Current status of luteinizing hormone-releasing hormone in diagnosis and treatment of disorders in reproductive function.

The concept of the hypothalamic regulation of the function of the anterior pituitary was established by experiments involving the interruption of blood supply from the hypothalamus to the pituitary, transplantation of pituitary to sites away frm the hypothalamus and the effects of various lesion and electrical stimulation experiments with the hypothalamus. These experiments were the result of the concept proposed by Harris in 1937 that the pituitary gland may be controlled by the brain through substances carried to it by the portal vessels arising in the hypothalamus. The first direct evidence of the presence of a hypothalamic factor that could bring about the release of pituitary LH was provided independently in 1960 by McCann and co-workers and in 1961 by Harris and co-workers. The releasing factors and their physiological role was a subject of great interest, and porcine LH-RH was isolated by Schally et al. in 1971, followed by the isolation of ovine LH-RH by Guilleman and co-workers. The structure of the releasing factor has been established with no species differences between the ovine and porcine preparation and the decapeptide which has been synthesized. The use of LH-RH on various experimental animals has been done extensively, and evidence of the release of both LH and FSH has been obtained. In the absence of concrete evidence for a separate FSH-RH at this time, the above observation has led to the speculation that there is a single releasing factor that brings about the release of both FSH and LH. Both natural hormone from either ovine or porcine origin and the synthetic decapeptide have biological activity in the human. However, the rhesus monkey seems to be much less sensitive, and the question of a species difference has been raised. This subject has been reviewed in considerable detail by Schally and co-workers.