Some Effects of the Hypothalamic Luteinizing Hormone Releasing Factor on the Biosynthesis and Release of Luteinizing Hormone

The biosynthesis and release of luteinizing hormone (LH) have been demonstrated in the rat pituitary gland incubated in vitro, the LH being measured by means of an immunological assay. After castration, the synthesis and release of LH are increased. Hypothalamic extract significantly stimulates the release of LH, but, at the same or higher concentrations, has no effect on the incorporation ofeither 14C-leucine or 14C-glucosamine into LH. Three days after injecting estrogen plus progesterone into ovariectomized rats no effect on rate of incorporation of leucine into LH is observed, although LH release, as stimulated by hypothalamic extract, is enhanced. It is postulated that the main effect of the hypothalamic luteinizing hormone releasing factor (LRF) is on LH release. (Endocrinology81: 835, 1967)