梓醇对阿尔茨海默病大鼠模型大脑皮质保护作用

The protective effect of catalpol on cerebral cortex in an Alzheimer’s disease rat model

目的观察梓醇对阿尔茨海默病(AD)大鼠模型大脑皮质的保护作用。方法健康雄性Wistar大鼠36只,体质量范围为250~300 g,随机数字表法分为4组,每组9只:健康对照组、模型组、梓醇小剂量组、梓醇大剂量组。除健康对照组大鼠外,其余组大鼠均行右侧脑室定位注射β?淀粉样蛋白片段25?35(Aβ25?35)和腹腔注射D?半乳糖结合制备AD模型,然后梓醇小剂量组大鼠注射梓醇5 mg·kg^-1·d^-1,梓醇大剂量组大鼠注射梓醇10 mg·kg^-1·d^-1,健康对照组和模型组大鼠注射等容积0.9%氯化钠水溶液,连续腹腔注射给药7 d。Y?迷宫检测大鼠的学习指数,苏木精?伊红(HE)染色和透射电镜观察AD大鼠皮层结构,免疫组织化学染色观察大脑皮质胆碱能毒蕈碱受体M1亚型(M1受体)的表达,蛋白质印迹法(Western Blot)检测M1受体蛋白的含量。结果实验过程中模型组大鼠死亡1只,最终模型组n=8,其余组均n=9。与模型组比较,从造模后第14天开始,梓醇显著提高了大鼠的学习指数(第14天:小剂量组t=3.267,P=0.030 9,大剂量组t=4.648,P=0.009 7;第21天:小剂量组t=5.010,P=0.007 4,大剂量组t=4.614,P=0.009 9),第14天4组大鼠的学习指数分别为(5.6±0.2),(2.6±0.3),(3.7±0.5),(4.4±0.6);第21天4组大鼠的学习指数各组分别为(6.3±0.8),(4.1±0.5),(5.3±0.4),(5.8±0.8)。HE染色可见模型组大鼠大脑皮质结构有损伤性表现,透射电镜检查见大脑皮质神经元细胞内线粒体、粗面内质网、核染色质等异常改变,梓醇干预组神经元的结构显著改善。免疫组织化学染色可见模型组大鼠大脑皮质M1受体染色浅,神经元数目减少,M1受体蛋白表达下调,梓醇能够显著上调M1受体蛋白表达(与模型组比较,小剂量组t=3.983,P=0.016 4;大剂量组t=6.694,P=0.002 6),4组大鼠M1受体蛋白表达分别为100%,64.75%,74.63%,85.74%。结论梓醇能够改善AD大鼠大脑皮质结构异常,升高M1受体表达。

Objective To observe the protective effect of catalpol on cerebral cortex in an Alzheimer’s disease(AD)rat model.Methods Thirty?six male Wistar rats,weighing 250?300 g,were used and assigned into 4 groups according to random number ta?ble method,9 rats in each group.The groups included the normal control group,the model group,the low?dose catalpol group and the high?dose catalpol group.Except for the rats in normal control group,the rats in other groups were prepared by injection of Aβ25?35 in the right ventricle and D?galactose intraperitoneally.The low?dose catapol group was injected with 5 mg·kg^-1·d^-1 of cata?pol,and the high?dose catalpol group was injected with 10 mg·kg^-1·d^-1 of catapol.The normal control group and the model group were injected with the same volume of 0.9%sodium chloride solution intraperitoneally once a day for 7 days.Study index of rats was observed by Y?maze test,cortex structure of AD rats observed by Hematoxylin?ehong(HE)staining and electronic microscope,expression of M1 subtype of muscarinic cholinergic receptors(M1 receptor)in cerebral cortex observed by immunohistochemical staining,and protein content of M1 receptor detected by Western Blot.Results A rat in the model group died during the study and there were 8 rats left in the group while there were 9 rats in each of the other groups.Compared with the model group,the study in?dex of the rats increased significantly from the 14d(day 14:as for low?dose catalpol group t=3.267,P=0.030 9,as for high?dose catalpol group t=4.648,P=0.009 7;day 21:as for low?dose catalpol group t=5.010,P=0.007 4,as for high?dose catalpol group t=4.614,P=0.009 9).At day 14,the study indexes of rats in the 4 groups were(5.6±0.2),(2.6±0.3),(3.7±0.5),(4.4±0.6)re?spectively,and the study indexes turned to(6.3±0.8),(4.1±0.5),(5.3±0.4),(5.8±0.8)respectively at day 21.Abnormalities were found in cortex structure by HE staining,and ultrastructure changes of mitochondria,rough endoplasmic reticulum,nuclear chroma?tin were observed by transmission electron microscope,while the structure of the neuron was significantly improved in catalpol groups.Immunohistochemical staining results showed that the expression of M1 receptor in the cerebral cortex of rats decreased,the number of neurons decreased,and the expression of M1 receptor protein was down?regulated.Catalpol could increase the expression of M1 receptor protein significantly(compared with the model group,catalpol low dose group t=3.983,P=0.016 4 in the low?dose catalpol group;t=6.694,P=0.002 6 in the high?dose catalpol group).The expressions of M1 receptor protein in rats from 4 groups were 100%,64.75%,74.63%,and 85.74%respectively.Conclusion Catalpol could improve the abnormal structure of cerebral cor?tex in AD rats and increase the expression of M1 receptor.