Peptide hormones. 95. Inhibition of the activity of the luteinizing hormone-releasing hormone (LH-RH) by analogs with variations at positions 2, 3, and 6 and the carboxyl terminus

Abstract

In isolated rat pituitary assay, [Thr2,Leu3]-LH-RH, [Leu2,Ala3,D-Ala6]-LH-RH, and des-Gly10-[Abu2,Ala3,D-Ala6]-LH-RH ethylamide inhibited LH release due to 0.3 ng/ml of added LH-RH at a 10 .mu.g/ml dosage. Under these same assay conditions, des-Gly10-[Ile2,Ala3,D-Ala6]-LH-RH ethylamide was about 1/10 as active, and no inhibition was observed by [Leu2,Ser3]-LH-RH or [Leu2,Asn3]-LH-RH at a 100 .mu.g/ml dosage. The corresponding results from FSH [follicle stimulating hormone] inhibition assays in vitro are reported.