Neural uptake and metabolism of testosterone and dihydrotestosterone in the guinea pig.
Neural tissues from adult, castrated male guinea pigs were examined for their capability to concentrate and metabolize [1,2-3H]testosterone (T) and [1,2-3H]dihydrotestosterone (DHT), both in vitro and in vivo. In vitro uptake of DHT and T was greater in the hypothalamus and anterior pituitary than in the cerebral cortex. With DHT as the substrate, the 800 times g particulate concentration of this compound was highest in the hypothalamus, although in this tissue, particulate concentration was less than that of the cytoplasm. In the cerebral cortex 5alpha-androstane-3,17-dione was the most abundant metabolite, whereas 5alpha-androstane-3,17-dione, 5alpha-androstane-3alpha,17beta-diol, and 5alpha-androstane-3beta,17beta-diol were all present in equivalent amounts in the hypothalamus and pituitary. Incubation with T resulted in the formation of DHT, 4-androstene-3,17-dione, and a compound with the mobility of 5alpha-(or 5beta-)androstane-3,17-dione. The radioactivity associated with DHT was the most prevalent in the pituitary (1.3%), and least prevalent in the cerebral cortex (0.6%), and in all cases cytoplasmic concentration of this compound exceeded the concentration in the particulate fraction. Recrystallization failed to confirm the presence of estradiol-17beta. Although there were no apparent tissue differences in the uptake of DHT or T 1 hour after their injection, intracellular distribution varied. In all tissues examined, that percentage of total radioactivity attributable to DHT was greatest in the 800 times g particulate preparations, particularly in the hypothalamus. Thus neural tissues in the guinea pig, as in other species, exhibit differential uptake and metabolism of androgen through which physiological and behavioral effects may be mediated.
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D013196:Dihydrotestosterone / Q000378:metabolism*; D006168:Guinea Pigs; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D009928:Organ Specificity; D010902:Pituitary Gland / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism*
D013196:Dihydrotestosterone; D013739:Testosterone