Behavioral interactions of postweaning male and female rats with a complex environment

Rats reared from weaning in a complex environment with other rats and numerous objects display sex differences in several brain areas, yet there is little systematic information on the types of interactions that rats have within complex environments or whether there are sex differences in these interactions. Therefore, male and female rats were observed in the complex environment over a 15-30 day period in three separate replications that included same-sex and mixed sex groups of rats. The rats spent considerably more time interacting with the objects than in social interactions in all replications, and the types of interactions varied little over the length of the study. A few sex differences appeared, such as in play fighting, but these differences were small and not consistent across replications. Male and female rats interacted with the environment in a very similar manner.