Separation of Follicle-Stimulating Hormone-Releasing Factor from Luteinizing Hormone-Releasing Factor

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Abstract
Sheep stalk-median eminence extract was subjected to gel filtration on a long (150×4.5 cm) column of Sephadex G-25 in 0.1M ammonium acetate. FSH-releasing activity was evaluated by the change in plasma FSH activity induced by intravenous injection of fractions into ovariectomized, estrogen progesterone-blocked rats. LH release was determined by ovarian ascorbic acid depletion produced in immature test rats pretreated with gonadotrophins. A sharp peak of FSHreleasing activity was found in fractions which were eluted from the column before the LHreleasing and pressor zones. Although the LHreleasing area overlapped the descending limb of the FSH-releasing curve, the 2 peaks were distinctly separated. A dose response relationship was demonstrated for both FSH and LH release with certain active fractions. It was concluded that sheep hypothalamic extract contains discrete FSH- and LH-releasing factors. (Endocrinology76: 290, 1965)