FEMININE DIMENSION IN THE PLAY FIGHTING OF RATS (RATTUS-NORVEGICUS) AND ITS DEFEMINIZATION NEONATALLY BY ANDROGENS

In rats (Rattus norvegicus), juvenile males engage in more play fighti ng (a male-typical behavior) than do juvenile females, and this differ ence is based on perinatal influences of androgens. We show that there are qualitative and quantitative differences between the sexes in the type of defensive responses and their manner of execution. In defensi ve responses rats try to avoid having their napes contacted by the par tner's snout. The sex differences arise from females' greater response distance; that is, females responded to an approach when the partner' s snout was further from the nape. This permits females to use differe nt defensive responses and to use them more successfully. This greater response distance is defeminized by the neonatal administration of te stosterone propionate. Our findings suggest that play fighting in rats has both male- and female-typical features and that these are, at lea st in part, influenced perinatally by androgens.