Is testosterone metabolized to estrogen in the forebrain of the Rockland-Swiss mouse?

The nuclear uptake and retention of [³H]testosterone or one of its metabolites was examined in the Rockland-Swiss (R-S) mouse. Castrated male and female mice were injected with 0.2 μg of testosterone [1,2,6,7-³H(N)] per 100 g body weight and killed 1.5 h later. The brains were removed and processed for autoradiography. A nuclear localization of [³H]testosterone or one of its metabolites was found in the nucleus (n.) interstitialis striae terminalis and the n. amygdaloideus medialis. This localization is very different from that reported in another strain of mouse after the injection of [³H]dihydrotestosterone. Together with previous reports, these data suggest: (1) that aromatization of T to E₂ in the forebrain of the R-S mouse is of minimal consequence; (2) there may be differences in uptake of T or its metabolites in different strains of mice; and (3) different androgens may exhibit unique patterns of nuclear uptake and retention.