Follicle-stimulating hormone-releasing factor (FSH-RF) and luteinizing hormone-releasing factor (LH-RF) in rat hypothalamic extract.

Hypothalamic tissues of female rats were extracted with 1.M acetic acid. The acidic extract was lyophilized and subjected to gel filtration on Sephadex column and assayed for follicle-stimulating hormone-releasing factor (FSH-RF) activity and luteinizing hormone-releasing factor (LH-RF) activity by estimating FSH and LH using the organ culture method of rat anterior pituitaries. FSH activity was measured by the method of Steelman-Pohley, and LH activity by the method of Parlow. Gel filtration on a short column of Sephadex G-25 in 0.1M pyridine acetate provided a single fraction which showed significant FSH-RF and LH-RF activity. Each activity showed a doserelated increase. Application of a long column of Sephadex G-25 in 0.05M pyridine acetate brought about separation of a peak for FSH-RF activity from that for LH-RF activity. The former activity was eluted from the column just before the appearance of the latter. These results indicated that the secretion of FSH and LH from the rat anterior pituitary was regulated by the specific hypothalamic FSH-RF and LH-RF, respectively.