Stimulation of Release of Follicle-Stimulating Hormone by Hypothalamic Extractsin Vitroandin Vivo

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Abstract
Acetic acid extracts of beef and sheep stalk-median eminence tissue were tested for their effects on release of FSH in vitro and in vivo. The Steelman-Pohley rat ovarian weight and the Igarashi-McCann mouse uterine weight methods were used to detect FSH activity. In vitro experiments consisted of incubation of isolated anterior pituitary tissue from estrogen progesterone treated spayed (EPS) rats. Addition of hypothalamic extracts to the incubation medium raised its FSH activity. In vivo tests consisted of measurement of plasma FSH activity in EPS rats. Injection of the extracts significantly raised plasma FSH activity. The effects of extracts were not due to contamination with FSH or substances having FSH-like activity or to potentiation of endogenous FSH by the extracts. Extracts of brain cortex and lysine vasopressin did not evoke measurable release of FSH either in vitro or in vivo. The results indicate that beef and sheep hypothalamic extracts contain a factor or factors which, both in vivo and in vitro, can stimulate FSH release from the anterior pituitary of the rat. (Endocrinology76: 614, 1965)