Secretion of Luteinizing Hormone Releasing Hormone (LHRH) in Monkeys

Abstract

It is established that hypothalamic luteinizing hormone-releasing hormone (LHRH) secretion regulates luteinizing hormone (LH) secretion by the anterior pituitary gland. The classical studies that led to the formulation of the neurovascular hypothesis (1) and eventually to the isolation, characterization, and synthesis of LHRH (2,3) are widely known. More recent studies showing that antiserum to LHRH, administered systemically, blocks LH secretion and ovulation (4) and that LHRH concentrations in pituitary stalk blood are higher than in the peripheral circulation (5,6), leave little doubt that LHRH secretion is essential for LH secretion. However, the quantitative relationship between LHRH secretion and LH secretion remains unknown. For instance, it is not established whether increases in LHRH secretion accompany increases in LH secretion during the preovulatory surge or after ovariectomy. Numerous investigators (7–10) have attempted to correlate LHRH concentrations in peripheral plasma, using bioassays and radioimmunoassays, with LH levels; however, the identity of the substance measured remains in doubt. Although more convincing measurements of LHRH have been made in pituitary stalk blood of the rat (5,6), correlations of LHRH and LH could not be made during a spontaneous LH surge because the anesthetic required for stalk blood collection blocked LH secretion. Finally, the demonstration that estrogens have profound effects on the response of the pituitary to LHRH (11–14) has raised the possibility that changes in LHRH secretion might have only a minor part in determining the level of LH secretion.KeywordsLuteinizing HormoneCavernous SinusLUTEINIZING Hormone Release HormoneLuteinizing Hormone LevelLuteinizing Hormone SurgeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.