Analysis by immunocytochemistry and in situ hybridization of renin and its mRNA in kidney, testis, adrenal, and pituitary of the rat.

Renin gene expression in cells and tissues of the rat was examined by in situ hybridization histochemistry and immunocytochemistry. By using a mouse cDNA probe, hybridization histochemistry revealed renin mRNA in the renal juxtaglomerular cells, testicular Leydig cells, adrenal zona glomerulosa cells, the intermediate lobe of the pituitary, and scattered cells of the anterior lobe of the pituitary. With four separate antisera to mouse submaxillary renin, there was immunoreactivity in the renal juxtaglomerular cells. However, only one of the antisera stained the Leydig cells, a second stained the adrenal zona glomerulosa, a third stained the intermediate lobe of the pituitary, and a fourth stained scattered cells of the anterior lobe of the pituitary that were identified as gonadotrophs. The variations with the different antisera in detecting extrarenal renin are unexplained but could imply that posttranslational proteolysis or glycosylation of preprorenin varies in different tissues with consequent variations in immunoreactivity. The finding of renin mRNA and renin-like immunoreactivity in these tissues supports the notion that these tissues are sites for production of renin.