目的 研究低雄激素对心肌组织结构的影响。方法 雄性SD大鼠随机分为对照组（n=8）、去势组（n=7）和雄激素替代组(n=8)。对照组进行假去势手术；去势组进行去势手术；雄激素替代组进行去势手术后肌肉注射十一酸睾酮替代治疗。10周后取各组大鼠血清，放射免疫法测定血清睾酮浓度；取各组大鼠心肌组织，苏木精-伊红染色后行光学显微镜观察；透射电子显微镜观察心肌超微结构。结果 与对照组和雄激素替代组相比，去势组血清睾酮浓度显著降低（P<0.01）。光学显微镜观察显示去势组心肌细胞肿胀肥大、变性，核明显增大，心肌纤维排列紊乱，断裂、溶解，收缩呈波浪状；电子显微镜观察可见去势组心肌纤维排列不规则，断裂、溶解，肌纤维间糖原、脂肪滴聚集，线粒体肿胀，线粒体大部分嵴不清晰，细胞闰盘增宽。与去势组相比，雄激素替代组病理改变明显减轻。结论 去势后雄性大鼠心肌出现明显的组织病理损伤，外源性睾酮替代治疗可以一定程度上改善病变，低雄激素水平对男性心肌有一定的损伤作用。

Objective To investigate the influence of low androgen on myocardial structure of male rats. Methods Male SD rats were randomly divided into control group (n=8), castration group (n=7) and androgen replacement group (n=8). Rats in control group underwent sham castration, those in castration group were castrated, and those in replacement group were given testosterone undecanoate after castration. Ten weeks later, serum concentration of testosterone was measured by radioimmunoassay. Pathological changes of myocardial tissues were observed by light microscopy and electron microscopy. Results Serum concentration of testosterone in castration group was significantly lower than those in control group and androgen replacement group (P<0.01). Light microscopy revealed that in castration group, there were myocardial swelling, hypertrophy, degeneration and nucleus enlargement, the nuclei significantly enlarged, the myocardial fibers fractured, dissolved, contracted and became wavy, and arranged in disorder. Electron microscopy revealed that in castration group, myocardial fibers arranged irregularly, fractured and dissolved, the glycogen and flat drop between muscle fibers accumulated, mitochondria swelled, most of the ridges in mitochondria were not clear, and the intercalated disk widened. Compared with castration group, the above-mentioned pathological changes in androgen replacement group were significantly lessened. Conclusion Obvious myocardial histopathological injury may occur in male rats after castration, and exogenous testosterone replacement therapy may work in some degree. Low androgen may do harm to myocardium of males.