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目的:研究壳寡糖(COS)对大负荷运动大鼠心肌组织的保护作用。方法:将36只3月龄SPF级SD雄性大鼠随机分为正常对照组、耐力运动组和壳寡糖组,每组12只。耐力运动组和COS治疗组进行6周的跑台训练。24 h后处死大鼠,迅速取出心脏,在光镜和透射电镜下分别观察大鼠心肌组织的形态结构。测定心肌组织和血清超氧化物歧化酶(SOD)和丙二醛(MDA)的水平,SOD活性采用黄嘌呤氧化酶法测定,MDA含量采用TBA缩合比色法测定。结果:COS组大鼠心肌SOD活性(246.38±0.79)较运动组(138.61±1.17)显著增高(P<0.05),而血清SOD活性(67.92±18.47)较运动组(98.79±16.10)显著降低(P<0.05);心肌和血清MDA含量(3.64±0.19和4.50±0.74)均较运动组(6.87±0.34和7.86±0.46)显著降低(P<0.05)。COS治疗组大鼠心肌组织和血清中SOD的活性及MDA的含量与正常对照组比较差异无显著性。光镜下观察,运动组大鼠心肌细胞出现不同程度的水肿、变性和坏死;电镜下观察,耐力运动组大鼠心肌细胞损伤明显,肌原纤维模糊、断裂甚至坏死,线粒体肿胀等有形态学改变。COS治疗组大鼠心肌损伤的程度与耐力运动组比较明显减轻,而与正常对照组比较心肌组织的形态结构无明显变化。结论:大负荷运动可导致大鼠心肌组织、血清抗氧化功能指标改变,心肌组织损伤。COS可提高大负荷运动大鼠心肌组织的抗氧化功能,维持心肌组织的正常形态结构。
Objective: To study the protective effect of chitooligosaccharides (COS) on myocardium of rats during heavy-duty exercise. Methods: Thirty-six male Sprague-Dawley (SD) rats of 3 months old were randomly divided into normal control group, endurance exercise group and chitosan oligosaccharide group, with 12 rats in each group. Endurance exercise group and COS treatment group for 6 weeks treadmill training. After 24 h, the rats were sacrificed, and the heart was removed rapidly. The morphological changes of myocardial tissue were observed under light microscope and transmission electron microscope. The level of SOD and MDA in myocardial tissue and serum were determined. The SOD activity was measured by xanthine oxidase method. The content of MDA was measured by TBA condensation colorimetry. Results: Compared with exercise group, the activity of SOD in the COS group was significantly higher (246.38 ± 0.79) than that in the exercise group (138.61 ± 1.17) (P <0.05), while the activity of serum SOD was significantly lower (67.92 ± 18.47) than that in the exercise group (98.79 ± 16.10) P <0.05). The content of MDA in myocardium and serum were significantly lower (3.64 ± 0.19 and 4.50 ± 0.74) than those in exercise group (6.87 ± 0.34 and 7.86 ± 0.46 respectively) (P <0.05). The activity of SOD and the content of MDA in myocardial tissue and serum of COS treatment group were not significantly different from those in normal control group. Under light microscope, the cardiomyocytes of rats in exercise group showed different degrees of edema, degeneration and necrosis. Electron microscopy showed that myocardial cells of rats in endurance exercise group were damaged obviously, myofibrillar cells were blurred, ruptured or even necrotic, mitochondrial swelling and other morphological changes change. The degree of myocardial injury in the COS-treated group was significantly reduced compared with the endurance exercise group, but there was no significant change in the myocardial structure compared with the normal control group. Conclusion: Heavy-load exercise can lead to changes of anti-oxidative function and myocardial injury in myocardial tissue and serum of rats. COS can improve the anti-oxidative function of myocardial tissue in rats under heavy load and maintain the normal morphological structure of myocardial tissue.