Abstract
Activity of the flavin-containing monooxygenase (EC 1.14.13.8, N,N-dimethylaniline N-oxidizing) was measured in liver, kidney, and lung homogenates obtained from control; gonadectomized; and testosterone-, β-estradiol-, and progesterone-pretreated CF-1 mice. The sex-related differences in liver microsomal N-oxidase activity described by Wirth and Thorgeirsson [Biochem. Pharmacol. 27:601-603 (1978)] appeared to be due primarily to testosterone repression of the liver enzyme. Activity, low in the adult male, rose significantly upon castration but returned to control levels upon testosterone replacement therapy. Activity of female liver, only marginally affected by ovariectomy, was markedly depressed by testosterone but rose slightly upon progesterone administration. In contrast to liver, testosterone appears to increase the amount of monooxygenase in kidney. Activity in this organ in sexually intact males was depressed by castration or by estradiol administration. The total amount of enzyme also increased following testosterone administration to gonadectomized or sexually intact females. Sex-related differences in lung N-oxidase activities could not be detected, and activity in this organ was not affected by gonadectomy or hormone pretreatment.
ACKNOWLEDGMENT We are indebted to Dr. Claude Desjardins, in our Zoology Department, for providing animals, the use of animal room facilities, and his expert supervision of all surgical procedures.
- Copyright © 1981 by The American Society for Pharmacology and Experimental Therapeutics
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