Estrogen metabolism in the (New Zealand black × New Zealand white)F₁ Murine model of systemic lupus erythematosus

Hepatic microsomal estrogen metabolism was analyzed in the (New Zealand black × New Zealand white)F₁ ([NZB × NZW]F₁) murine model of systemic lupus erythematosus. Both the estrogen 2‐hydroxylase activity (per mg microsomal protein) and the hepatic cytochrome P‐450 content were higher in premorbid (NZB × NZW)F₁ mice, as compared with similarly aged nonautoimmune mice. However, these differences were not associated with alterations in the relative formation of the 2‐hydroxylated and the 16α‐hydroxylated metabolites. The development of overt nephritis was associated with a decrease in estrogen metabolic activity, but not with any alteration in the distribution of estrogen metabolites. Thus, estrogen metabolism was not altered in premorbid (NZB × NZW)F₁ mice in a manner that would result in abnormal retention of hormonally active metabolites.