Abstract
Anterior pituitary glands from normal female rats were cultivated by the organ culture method in an attempt to investigate whether extract of the rat hypothalamus may stimulate the glands directly to release FSH, LH or both. Hypothalamic tissues of mature female rats were extracted with 1.0M acetic acid. FSH-RF or LHRF activity of the extract was determined by estimating FSH or LH activity of cultures treated with the extract. FSH activity was measured by the method of Steelman-Pohley, and LH activity was done by the method of Parlow. The extract could stimulate the release of signifocant amounts of LH, whereas brain cortical extract, oxytocin and lysine-vasopressin were inactive. Contamination of LH in the extract was denied. The results provide evidence for the presence of an LH-RF in the rat hypothalamus. On the other hand, whether there is an FSH-RF in the rat hypothalamus needs to be further investigated. Autoradiography of cultivated glands demonstrated that the hypothalamic extract increased the uptake of 3H-leucine by PAS-positive cells, indicating that the action of the extract is probably related to the synthesis of gonadotropin.
