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

类固醇5 - α还原酶是一种将含有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，大脑中存在两种同工酶的1型。采用免疫组化方法，在体外应激条件下，即无血清培养基中培养含5α -还原酶的大鼠C6胶质瘤细胞，观察其酶表达和细胞外观的变化。在无血清培养基中，5α -还原酶的表达分布在细胞质区，而在添加血清培养基中，5α -还原酶的表达位于核周区。两种培养条件下GFAP和CNPase的表达量相同。细胞形态在加血清培养基中呈纺丝状，在无血清培养基中呈肥厚多极化。血清的存在对5α -还原酶mRNA的表达没有影响。5 α -还原酶表达的免疫组化变化是由细胞内酶定位的变化引起的，而不是由酶的量引起的。在被认为参与应激反应的肾上腺中，5 α -还原酶位于腺体的束状至网状层，该酶的染色强度在去除性腺后增加，在补充睾酮或雌二醇后降低。光镜和电镜下发现该酶存在于周围神经系统的雪旺细胞和卫星细胞的细胞质中。

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.