Sex difference in rat liver uric acid metabolism.

Mature female rat livers have a greater uricase activity when measured in vitro than do the livers of mature males. This sex difference is not exhibited by the livers of immature rats, wherein the level of enzyme activity found is essentially that of the mature male. Injection of estradiol-17β into mature males increases the liver uricase activity, whereas injection of testosterone propionate into females decreases this activity. Gonadectomy of either sex has little significant effect. Adrenalectomy reduces the measured uricase activity in both sexes, but does not eliminate the sex difference. Hypophysectomy reduces liver uricase activity in males and females and abolishes the sex difference. Thyroidectomy has no effect on uricase levels, but injection of T4 into female thyroidectomized rats reduces enzyme activity. Injection of estradiol-17β and of GH into hypophysectomized animals lowers the uricase activity; LH and FSH have no effect. ACTH administered to intact rats is ineffective. The results suggest...