Effect of the LRF-antagonist [D-pGlu1, D-Phe2, D-Trp3,6]-LRF on pregnancy in the rat

The potent LRF-antagonist [D-pGlu1, D-Phe2, D-Trp3,6]-LRF (Antag.) has been examined for its effect in mated female rats. While 1.25 mg Antag. given b.i.d. for 7 days after mating prolongs pregnancy, the administration of 2.5 mg Antag. b.i.d. for the same period results in the complete absence of developing fetuses.