Contraceptive treatment of male mammals

Abstract

Peptides which are LRF analogs that inhibit the secretion of gonadotropins by the pituitary gland and inhibit the release of steroids by the gonads can be effective contraceptives when administered to male mammals. The peptides are LRF antagonists having a binding affinity at least about 15 times that exhibited by LRF and having an ICR.sub.50 of less than 1/l. Examples of peptides which may be used are those having the structure: R.sub.1 --R.sub.2 --R.sub.3 --D--Trp--Ser--Tyr--R.sub.4 --Leu--Arg--Pro--Gly--NH.sub.2 wherein R.sub.1 is selected from the group consisting of hydrogen, formyl, acetyl, acrylyl, benzoyl and allyl; R.sub.2 is selected from the group consisting of dehydro Pro, dehydro D--Pro, Thz and D--Thz; R.sub.3 is selected from the group consisting of pCl--D--Phe, pF--D--Phe, pNO.sub.2 --D--Phe and 3,4 Cl--D--Phe; R.sub.4 is selected from the group consisting of D--Trp and (imBzl) D--His; and Leu may be substituted by N MeLeu. Effective contraception is achieved at a daily dosage level of not more than about 3 mg. per Kg. of body weight.

Dependencies are inferred from the claim text.