Effect of steroid hormone treatment on aryl hydrocarbon hydroxylase activity in the Syrian hamster kidney

Abstract

Aryl hydrocarbon hydroxylase (AHH) activity was determined in castrate and intact male Syrian hamster kidney and liver microsomes following in vivo treatment with either diethylstilbestrol (DES) or 17β-estradiol as well as other steroid hormones. After 1 month of estrogen treatment, there was a 5-fold decline in AHH activity in castrated hamster kidneys compared with untreated castrate levels. the amount of AHH activity in the kidney was depressed more than 75% of untreated castrate levels even after the estrogen had been withdrawn for 6 days. Consistent with a nearly 2.5-fold higher renal AHH activity observed in intact male hamsters compared to castrates was the finding of a 1.7-fold elevation in the activity of this enzyme after treatment of castrated animals with androgen[5α-dihydrotestrosterone (5α-DHT)] for 1 month. Moreover, following withdrawal of estrogen from intact hamsters, the increase in AHH activity in the kidney essentially paralleled the rise in serum testosterone levels. In castrated animals, the depression of AHH activity by estrogen was partially reversed by concomitant 5α-DHT treatment. However, no appreciable changes were seen in liver AHH activity with androgen treatment in the presence or absence of estrogen. Similarly, the level of AHH activity, which was nearly 7- and 14-fold higher than intact and castrate kidney levels, respectively, was not altered by estrogen treatment. Neither progesterone nor cortisone had any effect on the levels of AHH activity in either the kidney or liver. Therefore, AHH activity in the male hamster kidney, but not the liver, is responsive to both estrogens and androgenic hormone.