COPULATORY ACTIVITY IN ADULT MALE RATS FOLLOWING CASTRATION AND INJECTIONS OF TESTOSTERONE PROPIONATE1

THIS STUDY is concerned with the loss of sexual aggressiveness in adult male rats following castration and the restoration of sexual activity by subcutaneous injections of testosterone propionate. Steinach (1) in 1894 observed that the male rat may copulate as late as 1 year following total castration (1 case). Since that time, many investigators have verified the fact of copulatory ability in man and the lower vertebrates following castration (2). In 1927 Stone (3) studied the copulatory activity of 45 male rats that had been castrated at the age of 90 days. These males were given short tests for copulatory activity at intervals of from 4 to 6 days until they were sexually inactive for a period of approximately 30 days. Considering the group as a whole, 33 per cent had ceased to copulate before the end of the first month following castration; 45 per cent, before the end of the second month; 57 per cent, the third; 74 per cent, the fourth; 79 per cent, the fifth; and 91 per cent, the sixth.