the release of pituitary hormones.