title: Prolonged anti-luteinizing hormone/follicle-stimulating hormone-releasing activities of some synthetic antagonists of luteinizing hormone-releasing hormone.
abstract: A number of synthetic analogs of luteinizing hormone-releasing hormone (LH-RH) were screened for their in vivo antigonadotropin-releasing activities using a four-point bioassay test in immature male rats. Of the peptides tested, the most effective were those containing D-phenylalanine in position 2 of the decapeptide chain in conjunction with D-leucine or, preferably, D-phenylalanine in position 6. Several inhibitory peptides that were found to be very potent were reassayed and compared for duration of inhibition in immature male rats, whereupon the D-Phe2 analogs were found to be particularly long-acting. The most active and persistent peptide of the series, [D-Phe2, D-Phe6]-LH-RH, was able to inhibit the response to exogenous LH-RH for up to 6 hours after its injection.
mesh_terms: D000818:Animals; D001681:Biological Assay; D004353:Drug Evaluation, Preclinical; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors*; D007700:Kinetics; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone