ABSTRACT
Objective:To explore how electrical stimulation of the sciatic nerve affects learning and memory in cases of chronic cerebral hypoperfusion and its mechanism.Methods:Thirty-two Sprague-Dawley rats were randomly divided into a normal group, a sham-operation group, a model group and a stimulation group, each of 8. In the model and stimulation groups a chronic cerebral hypoperfusion model was established using the modified 2-VO method. The stimulation group then received electrical stimulation of the sciatic nerve for 4 weeks. Afterward all of the rats′ learning and memory were tested using the Morris water maze. HE staining and immunohistochemistry were used to observe any morphological change in the hippocampus and the expression of neuron-specific enolase (NSE) and vascular endothelial growth factor (VEGF).Results:The model and stimulation groups demonstrated significantly longer escape latency, fewer platform crossing times and shorter target quadrant times than the normal and sham-ope-ration groups before the intervention. All of these indicators had improved after the intervention. According to the HE staining, neuronal damage in the hippocampus was aggravated significantly in the model group compared with the normal and sham-operation groups, while the degree of damage was reduced in the stimulation group. Moreover, the immunohistochemistry results suggested that the expressions of NSE and VEGF were reduced significantly in the model group compared with the normal and sham-operation groups, while in the stimulation group they had increased significantly compared with the model group.Conclusions:Electrical stimulation of the sciatic nerve can improve learning and memory in cases of chronic cerebral hypoperfusion, at least in rats. It is probably related to the increased expression of VEGF in the hippocampus.
ABSTRACT
Objectives @#To investigate the effect of sciatic nerve electrical stimulation ( SNES) on motor function recovery in rats with incomplete spinal cord injury (SCI) and its possible mechanism.@*Methods @#The incomplete SCI model was constructed by modified Allen ′s method. Forty⁃five Sprague⁃Dawley (SD) rats were randomly divided into three groups : Sham , SCI , and SNES. Electrical stimulation parameters were 1 ms pulse width and 100 Hz , with 20 mins each time , once a day for 21 days. The motor function was assessed by Basso⁃Beattie⁃Bresnahan (BBB) locomotor function scale , and the action potential conduction was detected by electrophysiology. Hematoxy⁃lin⁃eosin (HE) staining was used to observe the pathological changes in the spinal cord and the average cross⁃sectional area (CSA) of biceps femoris muscle fibers. The number of brain⁃derived neurotrophic factor (BDNF) and tropomyosin⁃related kinase B (TrkB) positive cells , relative mRNA and protein expression were analyzed by immunohistochemistry , reverse transcription polymerase chain reaction (RT PCR) and Western blot separately.@*Results@#On 21 d , the BBB score and average amplitude of action potential of SNES group were higher than those of SCI group , and the difference was statistically significant (P < 0. 05) . Compared with SCI group , the pathological injury of spinal cord tissue in SNES group was significantly improved , and the average CSA of biceps femoris muscles had a statistical difference (P < 0. 05) . The number of BDNF and TrkB positive cells in SNES group was higher than that in SCI group , and there were statistical differences (P < 0. 05) . The relative mRNA and protein expressions of BDNF and TrkB in SNES group were higher than those in SCI group , with statistical differences ( P <0. 05) . The relative mRNA and protein expressions of BDNF and TrkB in SNES group were higher than those in SCI group , with statistical differences ( P <0. 05) . @*Conclusion @#These results show that SNES contributes to alleviating spinal cord tissue injury , promoting the recovery of motor function and delaying the atrophy of muscles below the injury level. The possible mechanism is related to the increased expression of BDNF⁃TrkB proteins.