title: Steroid 21-hydroxylase expression in cultured rat astrocytes.
abstract: Over the past decade or so it has become widely recognised that the brain is a significant steroidogenic organ. Many publications have highlighted the ability of the brain to synthesise and interconvert a large number of steroid products including cholesterol, progesterone and testosterone. In this study, in vitro experiments were performed to determine if 21-hydroxylation of steroids is undertaken by rat brain astrocytes in culture. This is a common reaction that occurs in the adrenal gland and other organs in mammals, catalysing the conversion of pregn-4-ene-3,20-dione (progesterone) to 21-hydroxypregn-4-ene-3,20-dione (deoxycorticosterone). Previous reports have indicated that 21-hydroxylation occurs within the rat brain, however, the precise identity of the cells expressing 21-hydroxylase has not yet been determined. Several metabolites, such as 5alpha-pregnan-3alpha-ol-20-one (tetrahydroprogesterone) and 3alpha,21-dihydroxy-5-pregnan-20-one (tetrahydrodeoxycorticosterone) were of particular interest because of their modulatory role in neuronal function, such as their agonist activity at gamma-aminobutyric acid (GABA(A)) receptors. Evidence was obtained for the expression of peripheral 21-hydroxylase enzyme (P450c21) in cultured rat brain astrocytes by a combination of mass spectroscopy and molecular biology techniques. This is a significant finding as expression of 21-hydroxylase within astrocytes may be indicative of a wider role for these cells in modulating neuronal behaviour.
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000201:enzymology*; D002478:Cells, Cultured; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013255:Steroid 21-Hydroxylase / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics
chemical_list: D013255:Steroid 21-Hydroxylase