多巴胺能神经元对鱼藤酮敏感性的增龄改变及其机制

目的 研究鱼藤酮对不同月龄SD大鼠多巴胺能神经元的影响及其机制.方法 3、12、20月龄雄性SD大鼠各40只,按照随机数字表法分为自然增龄组和鱼藤酮处理组,每组20只.自然增龄组皮下注射无鱼藤酮的混合溶剂,处理组皮下注射鱼藤酮[1.0 mg/(kg·d)],连续给药30d,每周停药1d,构建大鼠鱼藤酮染毒模型.大鼠黑质切片采用酪氨酸羟化酶(TH)免疫组化染色；测定黑质组织匀浆超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性；Western blotting检测黑质部位caspase-3表达水平.结果 鱼藤酮处理后各月龄大鼠TH阳性细胞计数均比相应自然增龄组降低,且20月龄大鼠降低最为明显,差异均有统计学意义(P＜0.05).自然增龄组3月龄大鼠黑质组织SOD和CAT活性最高,20月龄大鼠有所下降,而鱼藤酮处理后各月龄大鼠SOD、CAT活性均明显增加,差异有统计学意义(P＜0.05).Western blotting结果显示,鱼藤酮处理组各月龄大鼠剪切活化的caspase-3的表达较自然增龄组均明显增加,差异有统计学意义(P＜0.05),其中20月龄大鼠最为明显.结论 鱼藤酮可诱导大鼠TH阳性细胞随年龄增加而减少,氧化应激水平的增高和caspase-3的激活可能参与了SD大鼠对鱼藤酮敏感性随年龄增加的作用机制.

Aging-related sensibility of dopaminergic neurons to rotenone

Objective To investigate the influence of rotenone neurotoxin on dopaminergic neurons from SD rats of different months and its mechanism.Methods Forty 3-month-old,4012-month-old and 40 20-month-old SD rats were chosen in our study and equally randomized into control group and rotenone treatment group,respectively(n=20); rotenone(1.0 mg/[kg·d])was given to the rats in the rotenone treatment group for 30 consecutive d(having drug withdrawal 1 d per week)to induce rotenone neurotoxin models.Tyrosine hydroxylase immunoreactivity in the substantia nigra pars compacta(SNpc)was observed.Levels of total superoxide dismutase(SOD)and catalase(CAT)were determined by colorimetric method and protein level of caspase-3 was determined by Western blotting.Results A significant decreased number of TH-positive cells in 3-,12-and 20-month-old rats of rotenone treatment group was noted as compared with that in the control group,respectively(P＜0.05),and 20-month-old rats had the fewest number.SOD and CAT activities in 3 month-old rats of the control group enjoyed the highest level and decreased trend was noted in 20 month-old rats of the control group;as compared with those in the control group,the SOD and CAT activities in all the rats of rotenone treatment group increased significantly(P＜0.05).Western blotting revealed that the expression of cleaved caspase-3 in all the rats of rotenone treatment group obviously increased as compared with those in the control group,and 20-month-old rats showed the highest level of active caspase-3.Conclusion Rotenone can induce the decrease of TH-positive cell level following the increase of rat age; increase levels ofcaspase-3 and oxidative stress may take part in the mechanism of high sensibility of old SD rats to rotenone.