Gonadal Hormones in the Regulation of Methionine Adenosyltransferase Levels in Rat Liver ∗

Summary

The effects of gonadectomy and the administration of male or female hormones on the hepatic level of methionine adenosyltransferase have been studied in the rats of both sexes. It was found that the sex difference in the level of this enzyme can be attributed to the action of both estrogens and androgenic-anabolic hormones. Ovariectomy decreased the enzyme level, whereas the administration of 17β-estradiol or diethylstilbestrol, but not progesterone, reversed the effect of ovariectomy. Estradiol also raised the enzyme level in intact male rats to that of the female. Adrenalectomy had no effect on the response of the enzyme to estradiol. Castration of the male resulted in an increase in the activity of methionine adenosyltransferase, and the administration of androgenic-anabolic hormones brought the elevated activity down to the normal level of intact males or even lower. Adrenalectomy did not abolish the effect of castration. 17α-Ethyl-19-nortestosterone and 1-methyl-δ¹-androstenolone were more effective in this respect than testosterone, 17α-methyl-δ⁵-androstene-3β,17/β-diol and 5α-androstan-17β-ol-3-one. The effect of the steroids in decreasing methionine adenosyltransferase activity seems to be associated with their anabolic rather than their androgenic action.