Metabolism of [4- 14C]estrone in hamster and rat hepatic and renal microsomes: Species-, sex- and age-specific differences

Abstract

The metabolism of [4- 14C]estrone (E 1) was examined in liver and kidney microsomes of adult castrated male and ovariectomized female hamsters and rats and in neonatal and immature hamster renal microsomes. In castrated male hamster liver microsomes, E 1 was metabolized extensively to six major metabolites; 15β-hydroxyestrone, 7α-hydroxyestrone, 6α-hydroxyestrone, 6β-hydroxyestrone, 2-hydroxyestrone, and Δ(9,11)-dehydroestrone, and a nonpolar fraction. Six minor metabolites of E 1 were also detected. In contrast, kidney microsomes derived from castrated male hamsters metabolized E 1 to mainly 17β-estradiol, 2- and 4-hydroxyestrone, 6α-hydroxyestrone, 6β-hydroxyestrone and one monohydroxyestradiol metabolite. However, 16α-hydroxyestrone was not detected. A variable, but low amount of estriol was also found. Interestingly, the quantity of 2-hydroxyestrone found in kidney microsomes of the hamster represented 26% of the total amount of metabolites formed, whereas in liver microsomes, only 9% of the overall metabolism resulted in the formation of 2-hydroxyestrone. The ability of kidney microsomes of female ovariectomized hamsters and two different rat strains to metabolize E 1 was 5.9- and 9.4-fold lower, respectively, compared to renal microsomes of male castrated hamsters. The onset of oxidative metabolism in newborn hamster kidneys during development was also assessed. The results indicate that the oxidative metabolism of [ 14C]E 1 in renal microsomes of newborn hamsters was 20-fold less than in kidney microsomes of adult hamsters. While catechol E 1 metabolites were essentially negligible in hamster kidneys of these ages, it was evident that the conversion of E 1 to estradiol via 17β-hydroxysteroid dehydrogenase resembles levels seen in the adult animals. Between the age of one and two months, the male hamster kidney exhibited the capacity to metabolize E 1 at levels seen in fully mature adult hamsters.