Localization of androgen- and estrogen-concentrating neurons in the diencephalon and telencephalon of the mouse

Adult male mutant mice and their normal littermates (+/y) were castrated (at least 96 h before the experiment) and injected iv with 1 μg/100 g BW either 5α-dihydro-[1, 2, 4, 5, 6, 7(N)^-3H]testosterone (107 Ci/mM) or 17β-[2, 4, 6, 7,^-3H(N)]estradiol (115 Ci/mM) dissolved in 30% ethanol-saline. The animals were killed 2 h later and the brains were removed, sliced, and mounted on tissue holders. The mounted tissues were then frozen in liquified propane and stored in liquid nitrogen until processing. Four-micrometer frozen sections were cut in a cryostat and mounted for autoradiography on emulsion-coated slides, according to the dry mount procedure. The slides were then exposed at –15 C for 2 or 6 months, then photographically processed and stained with methyl green-pyronin. In autoradiograms of the brains of normal male mice injected with [³H]dihydrotestosterone, radioactivity was found concentrated in nuclei of neurons of the following areas: septal-preoptic region, many nuclei within the hypothalamus, thalamus, amygdala., hippocampus, piriform and cingulate cortex. Pretreatment with 100-fold unlabeled testosterone inhibited nuclear localization. In autoradigrams of the brains of mutant mice injected with [³H]dihydrotestosterone, no localization could be found. However, in autoradiograms of brains of mutant male mice injected with [³H]estradiol, radioactivity was found concentrated in nuclei of neurons located predominantly in the limbic system. These studies provide a map of the androgen- and estrogen-concentrating neurons in the diencephalon and most of the telencephalon of the mouse and support the biochemical findings indicating the lack of androgen and the presence of estrogen receptors in the central nervous system of the tfm mutant male mouse.