Effects Of Sciatic Nerve Electrical Stimulation On Expression Of Vascular Endothelial Growth Factor In Hippocampus And Learning And Memory Function Of Rats With Chronic Cerebral Hypoperfusion

Objective The study observed the effect of sciatic nerve electrical stimulation on learning and memory function of rats with chronic cerebral hypoperfusion(CCH),and explored the expression of vascular endothelial growth factor(VEGF)in hippocampus to analyze the possible mechanism,in order to provide a new idea for the treatment of cognitive dysfunction in clinic.MethodsThirty two rats were randomly divided into four groups by random number table method:normal group,sham operation group,model group and stimulation group,with 8 rats in each group.Morris water maze was used to test the swimming speed and escape incubation period of all rats at first.After no difference was found,CCH model was established by modified 2-VO method in model group and stimulation group.4 weeks after modeling,Morris water maze was used to detect the escape incubation period,the times of crossing the platform and the residence time of the target quadrant of rats in each group.After the water maze experiment,the rats in the stimulation group were stimulated by sciatic nerve electrical stimulation,and the density wave with current of 1m A and frequency of 2/20 Hz was output(adjusted appropriately with slight muscle tremor without screaming and struggling in rats),which was stimulated for 20 minutes every day.After 4 weeks of intervention,Morris water maze test was performed again to observe the changes of learning and memory function before and after intervention.HE staining was used to observe the morphological changes of hippocampal cells in each group.Immunohistochemistry was used to detect the expression of neuron-specific enolase(NSE)and VEGF in hippocampal neurons.Finally,the average optical density(AOD)values were calculated and compared between groups.ResultsMorris water maze results showed that there was no significant difference in swimming speed and escape incubation period in each group before modeling(P>0.05).Before intervention,the escape incubation period of rats in model group and stimulation group was longer than those in normal group and sham operation group,and the times of crossing platform were fewer,and the time of target quadrant was shorter.The difference was statistically significant(P<0.05).There was no significant difference between normal group and sham operation group,model group and stimulation group(P>0.05).After 4weeks of intervention,compared with the model group at the same time point and before intervention,the rats in the stimulation group shortened their escape incubation period,increased the times of crossing platform and prolonged the time of target quadrant,with statistical significance(P<0.05).Compared with normal group and sham operation group at the same time point,their escape incubation period was longer,the times of crossing platform were fewer,and the target quadrant time was shorter,the difference was statistically significant(P<0.05).HE staining showed that the damage degree of hippocampal neurons in model group was more serious than that in normal group and sham operation group,while the number of normal neurons in stimulation group increased compared with that in model group,and the damage degree was reduced.Immunohistochemical results showed that there was no significant difference in the expression of NSE and VEGF in hippocampus between normal group and sham operation group(P>0.05).The expression of NSE and VEGF in hippocampus of model group was lower than that of normal group and sham operation group,the difference was statistically significant(P<0.05).The expression of NSE and VEGF in hippocampus of rats in stimulation group was higher than that in model group,and the difference was statistically significant(P<0.05).Compared with normal group and sham operation group,the expression in stimulation group decreased,but there was no significant difference(P>0.05).ConclusionElectrical stimulation of sciatic nerve can protect neurons in hippocampus of rats with CCH and improve learning and memory function.The possible mechanism is related to the increased expression of VEGF in hippocampus of rats.