In vitro metabolism of steroid hormones by rodent submaxillary gland 2. changes in activities of 5 reductase and 17 hydroxy steroid dehydrogenase of rat submaxillary gland with age

Katsukawa, H.; Nakamura, T.; Tanabe, Y.

Japanese Journal of Zootechnical Science 51(3): 165-170


Accession: 005649912

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The metabolism of androstenedione [DIONE] and testosterone [T] by the submaxillary glands of young rats and changes of the enzymes involved in their metabolism with age are studied. Submaxillary gland homogenates of male rats at 1, 2, 3, 4, 5, 7 and 10 wk of age were incubated with [1,2,6,7-3H]androstenedione and [4-14C]testosterone in the presence of NADPH for 60 min. Identification of metabolites was made by TLC, 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 DIONE and T in the submaxillary glands of these rats was largely reductive: these 2 androgens were rapidly converted to 5.alpha.-androstane-3,17-dione, 5.alpha.-dihydrotestosterone, androsterone and 5.alpha.-androstane-3.alpha.,17.beta.-diol. In this case, 5.alpha.-reductase and 17.beta.-hydroxysteroid dehydrogenase were involved in these reactions. Activity of 5.alpha.-reductase, the sum of yield of 5.alpha.-androstane-3,17-dione, 5.alpha.-dihydrotesterone, androsterone and 5.alpha.-androstane-3.alpha.,17.beta.-diol from DIONE or T, decreased gradually with advancing age from 1-5 wk after birth and, thereafter, increased at 7 and 10 wk after birth. When DIONE was used as a substrate, activity of 17.beta.-hydroxysteroid dehydrogenase, the sum of yield of 5.alpha.-dihydrotestosterone, T and 5.alpha.-androstane-3.alpha.,17.beta.-diol, was nearly constant in the range from 1-5 wk after birth and became high at 7 and 10 wk after birth. When T was used as a substrate, activity of this enzyme, the sum of yield of 5.alpha.-androstane-3,17-dione, DIONE and androsterone, decreased with increasing age.