| ObjectiveIn this study,On the basis of establishing the model of chronic cerebral ischemia mice,Morris water maze was used to analyze the effect of bilateral sciatica nerve stimulation on learning and memory ability in rats.HE staining was used to observe the pathological changes of neuronal cells in the hippocampal region of rat brain,TUNEL fluorescence staining was used to observe the apoptosis of neurons in the cerebral cortex,and the level of peripheral serum irisin was analyzed by ELISA.Finally,the levels of FNDC5(Fibronectin Type Ⅱ Domain Containing Protein 5),Irisin and brainderived neurotrophic factor(BDNF)in the hippocampus region of the brain were observed by immunohistochemistry,and the expression of PGC-1α(peroxisome proliferator-activated receptor-γ coactivator-1α)and FNDC5 proteins and genes in biceps femoris was analyzed from the protein and gene levels.In order to explore the possible mechanism of chronic cerebral ischemia leading to cognitive dysfunction and the possible mechanism of action of sciatic nerve electrical stimulation to improve learning and memory ability in rats with chronic cerebral ischemic cognitive dysfunction.These provides new ideas for the rehabilitation of chronic cerebral ischemia cognitive dysfunction in clinical practice.Methods24 male SD mice were randomly divided into three groups,sham group,model group and electrical stimulation group,8 in each group.Before surgery,the Morris water maze was used to test the learning and memory ability of all rats,including escape latency,number of platform crossing and target quadrant time,and after determining that there was no difference in learning and memory ability of all rats in the three groups.The chronic cerebral ischemic model was established by 2-vessel occlusion method in the model group and electrical stimulation group.4 weeks after surgery,Morris water maze was used to detect the escape latency,times of platform crossing and target quadrant time of rats in each group.After Morris water maze experiment,the rats in the electrical stimulation group were stimulated by sciatic nerve electrical stimulation,and the density wave with current of 1mA and frequency of 2/20 Hz was output(adjusted appropriately with slight muscle tremor without screaming and struggling in rats),which was stimulated daily for 20 minutes for 4 weeks.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.After the behavioral experiment,HE staining was used to observe the morphological changes of neurons in the hippocampal region of rats’brain,and TUNEL fluorescence staining was used to observe the apoptosis of neurons in the cerebral cortex of rats’ brain.Changes in the level of Irisin in peripheral serum are detected with ELISA.The expression of FNDC5,Irisin and BDNF in the hippocampus was detected by immunohistochemistry,and the average optical density was calculated and compared between groups,and the expression of PGC-1α,FNDC5 protein and mRNA in brain tissue and biceps femoris was detected by Western blot and RT-PCR.Results1)The results of Morris water maze experimental:Before modeling,there was no significant difference in escape latency,times of platform crossing and target quadrant time between the three groups(P>0.05).Before intervention,the escape latency of rats in the model group and the electrical stimulation group was longer than those in sham group.The times of platform crossing was significantly fewer,and the target quadrant time was shorter than those in sham group(P<0.05),while the difference between the model group and the electrical stimulation group were not statistically significant(P>0.05).After 4 weeks’ intervention,compared with the model group at the same time point and before intervention,the rats in the electrical stimulation group shortened their escape latency,increased the times of crossing platform and prolonged the target quadrant time,and the difference was statistically significant(P<0.05).Compared with the sham group at the same time point,the escape latency was prolonged,the times of crossing the platform was reduced,and the target quadrant time was shortened,the difference was statistically significant(P<0.05).2)The HE staining results of the hippocampal region of the brain:the neuronal cells in the hippocampal region of the rats in the sham group were relatively full,the cell membrane was intact,and the cytoplasmic staining was uniform,and the nucleus morphology was clear,and the neuronal cells were closely arranged and clearly hierarchical.In the hippocampal region of rats in the model group,a large number of neuronal cells collapsed,and the cell morphology changed significantly,and the demarcation between the nucleus and the cytoplasm was not clear,and the arrangement of neuronal cells was loose,and the number of cell layers was small,and the cell level was disordered.Compared with the sham group,a small number of damaged neuronal cells and large intercellular spaces were still visible in the electrical stimulation group.Compared with the model group,the number of damaged neuronal cells was significantly reduced,the number of cell layers was relatively increased,and the arrangement was more neat.These were concluded that the degree of neuronal cell damage in the hippocampal region of rats in the model group was significantly worse than that in the sham group,while compared with the model group,the number of normal neuronal cells in the hippocampal region of rats in the electrical stimulation group was significantly increased,and the degree of cell damage was significantly reduced.3)TUNEL fluorescence staining results of neurons in the cerebral cortex of the brain:TUNEL fluorescence staining was used to detect apoptosis of neurons in the cerebral cortex of rats’ brain,and the apoptostic neuronal cells were positive cells.The percentage of TUNEL-positive cells in the cerebral cortex of the model group was significantly higher than that in the sham group and the electrical stimulation group(P<0.05).The percentage of TUNEL-positive cells in the cerebral cortex in the electrical stimulation group was significantly higher than that in the sham group(P<0.05).4)The level of Irisin in serum:ELISA method was used to detect the level of Irisin in serum,and it was found that the level of Irisin in the model group was significantly lower than those in the sham group and the electrical stimulation group(P<0.05).The level of Irisin in the electrical stimulation group was lower than those in the sham group(P<0.05).5)Immunohistochemical results of FNDC5,Irisin,and BDNF in the hippocampus of the brain:the expressions of FNDC5,Irisin,and BDNF in the hippocampus of the rats in the model group were lower than those in the sham group,and the difference was statistically significant(P<0.05).The expressions of FNDC5,Irisin,and BDNF in the electrical stimulation group were significantly lower than those in the sham group(P<0.05).But higher than those in the model group,and the difference was statistically significant(P<0.05).6)The results of PGC-1α and FNDC5 protein expression in biceps femoris:the expression of PGC-1α and FNDC5 protein in the model group was significantly lower than those in the sham group(P<0.05),the expressions of PGC-1α and FNDC5 proteins in the electrical stimulation group were significantly decreased when compared with the sham operation group(P<0.05),and the expressions of PGC-1α and FNDC5 proteins in the stimulation group were more higher than those in the model group(P<0.05).7)The results of PGC-1α and FNDC5 mRNA expression in biceps femoris:the expression of PGC-1α and FNDC5 mRNA in the model group was significantly lower than those in the sham group(P<0.05),the expressions of PGC-la and FNDC5 mRNA in the electrical stimulation group were significantly decreased when compared with the sham operation group(P<0.05),and the expressions of PGC-1α and FNDC5 mRNA in the stimulation group were higher than those in the model group(P<0.05).Conclusion1.Cognitive dysfunction in rats caused by chronic cerebral ischemia may be related to the down-regulation of PGC-1α/FNDC5(Irisin)expression,the decrease of Irisin level in the hippocampus and the decrease of BDNF expression in the brain.2.Sciatic nerve electrical stimulation can promote the repair of damaged brain neurons,reduce the apoptosis of neuronal cells,and improve the learning and memory ability of rats with chronic cerebral ischemia.Its possible mechanism is to increase the expression level of BDNF in brain tissue by upregulating the expression of PGC1α/FNDC5(Irisin)pathway in brain and skeletal muscle. |
PDF Full Text Request