Nonpregnant guinea pigs have long been known to show male-like sexual behavior when treated with androgens such as testosterone propionate (T.P.). Pregnant females, in contrast, are not so effected (Diamond and Young, 1963). The present report is of the effect of androgens on aggressive behavior in the pregnant and nonpregnant guinea pig and its correlation with male-like sexual behavior.

Two pregnant and two nonpregnant groups of heterogeneous guinea pigs were used. One pregnant and one nonpregnant group was injected with T.P. (5 mg on day 18 of gestation and 1 mg daily thereafter until parturition on day 68). One pregnant and one nonpregnant group remained uninjected. Behavior tests were given at 10 day intervals from day 26 until parturition. Comparable times were used for the nonpregnant females. The test consisted of placing the experimental female into a cage with a non estrous female for 10 minutes and simultaneously recording aggressive and sexual behavior. Attacks, threats and bites were scored as aggression. Male-like mounting was the primary index of sexual behavior.

At the doses and regimen utilized, neither androgens nor pregnancy were found to significantly effect aggressive behavior. Aggression and sex behavior were correlated only for the low activity level of the pregnant group.

The patterns of aggression and sexual behavior seem to be independent in their response to androgen treatment and/or pregnancy.


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