Development of drugs targeting neurosteroid-metabolizing enzymes

3α-羟基类固醇脱氢酶和20-α-类固醇脱氢酶参与了神经活性类固醇的合成和代谢。在人类中，存在一个20α-HSD和3个3-α-HSD(1-3型)，这些酶在神经类固醇代谢中的作用尚不清楚，但临床研究提供了证据，证明神经活性类固醇参与了经前综合征、月经癫痫和抑郁障碍等疾病。这项研究将以下六点集中在两种人类酶上，作为开发治疗这种疾病的新药的目标1。人体酶在神经类固醇代谢中的作用。这些酶的组织分布和底物特异性表明，在大脑中，20α-HSD可以灭活神经活性类固醇及其前体黄体酮，而3α-HSD 3型参与了神经活性类固醇的合成。寻找激活剂和抑制剂。仅3个α-HSD型…More-1被几种治疗药物和甲状腺素激活。在几种酶抑制剂中，苯溴马龙及其衍生物对20α-HSD有较强的特异性抑制作用，提示它们是开发药物的先导化合物。酶的结构-功能关系。对20个α-HSD和3个α-HSD的1型进行了定点突变研究，发现或推测它们的活性中心和激活剂和抑制剂的结合部位有几个氨基酸。20α-HSD的结晶学研究正在进行中。基因表达的调控。除3种α-HSD1型外，依拉昔酸均能促进这些酶在几种培养的人细胞中的表达。肝脏特异性3α-HSD1型的表达研究表明，三种肝细胞核因子调控该酶基因的转录。遗传多态。对标本中3个α-HSD1型基因的表达进行分析，发现了一个编码低催化活性的酶的变异基因。利用细胞和动物转染酶或其基因的药物评价体系的建立利用细胞建立了该体系，但由于该酶的表达太少而不影响脑功能，利用动物模型无法实现该体系。将继续建立后一种制度。较少

3α-Hydroxysteroid dehydrogenase (HSD) and 20α-HSD in animal brains have been shown to be involved in the synthesis and metabolism of neuroactive steroids. In humans, one 20α-HSD and three 3α-HSDs (type 1 - 3) are present, and the roles of the enzymes in the neurosteroid metabolism are unknown, but clinical investigations provide evidence for an involvement of the neuroactive steroids in conditions such as premenstrual syndrome, catamenial epilepsy and depressive disorders. This study focused the following six points on the two human enzymes as targets for developing new drugs for management of such disorders.1. Roles of the human enzymes in the neurosteroid metabolism. Tissue distribution and substrate specificity for neurosteroids of the enzymes suggest that in the brain 20α-HSD inactivates the neuroactive steroids and their precursor, progesterone, and that 3α-HSD type 3 is involved in the synthesis of the neuroactive steroids.2. Search of activators and inhibitors. Only 3α-HSD type … More 1 was activated by several therapeutic drugs and thyroxine. Of several inhibitors for the enzymes, benzbromarone and its derivatives specifically and strongly inhibited 20α-HSD, which suggests that they are lead compounds to develop the drugs.3. Structure-function relationship of the enzymes. The site-directed mutagenesis study of 20α-HSD and 3α-HSD type 1 identified or suggested several amino acids in their active centers and binding sites for the activators and inhibitors. The crystallographic study of 20α-HSD is now in progress.4. Regulation of gene expression. Ethacrynic acid enhanced the expression of the enzymes, except 3α-HSD type 1 in several cultured human cells. The investigation of expression of liver-specific 3α-HSD type 1 indicated that three hepatocyte nuclear factors regulate the transcription of the enzyme gene.5. Genetic polymorphism. Analyses of expressed mRNA and gene for 3α-HSD type 1 in specimens identified a variant gene which encodes a enzyme with low catalytic activity.6. Establishment of evaluation system for drugs using cells and animals transfected with the enzymes or their genes The system using the cells was established, but that using the animal models could not be achieved, because the expression of the enzyme was too little to affect the brain function. The establishment of the latter system will be continued. Less