Expression of the 17β-hydroxysteroid dehydrogenase type 5 mRNA in the human brain

An enzyme-mediated metabolism of androgens and estrogens including 17 beta -HSD activity in the brain of vertebrates was discovered similar to 30 years ago. Mainly 5 alpha -reductase and aromatase have been studied in detail. Recently we could demonstrate reductive and oxidative 17 beta -HSD activity as well as considerable mRNA expression of the 17 beta -HSD types 3 and 4 in the human brain. In the present study, we report on 17 beta -HSD type 5 mRNA expression in brain tissue of women and men. Data analysis did not reveal sex specific differences. but we determined a significantly higher mRNA concentration in the subcortical white matter (SC) than in the cerebral cortex (CX). Investigation of reductive 17 beta -HSD in vitro activity with 2 muM androstenedione as the substrate revealed no sex specific differences. Testosterone formation was significantly higher in SC than in CX. Moreover. enzyme activity was significantly higher in brain tissue of adults compared to that of children. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.