Khanna M, Qin K N, Cheng K C
Department of Pediatrics, Cornell University Medical College, New York, NY 10021, USA.
J Steroid Biochem Mol Biol. 1995 Jun;53(1-6):41-6. doi: 10.1016/0960-0760(95)00019-v.
3 alpha-Hydroxysteroid dehydrogenase in the brain is responsible for production of neuroactive tetrahydrosteroids that interact with the major inhibitory gamma-aminobutyric acid receptor complexes. Distribution of 3 alpha-hydroxysteroid dehydrogenase in different regions of the brain in rats was evaluated by activity assay and by Western immunoblotting using a monoclonal antibody against liver 3 alpha-hydroxysteroid dehydrogenase as the probe. The olfactory bulb was found to contain the highest level of 3 alpha-hydroxysteroid dehydrogenase activity, while moderate levels of the enzyme activity were found in other regions such as cerebellum, cerebral cortex, hypothalamus and pituitary. Some activity was found in the rest of the brain such as amygdala, brain stem, caudate putamen, cingulate cortex, hippocampus, midbrain, and thalamus. The protein levels of 3 alpha-hydroxysteroid dehydrogenase in different regions of the brain as detected by Western immunoblotting are comparable to those of the enzyme activity. We used the rat cDNA as the probe to screen a human liver lambda gt11 cDNA library. A total of four different cDNAs were identified and sequenced. One of the cDNAs is identical to that of the human chlordecone reductase cDNA except that our clone contains a much longer 5'-coding sequence than previously reported. The other three cDNAs display high degrees of sequence homology to those of both rat 3 alpha-hydroxysteroid dehydrogenase and human chlordecone reductase. We are currently investigating the functional relationship between the enzymes encoded by these human cDNAs and 3 alpha-hydroxysteroid dehydrogenase.
大脑中的3α-羟基类固醇脱氢酶负责产生与主要抑制性γ-氨基丁酸受体复合物相互作用的神经活性四氢类固醇。通过活性测定以及使用抗肝脏3α-羟基类固醇脱氢酶单克隆抗体作为探针的Western免疫印迹法，评估了大鼠大脑不同区域中3α-羟基类固醇脱氢酶的分布。发现嗅球中3α-羟基类固醇脱氢酶活性水平最高，而在小脑、大脑皮层、下丘脑和垂体等其他区域发现该酶活性处于中等水平。在大脑的其他部位如杏仁核、脑干、尾状壳核、扣带回皮层、海马体、中脑和丘脑也发现了一些活性。通过Western免疫印迹法检测到的大脑不同区域中3α-羟基类固醇脱氢酶的蛋白质水平与酶活性水平相当。我们使用大鼠cDNA作为探针筛选人肝脏λgt11 cDNA文库。总共鉴定并测序了四个不同的cDNA。其中一个cDNA与人类十氯酮还原酶cDNA相同，只是我们的克隆包含比先前报道长得多的5'-编码序列。其他三个cDNA与大鼠3α-羟基类固醇脱氢酶和人类十氯酮还原酶的cDNA显示出高度的序列同源性。我们目前正在研究这些人类cDNA编码的酶与3α-羟基类固醇脱氢酶之间的功能关系。
