Differential control of luteinizing hormone and follicle-stimulating hormone by luteinizing hormone releasing hormone in the ram.
Adult Soay rams with low concentrations of gonadotrophins in the circulation as a result of 12 weeks of exposure to long daylengths (16 h light : 8 h darkness) were given small doses (100 ng) of synthetic luteinizing hormone releasing hormone (LH-RH) into the jugular vein two, four or seven times/day for 10 days. Each injection of LH-RH induced a transitory increase in the concentration of LH and testosterone in the plasma, whereas the concentration of FSH showed little immediate change. After repeated treatment with pulses of LH-RH, the responses of LH and testosterone became slightly enhanced and the plasma concentration of FSH became permanently raised; these changes were most conspicuous in the animals receiving the most frequent injections. At the end of the study when the injections of LH-RH were stopped, the concentrations of LH and testosterone remained low but the concentrations of FSH continued to be maintained at a high level for at least 24 h.
D000818:Animals; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology / Q000502:physiology*; D008027:Light; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D008297:Male; D012636:Secretory Rate / Q000187:drug effects; D012756:Sheep / Q000502:physiology*; D013739:Testosterone / Q000097:blood / Q000378:metabolism; D013997:Time Factors
D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone