Effect of extract of maize plumule on free radical metabolism and ultrastructure of myocardium in aging mice

Chinese. 小鼠颈背部皮下注射D-半乳糖生理盐水溶液（125 mg/(kg•d)）诱导其衰老，同时分别灌胃10,20和40 mg/(kg•d)玉米幼芽提取物（Extract of maize plumule,EMP），每日1次，连续处理42 d后，测定心肌组织超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GSH-Px）活性及丙二醛（MDA）和一氧化氮（NO）的含量，并用透射电镜观察心肌细胞超微结构，研究EMP对D-半乳糖致衰老小鼠心肌自由基代谢和超微结构的影响。结果表明，与对照组相比，D-半乳糖能明显的降低小鼠心肌组织中的SOD、CAT和GSH-Px活性，提高MDA、NO含量；与衰老模型组比较，20 mg/kg EMP处理组小鼠心肌组织的SOD、CAT和GSH-Px活性均极显著升高，MDA和NO含量均极显著降低；与对照组相比，衰老模型组小鼠的心肌Z线变宽、模糊，肌原纤维断裂、溶解、凝集，线粒体肿胀、空泡化、嵴消失；20 mg/kg EMP处理组的以上病变均有明显的改善。这表明20 mg/kg的EMP具有增强衰老小鼠心肌抗氧化酶活性，改善心肌自由基代谢，保护心肌细胞超微结构的作用。

English. Effect of extract of maize plumule (EMP) on free radical metabolism and ultrastructure of myocardium in aging mice induced by D-galactose was investigated. Physiological saline solution of D-galactose was applied in subcutaneous injection on the back of neck 125 mg/kg per day, once daily continuously for 42 days to induce the aging model. At the same time, EMP (10, 20 and 40 mg/kg) was given by gastric perfusion once daily continuously for 42 days too to study the activity of superoxide dismutase (SOD), Catalase (CAT), Glutathione peroxidase (GSH-Px) and the content of malondialdehyde (MDA) and nitric oxide (NO). Meanwhile, the ultrastructure of myocardium was observed under transmission electron microscope. The data show that D-galactose caused a significant decrease in the SOD, CAT and GSH-Px activity and increase in MDA and NO content versus control group. Compared with model group, mice treated with both D-galactose and EMP (20 mg/kg) obviously had a higher SOD, CAT and GSH-Px activity and lower MDA and NO content. Under transmission electron microscope, these pathological changes were observed in aging model group: Z-line broadening and illegibility; Myofilament fragmentation, dissolution, agglutination; Mitochondrion swelling, vacuolization, cristae vanishing. These pathological changes were significantly improved by EMP at a concentration of 20 mg/kg. The result indicates that 20 mg/kg EMP can increase the activity of anti-oxidation enzyme, improve free radical metabolism and protect ultrastructure of myocardium from oxidative stress in aging mice.