In order to confirm the relationship between mitochondrial GSH-PO and steroidogenesis in the rat adrenal cortex, we have studied the immunocyto-chemical localization of GSH-PO in the rat adrenocortical cells of Metopiron administration, which blocks the conversion of deoxycorticosterone to corticosterone. In the control rat adrenocortical cells, mitochondrial GSH-PO was mainly localized in lipid-depleted compact cells, of inner fasciculata cells, but not zona glomerulosa and zona reticularis cells. By Metopiron administration, the adrenal cortex was markedly hypertrophic. Immunohistochemically, GSH-PO was observed in outer fasciculata cells and intracellular localization of GSH-PO was mainly observed in cytosol (cytosol GSH-PO). However, mitochondrial GSH-PO was less than that in the control rat adrenocortical cells.
Based on our findings, it is strongly suggested that mitochondrial GSH-PO may be a very important enzyme for steridogenesis, especially, corticosterone biosynthesis.