Effects of luteinizing hormone releasing hormone on gonadotrophins in the hamster.
The changes in serum gonadotrophins in male hamsters following one injection of 15 micrograms luteinizing hormone releasing hormone (LHRH) (Group A) were compared with those following the last injection of LHRH in animals receiving an injection approximately every 12 hr for 4 days (Group B) or 12 days (Group C). Peak follicle stimulating hormone (FSH) levels (ng/ml) were 1776 +/- 218 (Group A), 2904 +/- 346 (Group B), and 4336 +/- 449 (Group C). Peak luteinizing hormone (LH) values (ng/ml) were 1352 +/- 80 (Group A), 410 +/- 12 (Group B), and 498 +/- 53 (Group C). Serum FSH:LH ratios, calculated from the concentrations measured 16 hr after the last LHRH injections, were higher in Groups B and C than in Group A. Similar injections of LHRH (100 ng or 15 micrograms/injection) for 6 days elevated the serum FSH:LH ratio in intact males. Five such LHRH injections (100 ng/injection) blunted the rise in serum LH in orchidectomized hamsters. Direct effects of LHRH on gonadotrophin secretory dynamics or altered brain-pituitary-testicular interactions may alter the ratio of FSH to LH in the hamster.
D000818:Animals; D002369:Castration; D006224:Cricetinae; D005640:Follicle Stimulating Hormone / Q000097:blood* / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007700:Kinetics; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011863:Radioimmunoassay; D013997:Time Factors
D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone