ABSTRACT
We examined the in vitro shuttle metabolism between dihydrotestosterone (DHT) and 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol) by 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD, E.C. 1.1.1.50) in rat submandibular gland (SMG) and ventral prostate (VP). The protein having molecular weight of 30 kDa, which was revealed by Sephacryl S-200 column chromatography, had 3 alpha-HSD activity to produce 3 alpha-diol from DHT, and also showed an oxidative 3 alpha-HSD (3 alpha-HSDO) ability to produce DHT from 3 alpha-diol. From the kinetic studies, the apparent Km and Vmax values of 3 alpha-HSD for DHT and NADPH were 6.4 microM, 1429 pmol/mg protein per min and 33.0 microM, 1205 pmol in SMG, and 9.3 microM, 377 pmol and 34.0 microM, 192 pmol in VP. The corresponding values of 3 alpha-HSDO for 3 alpha-diol and NADP+ were 18.0 microM, 714 pmol and 14.0 microM, 445 pmol in SMG, and 14.0 microM, 417 pmol and 36.0 microM, 77 pmol in VP. The affinities for DHT and 3 alpha-diol and the cosubstrate requirements of this enzyme in SMG were similar to those in VP. However, higher capacities of 3 alpha-HSD and 3 alpha-HSDO in SMG than in VP were shown. This suggests that there may be more 3 alpha-HSD in the SMG.
Subject(s)
3-Hydroxysteroid Dehydrogenases/metabolism , Submandibular Gland/enzymology , Androstane-3,17-diol/metabolism , Animals , Cell Compartmentation , Cell Nucleus/enzymology , Cell Nucleus/metabolism , Cytosol/enzymology , Dihydrotestosterone/metabolism , In Vitro Techniques , Kinetics , Male , Prostate/enzymology , Prostate/metabolism , Rats , Rats, Inbred Strains , Submandibular Gland/metabolismABSTRACT
The constituent cells of the submandibular gland of immature rats were compared with those of adult animals as well as the estrogen and estrogen binding protein level. The submandibular gland of immature and that of adult animals were entirely different in structure. High levels of estrogen binding protein are present in the nuclei in the young male and female submandibular gland. Nuclear estradiol binding protein, however, was not detected in the gland of adults in both sexes. These results suggest that the submandibular gland of the immature rat is influenced by estrogen.
