Analysis of Foxp2 expression in the cerebellum reveals a possible sex difference.

Deletion of the gene Foxp2 affects ultrasonic vocalizations and induces morphological abnormalities in the Purkinje cell layer of the cerebellum in mice. Castration decreases the production of ultrasonic vocalizations in rats, but the mechanisms of androgenic regulation of ultrasounds are unknown. We explored a possible relationship between Foxp2 expression and androgens in the Purkinje cell layer of wild-type and androgen-insensitive male rats, as well as estrous and nonestrous female rats. Analyses of relative optical densities of Foxp2 immunoreactivity revealed significantly greater immunolabeling in the wild-type and testicular feminization mutation-affected male rats (which did not differ from each other) than in either the estrous or nonestrous female rats (which similarly did not differ from each other). These data suggest a sex difference in Foxp2 expression in the cerebellum.