DEXAMETHASONE-INDUCED HYPERGLYCEMIA IN OBESE A(VY)/A (VIABLE YELLOW) FEMALE MICE ENTAILS PREFERENTIAL INDUCTION OF A HEPATIC ESTROGEN SULFOTRANSFERASE

Sex steroid sulfotransferases (ST) sulfurylate and thus inactivate estrogens or androgens, producing an androgenized or estrogenized state in the liver. The expression of diabetes in a number of animal models is sexually dimorphic and has been associated with steroidal states. Although the viable yellow (A(vy)) mutation produces an insulin-resistant obesity syndrome in mice of both sexes, only males develop chronic hyperglycemia. Hyperglycemia was rapidly induced in A(vy)/a females by dexamethasone (dex). This treatment completely suppressed both endogenous plasma corticosterone and hepatic corticosterone-binding globulin (CBG) mRNA within 24 h. Hyperglycemia in dex-implanted A(vy)/a females was accompanied by aberrant shifts in hepatic androgen/ estrogen balance. This was effected by induction of estrogen sulfotransferase (EST) mRNA together with a > 10-fold increase in enzymatic activity. Similar dex-induced increases in androgen ST or phenol ST were not observed, Prior implantation of estrogen prevented development of hyperglycemia, The time-dependent spontaneous reversal of dex-induced hyperglycemia correlated with re-expression of CBG mRNA transcripts and reduced levels of EST transcripts and enzyme activity. Although dex-induced hyperglycemia was limited to A(vy)/a females, dex elicited hyperinsulinemia in lean a/a control mice of both sexes and exacerbated constitutive hyperinsulinemia in A(vy)/a males and females. In summary, dex-induced hyperglycemia in A(vy)/a females was associated with increased catabolism of hepatic estrogens mediated by induction of EST.