Development of drugs targeting neurosteroid-metabolizing enzymes

动物脑中的3α-羟基类固醇脱氢酶（HSD）和20α-HSD已被证实参与神经活性类固醇的合成和代谢。在人类中，存在1个20α-HSD和3个3α- hsd（1 - 3型），这些酶在神经类固醇代谢中的作用尚不清楚，但临床研究提供证据表明，这些神经活性类固醇参与了经前综合征、睡眠性癫痫和抑郁症等疾病。本研究将这两种人类酶作为开发治疗这类疾病的新药的靶点，集中在以下六个方面。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使神经活性类固醇及其前体黄体酮失活，3α- hsd 3型参与神经活性类固醇的合成。寻找活化剂和抑制剂。只有3α-HSD型，多种治疗药物和甲状腺素可激活More 1。在几种酶抑制剂中，苯溴马龙及其衍生物对20α-HSD具有特异性和较强的抑制作用，是开发该类药物的先导化合物。酶的结构-功能关系。对20α-HSD和3α-HSD 1型的定点诱变研究发现或提示了激活剂和抑制剂的活性中心和结合位点上的几个氨基酸。20α-HSD的晶体学研究正在进行中。基因表达的调控。乙酸能增强除3α-HSD 1型外的其他酶的表达。肝脏特异性3α-HSD 1型的表达研究表明，3种肝细胞核因子调控该酶基因的转录。遗传多态性。通过对标本中3α-HSD 1型mRNA和基因表达的分析，发现了一个编码低催化活性酶的变异基因。利用转染酶或其基因的细胞和动物建立药物评价体系。利用细胞建立了评价体系，但由于酶的表达太少，无法影响脑功能，无法实现动物模型的评价。后一种制度的建立将继续下去。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