Leung P S, Fung M L, Sernia C
Department of Physiology, The Chinese University of Hong Kong, Shatin, Hong Kong.
Regul Pept. 2001 Jan 12;96(3):143-9. doi: 10.1016/s0167-0115(00)00169-5.
The presence of an intrinsic renin-angiotensin system (RAS) in the rat epididymis has been previously established by showing the expression of several key RAS components, and in particular angiotensinogen, the indispensable element for the intracellular generation of angiotensin II. In this study, the possible involvement of this local epididymal RAS in the testicular effects of chronic hypoxia was investigated. Semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR), Western blotting and by in situ hybridization histochemistry of the rat epididymis were used to show changes in localization and expression of angiotensinogen. Results from RT-PCR analysis demonstrated that chronic hypoxia caused a marked decrease (60%) in the expression of angiotensinogen mRNA, when compared with that in the normoxic epididymis. Western blot analysis demonstrated a less decrease (35%) in the expression of angiotensinogen protein. In situ hybridization histochemistry showed that the reduced angiotensinogen mRNA in chronic hypoxia was specifically localized to the epididymal epithelium from the cauda, corpus and caput regions of the epididymis; a distribution similar to that of normoxic rats. It was concluded that chronic hypoxia decreases the transcriptional and translational expression of angiotensinogen, and thus local formation of angiotensin II, in the rat epididymis.
先前通过显示几种关键肾素 - 血管紧张素系统（RAS）成分的表达，特别是血管紧张素原（血管紧张素II细胞内生成所必需的元素），证实了大鼠附睾中存在内源性RAS。在本研究中，研究了这种局部附睾RAS可能参与慢性缺氧对睾丸的影响。采用大鼠附睾的半定量逆转录聚合酶链反应（RT-PCR）、蛋白质印迹法和原位杂交组织化学方法，以显示血管紧张素原的定位和表达变化。RT-PCR分析结果表明，与常氧附睾相比，慢性缺氧导致血管紧张素原mRNA表达显著降低（60%）。蛋白质印迹分析表明血管紧张素原蛋白表达降低幅度较小（35%）。原位杂交组织化学显示，慢性缺氧时血管紧张素原mRNA减少特异性定位于附睾尾部、体部和头部区域的附睾上皮；其分布与常氧大鼠相似。得出的结论是，慢性缺氧会降低大鼠附睾中血管紧张素原的转录和翻译表达，从而减少血管紧张素II的局部生成。
