title: Synergistic effects of estrogen with androgen on the prostate--effects of estrogen on the prostate of androgen-administered rats and 5-alpha-reductase activity.
abstract: To clarify the effects of estrogen on the prostate of androgen-treated rats, we administered estradiol (E2; 0.01 mg/day) to testosterone (T; 1 mg/day)-treated Wistar rats under various conditions. There were three variable factors: the age of the rat, the untreated period after castration, and the presence of testes. Under all conditions, E2 stimulated the growth of the prostate in T-treated rats compared with growth in rats in treated with T only. To analyze the mechanism underlying this enhancement of prostate growth by estrogen, we measured 5-alpha-reductase activity and calculated its kinetic parameters, i.e., both Vmax and Km. The Vmax of the nuclear fraction was higher in E2-administered T-treated rats than in T only-treated rats. In contrast, the Vmax of the microsomal fraction was lower in E2-administered rats. Km values in the two groups showed no significant differences. Elevation of the nuclear fraction of 5-alpha-reductase activity could explain the synergistic effects of estrogen on the prostate growth of androgen-treated rats.
authors.affiliation: Department of Urology, Gunma University School of Medicine, Maebashi, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Suzuki
authors.forename: Y
authors.initials: Y
authors.lastname: Takezawa
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: S
authors.initials: S
authors.lastname: Honma
authors.forename: H
authors.initials: H
authors.lastname: Yamanaka
mesh_terms: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000378:metabolism*; D000375:Aging / Q000378:metabolism; D000818:Animals; D004357:Drug Synergism; D004958:Estradiol / Q000494:pharmacology*; D008297:Male; D009919:Orchiectomy; D011467:Prostate / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D051381:Rats; D017208:Rats, Wistar; D013737:Testis / Q000502:physiology; D013739:Testosterone / Q000494:pharmacology*
chemical_list: D013739:Testosterone; D004958:Estradiol; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase