Effects of adrenal steroid hormones on mitochondrial maturation during the late fetal period.

In the present work, we described the perinatal changes in mitochondrial maturation that contribute to metabolic development in the rat kidney. We focused on cytochrome-c oxidase activity and gene expression from the last three days of gestation to one day after birth. The role of adrenal steroids in the development of cytochrome-c oxidase expression and of mitochondrial DNA content was also investigated by studying the effects of fetal adrenalectomy. During the perinatal period, the developmental pattern of the cytochrome-c oxidase enzymatic complex exhibited parallel increases in transcript levels, protein content and enzyme activity, suggesting a transcriptional regulation of this enzyme. Adrenalectomy led to a decrease in fetal kidney cytochrome-c oxidase messengers and mtDNA content while administration of dexamethasone restored normal levels. In contrast, mtDNA content was unchanged in liver and heart after adrenalectomy whereas levels of cytochrome-c oxidase transcripts were controlled by adrenal steroids in liver but not in heart. These results indicate that adrenal steroid hormones contribute to the regulation of perinatal maturation of mitochondria in rat kidney and that these hormones are involved in the fetal mitochondrial biogenesis in a tissue-specific manner.