| Objective:Postoperative cognitive dysfunction(POCD) is one of most commonly complications of the central nervous system after anaesthesia. Previous studies showed that EA could ameliorate cognitive impairment associated with cerebral ischemia-reperfusion injury and Alzheimer’s disease. However, the effects of EA pretreatment on POCD in old patients are largely unknown. Apoptosis is the physiological process that removes superfluous and damaged neurons during nervous system maturation. However, the triggering of unregulated apoptosis has been implicated in the development of several neurodegenerative diseases and stroke. Neuron apoptosis pathway includes membrane receptor pathway, endoplasmic reticulum stress pathway and mitochondrial apoptosis pathway and so on. However, whether Mitochondrial apoptosis pathway play a role on the development of POCD and take part in the neuroprotection of EA pretreatment on old brain is still not well understood. Based on these findings and questions, the present study was undertaken to investigate the effects of electroacupuncture preconditioning on apoptosis of hippocampal neuron in cognitive dysfunctional rats, in order to definite the mechanism of EA pretreatment to reduce cognitive dysfunction, and provide reference for clinical.Methods:One hundred and fifty healthy male Sprague-Dawley rats, aged 18~20 months, weighing 550~600 g, were randomly divided into 3 groups(n=50 each) using a random number table:control group(group C), sevoflurane group(group S) and electroacupuncture preconditioning group(group EA).Animals inhaled pure oxygen for 4 h in group C, Electroacupuncture of Baihui, Dazhui and Zusanli acupoints lasting for 30 min was performed once a day for 5 consecutive days starting from 5 days before sevoflurane anaesthesia in group EA. Each acupiont was electrically stimulated with 1 m A(frequeney of sparse wave 2 Hz,frequeney of dense wave 15 Hz). Rats inhaled 3% sevoflurane for 4 h in S and EA groups at 24 h after preconditioning. 10 rats in each group were randomly selected, blood samples were taken immediately after the end of sevoflurane anesthesia for blood gas analysis.10 rats in each group were randomly selected,the cognitive function was assessed by Morris water maze 1 d after the end of anesthesia for 5 consecutive days. Ten rats were chosen at 1 and 6 days after anesthesia and hippocampal tissues were obtained for detection of cell apoptosis and mitochondrial membrane potential(MMP)(using flow cytometry) and expression of cytochrome c(Cyt c) in cytoplasm and activated caspase-3 in hippocampal neurons(by Western blot). The ultrastructure of hippocampal neuronal(mitochondria, endoplasmic reticulum, golgi apparatus, cytoplasm and nucleus) was observed with transmission electron microscope.Results: There were no significant differences in the parameters of blood gas analysis between the three groups(P>0.05).Compared with group C, the escape latency was significantly prolonged, the frequency of crossing the original platform, the percentage of time of staying at the original platform quadrant and MMP were decreased, the apoptotic rate was increased, and the expression of activated caspase-3 and Cyt c in cytoplasm was up-regulated in S and EA groups(P<0.05).Compared with group S, the escape latency was significantly shortened, the frequency of crossing the original platform, the percentage of time of staying at the original platform quadrant and MMP were increased, the apoptotic rate was decreased, and the expression of activated caspase-3 and Cyt c in cytoplasm was down-regulated in group EA(P<0.05).Microscopic examination showed normal hippocampal neuronal in group C; microscopic examination showed cytoplasm were severe edema,the inner and outer membranes of mitochondria were fusion and disappear, rough endoplasmic reticulum degranulation at 1 day after anesthesia in group S;cytoplasmic edema was lighten,most of the mitochondria still showed vacuoles, the golgi apparatus and rough endoplasmic reticulum abnormalities at 6th day after anesthesia in group S. microscopic examination showed cytoplasmic lighter edema,mitochondria showed vacuoles,the rough endoplasmic reticulum mildly abnormal,no expansion and degranulation at 1st day after anesthesia,vacuolization of mitochondria significantly reduced, The rough endoplasmic reticulum structure near normal at 6th day after operation in group EA.Conclusion:1 Electroacupuncture preconditioning of Baihui, Dazhui and Zusanli acupoints can alleviate POCD induced by sevoflurane anaesthesia in aged rats.2 The mechanism by which EA pretreatment-alleviated POCD induced by sevoflurane anaesthesia is related to the inhibition of mitochondria-mediated apoptosis in hippocampal neurons in aged rats. |
PDF Full Text Request