5α-还原酶活性在人与大鼠附睾不同部位的分布

Distribution of the 5αreductase isozyme activities in different segments of rat and human epididymis

为进一步了解５α－还原酶对附睾功能和精子成熟过程的作用，将大鼠及人附睾按头、体、尾分段分别制备匀浆，用已建立的５α－还原酶（５α－Ｒ）活性测定方法，测定胞浆、微粒体及核内５α－Ｒ．Ｉ、Ｉ型同功酶的活性分布。结果：（１）大鼠附睾５α－Ｒ活性分布与人附睾细胞核中５α－Ｒ活性分布一致，呈头高、尾低梯度递减（Ｐ＜０．０１），而微粒体及胞浆中不完全一致，体部较高、尾部最低（Ｐ＜０．０５）。（２）人与大鼠附睾５α－Ｒ活性在核及微粒体中高于胞浆，且微粒体与胞浆之间有相关性（ｒ＝０．８７５９）。（３）大鼠Ｉ、Ｉ型同功酶之间活性无明显差异（Ｐ＞０．０５），而人微粒体中５α－Ｒ．Ｉ型同功酶占优势。５α－Ｒ活性的这种分布特点与精子在附睾中逐步成熟过程相一致，提示５α－Ｒ可能是调节附睾精子成熟的重要核因子之一。

 Objectives: To study the distribution of the 5αreductase (5αR.)isozyme activities in subcellular fractions of different segments of the epididymis.Design: Experimental study on rat and human epididymis.Settings: The Endocrinology Laboratory of National Research Institute for Family Planning.Methods: Measurement of the 5αreductase isozyme activities in cytoplasm,microsome and nucleoplasm of different segments of rat and human epididymis.Results: (1)The 5αR.isozyme activities were similar in the rat and human epididymal nucleoplasm showing a gradient decrease from caput to cauda of the epididymis( P<0.01).The activities in microsome and cytoplasm were unidentical.The isozyme activities were highest in the corpus and lowest in the cauda (P<0.05)of human epididymis.(2)The activities of 5αR.isozymes in the nucleoplasm and microsome fractions of human and rat epididymis were more than those in the cytoplasm.There is a relationship between the microsome and the cytoplasm.(r=0.8759).(3)While no significant differences in I and II isozyme activities were observed in the rat epididymis,isozyme II activity seemed to be dominated in microsomal fractions of the corresponding segments of human epididymis.Conclusion: The distribution characteristics of the isozyme activities appear to be accordant with the progression of sperm maturation in the epididymis suggesting that 5αR.isozyme may be one of the essential nuclear factors regulating sperm maturation in the epididymis.The mechanism by which 5αR.isozymes regulate sperm maturation remains further study.