Localization of 11 beta-hydroxysteroid dehydrogenase type 2 in rat tissues: In situ studies

In the rat, the enzyme 11 beta-hydroxysteroid dehydrogenase 2 (11 beta HSD2) converts the glucocorticoid corticosterone into receptor-inactive Il-dehydrocorticosterone, thereby allowing preferential access of aldosterone to mineralocorticoid receptors (MR). The present study examines the distribution of this enzyme by in situ hybridization, using a homologous complementary RNA probe for 11 beta HSD2. 11 beta HSD2 messenger RNA was detected in classic epithelial aldosterone target tissues (kidney, salivary glands, and colon), the female reproductive system (ovary, oviduct, uterus, and placenta), and the adrenals; levels in heart, testis, and liver were below the limits of detection. We interpret the finding of 11 beta HSD2 expression in both classical MR-containing aldosterone target tissues and a variety of other tissues as evidence that in the rat, the enzyme may play physiological roles in addition to that of excluding glucocorticoids from epithelial MR.