The Role of Development and Adrenal Steroids in the Regulation of the Mineralocorticoid Receptor Messenger RNA

Summary The ontogeny, adrenal-feedback regulation and regional distribution of the mineralocorticoid receptor (MR) mRNA were examined in the rat brain and kidney. In the kidney, MR mRNA levels in the adult were only 25-30% of the neonatal concentration. Adrenalectomy caused a 35% increase in total brain MR mRNA and a 94% increase in kidney MR mRNA levels. Examination of the regional distribution of the MR mRNA within the brain revealed that the hippocampus had the highest levels, and the mRNA abundance increased after adrenalectomy. The administration of dexamethasone to intact animals resulted in a significant reduction of MR mRNA in the kidney of neonatal rats but not in the brain. These data indicate that there are developmental changes in MR gene expression in kidney and that adrenal steroids can modulate MR gene expression in both the brain and kidney.