Effects of Vitamin E on Steroidogenesis in Rat Zona Fasciculata-Reticularis Cells

Abstract

Vitamin E is an antioxidant which can prevent reduction in endothelial nitric oxide release in diabetic rat heart. However, the effects and action mechanisms of vitamin E on rat adrenal zona fasciculata-reticularis (ZFR) cells are still unclear. This study explored the effects of vitamin E on corticosterone release, the functions of cytochrome P450 side-chain cleavage enzyme (P450scc), and protein expression of steroidogenic acute regulator (StAR) protein and P450scc. ZFR cells were incubated with vitamin E in the presence or absence of adrenocorticotropin (ACTH), 8-bromo-cyclic 3': 5' adenosine monophosphate (8-Br-cAMP), 25-OH-cholesterol, pregnenolone, progesterone, or deoxycorticosterone at 37°C for 1 h or 3 h. The media were collected to measure the concentration of corticosterone or pregnenolone by radioimmunoassay (RIA). The cells were used to measure the StAR or P450scc protein expression by Western blotting analysis. The data demonstrated that [1] vitamin E inhibited ACTH-, 8-Br-cAMP-, or steroidogenic precursors-stimulated corticosterone release; [2] vitamin E increased the Michaelis constants of P450scc from 4.908 M to 11.997 M; [3] vitamin E might affect StAR protein expression.