Effects of adrenocorticotropic hormone and dexamethasone on adrenal and hepatic α-tocopherol concentrations

Studies were done to determine the effects of ACTH treatment on adrenal α-tocopherol (α-T) concentrations in female rats. Administration of dexamethasone (DEX) to inhibit endogenous ACTH secretion increased whole adrenal α-T levels as well as the fractional amount in adrenal cytosol. Adrenal ascorbic acid (AA) concentrations were unaffected by DEX. DEX treatment also had no effect on hepatic AA content but decreased α-T concentrations in the liver. The subcellular distribution of α-T in the liver was not altered by DEX. Administration of ACTH to DEX-treated animals decreased adrenal α-T content and restored the pattern of subcellular distribution to that seen in controls. ACTH had no effect on hepatic α-T concentrations or subcellular distribution. ACTH treatment also had no effect on AA concentrations in adrenals or livers. The results demonstrate that ACTH has a role in the regulation of adrenal α-T but the mechanism(s) involved remain to be determined. The data also indicate that glucocorticoids such as DEX directly influence hepatic α-T levels independent of their effects on ACTH secretion.