10-Nor-Progesterone, a Physiologically Active Lower Homolog of Progesterone

The activity of 10-norprogesterone a physiologically active lower homolog of progesterone was tested in 2 castrated sexually mature rabbits. The rabbits were castrated 18 hours after mating. 1 rabbit received a total of 4.1 mg over a period of 5 days and at autopsy 6 normal blastocysts were found in the uterus with full proliferation in the endometrium. The 2nd rabbit received a total of .83 mg with no blastocysts observed in the uterus but with complete endometrial proliferation. This compound appears to be at least as active as progesterone and these results indicate that the angular methyl group at C-10 can be replaced with hydrogen without impairing the physiological activity.