The physiological significance and the change of the neurosteroid-producing enzyme in the brain under stress conditions.

类固醇5 α-还原酶是将许多具有C-4，5双键和C-3酮的类固醇转化为5 α-还原代谢物的酶，并且两种同工酶中的1型存在于大脑中。我们通过在体外应激条件下（即无血清培养基）培养含5 α-还原酶的大鼠C6胶质瘤细胞，以化学方法研究了酶表达和细胞外观的变化。5 α-还原酶在有血清培养基中的表达定位于核周区，而在无血清培养基中的表达则定位于胞浆区。两种培养条件下，GFAP和CNX 4的表达量相同。在无血清培养液中，细胞形态呈多极化，在有血清培养液中，细胞形态呈纺锤形。然而，5 α-还原酶mRNA的表达与血清的存在无关。5 α-还原酶表达的免疫组织化学变化是由细胞内酶定位的变化引起的，而不是由酶量引起的。在肾上腺中，被认为参与了应激反应，5 α-还原酶定位于腺的束状层至网状层，去除性腺后酶的染色强度增加，补充睾酮后酶的染色强度降低或雌二醇。光镜和电镜结果表明，该酶定位于周围神经系统雪旺细胞和卫星细胞的胞质中。

Steroid 5alpha-reductase is the enzyme that converts a number of steroids with a C-4,5 double bond and C-3 ketone to 5alpha-reduced metabolites, and the type 1 of two isozymes is present in the brain. We investigated immunohistochemically the change of the enzyme expression and the cellular appearance of 5alpha-reductase-containing rat C6 glioma cells by culturing these cells in vitro in stress conditions, that is, the serum-free medium. The expression of 5alpha-reductase was located in the perinuclear region under the serum-supplemented medium, but distributed in the cytoplasmic region under the serum-free medium. The expression of both GFAP and CNPase was the same between the two culture conditions. The cellular form was spinde in the serum-supplemented medium, and became hypertrophic and multipolar in the serum-free medium. However, the expression of 5alpha-reductase mRNA was the same indifferent of the presence of serum. The immunohistochemical change of 5alpha-reductase expression was induced by the change of enzyme localization within the cells, but not by the enzyme quantity.In the adrenal gland, which is thought to be involved in the stress reactions, 5alpha-reductase was located in the fascicular to reticular layer of the gland and the staining intensity of the enzyme increased after the removal of gonads and decreased by the supplementation of testosterone or estradiol. The enzyme was shown to be located by light and electron microsopy in the cytoplasm of Schwann cells and satellite cells in the peripheral nervous system.