Effects of a luteinizing hormone-releasing hormone antagonist in late-juvenile female rats: blockade of follicle growth and delay of first ovulation following suppression of gonadotropin concentrations.
Subcutaneous injections of an antagonist against luteinizing hormone-releasing hormone (LHRH-A, Org, 30276) were administered to late-juvenile female rats. The effects on timing of vaginal opening and first ovulation on serum gonadotropin concentrations and on follicle growth were studied. The dose of 100 micrograms LHRH-A/100 g body wt, given on Days 28, 31, and 34, did not influence timing of first ovulation. After administration of 500 micrograms LHRH-A/100 g body wt, ovulation was retarded by 4.7 days if injections were given on Days 28 and 31; by 6.7 days if given on Days 28, 31, and 34; and by 11.5 days if given on Days 28, 31, 34, and 37. Serum LH and FSH concentrations 3 days after the first, second, and third injections of 500 micrograms LHRH-A were significantly (p less than 0.01) lower than in saline-treated controls. Ovarian follicle counts showed decreased numbers of (antral) Class 2, 3, and 4 follicles 3 days after injection of 500 micrograms LHRH-A/100 g body wt on Day 28; a significantly higher number of Class 1 follicles and a further decrease in Class 2, 3, and 4 follicles 3 days after the second LHRH-A injection; and total absence of Class 3, 4, and 5 follicles 3 days after the third LHRH-A injection. Six days after the third LHRH-A injection, Class 3 and 4 follicles reappeared in the ovaries.(ABSTRACT TRUNCATED AT 250 WORDS)
Meijs-Roelofs
H M
HM
Department of Anatomy, Medical Faculty, Erasmus University, Rotterdam, The Netherlands.
Kramer
P
P
Van Cappellen
W A
WA
Van Leeuwen
E C
EC
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D007279:Injections, Subcutaneous; D007986:Luteinizing Hormone / Q000097:blood; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D010060:Ovulation / Q000187:drug effects* / Q000502:physiology; D011359:Proestrus / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D007987:Gonadotropin-Releasing Hormone; C042691:LHRH, N-acetyl-(4-chlorophenylalanyl)(1)-(4-chlorophenylalanyl)(2)-tryptophyl(3)-arginyl(6)-alanine(10)-; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone