EXPRESSION OF MANGANESE SUPEROXIDE-DISMUTASE MESSENGER-RNA IN THE RATADRENAL-CORTEX IS ASSOCIATED WITH THE OCCURRENCE OF MITOCHONDRIAL VESICULAR CRISTAE

To investigate the possible role of manganese superoxide dismutase (Mn -SOD) in steroidogenesis, we studied the expression of Mn-SOD mRNA in the adrenal gland and ovaries of normal and hypophysectomized rats by in situ hybridization. Very strong expression of Mn-SOD mRNA was detec ted in the zona fasciculata and the zona reticularis of the rat adrena l cortex. The expression was very low in the zona glomerulosa, and was almost negative in the adrenal medulla. The mRNA levels in the adrena l cortex and the ovaries were markedly reduced 4 days after hypophysec tomy, Marked adrenocortical atrophy occurred 14 to 24 days after the o peration, while levels of Mn-SOD mRNA in the cortex remained low. Mito chondrial structure in the fasciculata cells of normal and hypophysect omized rats were compared by electron microscopy. Mitochondria in the fasciculata cells of normal rats were characterized by dense vesicular cristae. Four days after hypophysectomy, the cristae became tubulo-ve sicular in form and their density decreased significantly, Elongated m itochondria with tubular cristae appeared. Oval mitochondria with a fe w tubulo-vesicular cristae were present in these cells 14 days after t he operation. Our results are consistent with the hypothesis that high Mn-SOD levels might play an important role in the regulation of stero idogenesis. The possible roles of superoxide radicals and hydrogen per oxide in the formation of vesicular cristae in the mitochondria are di scussed with respect to steroidogenesis.