In vitro Metabolism of Steroid Hormones by Rodent Submaxillary Gland

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  • ゲッシ類の顎下腺におけるステロイドホルモンの代謝
  • ゲッシルイ ノ ガッカセン ニ オケル ステロイド ホルモン ノ タイシャ 2
  • 2. Changes in Activities of 5-Reductase and 17-Hydroxysteroid Dehydrogenase of Rat Submaxillary Gland with Age
  • 2. ラツト顎下腺のステロイド代謝酵素活性の週齢にともなう変化

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In our previous report, the in vitro metabolism of androstenedione and testosterone by the submaxillary glands of adult male rats was demonstrated. This paper deals with the metabolism of these two androgens by the submaxillary glands of younger rats and changes of the enzymes involved in their metabolism with age. Submaxillary gland homogenates of male rats at 1, 2, 3, 4, 5, 7 and 10 weeks of age were incubated with [1, 2, 6, 7-3H] androstenenedione and [4-14C] testosterone in the presence of NADPH for 60min. Identification of metabolites was made by thin layer chromatography, derivative formation and radiorecrystallization to constant specific activity or constant 3H:14C ratio. Activity of an enzyme was expressed as the yield of the product in the reaction in which this enzyme was involved. The metabolism of androstenedione and testosterone in the submaxillary glands of these rats was largely reductive: these two androgens were rapidly converted to 5α-androstane-3, 17-dione, 5α-dihydrotesyosterone, androsterone and 5α-androstane-3α, 17β-diol. In this case, 5α-reductase and 17β-hydroxysteroid dehydrogenase were involved in these reactions. Activity of 5α-reductase, the sum of yield of 5α-androstan-3, 17-dione, 5α-dihydrotestosterone, androsterone and 5α-androstane-3α, 17β-diol from androstenedione or testosterone, decreased gradually with advancing age from 1 to 5 weeks after birth and, thereafter, increased at 7 and 10 weeks after birth. When androstenedione was used as a substrate, activity of 17β-hydroxysteroid dehydrogenase, the sum of yield of 5α-dihydrotestosterone, testosterone and 5α-androstane-3α, 17β-diol, was nealy constant in the range from l to 5 weeks after birth and became high at 7 and 10 weeks after birth. When testosterone was used as a substrate, activity of this enzyme, the sum of yield of 5α-androstane-3, 17-dione, androstenedione and androsterone, decreased with increasing age.

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