To Explore The Mechanism Of Improving The Motor Function Of SNI Model Rats By Synaptic Plasticity

ObjectiveTo elucidate the mechanism of Chinese tuina treating sciatic nerve crush injury on synaptic plasticity by functional analysis and using molecular biological and immunohistochemical techniques to detect the levels of Synapsin Ⅰ, tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1(PAI-1), nAChR and its inducing factors before and after tuina treatment.MethodsAll Sprague-Dawley rats were devided into 5 groups including normal group(N), sham-operated group(S), model group(M), model control group(MC) and Tuina group(T).Rats from the last three groups were subjected to sciatic nerve crush injury. Rats from group S went through a sham operation. Group M and MC served as controls while group T received tuina therapy since day 7 post-surgery. The sciatic functional index (SFI) and BBB score were examined every 5 days during treatment session.Realtime PCR, western blot, immunohistochemistry and Elisa techniques were performed to detect the levels of Synapsin I,tPA, PAI-1, nAChR and its inducing factors before and after tuina treatment.Results1 Functional assessmentSFI:The SFI of the rats went through the surgery were significantly lower than that of group N (p<0.05), which suggested the success of the model. On the 5th day post-treatment, group T presented a recovering tendency compared with group M and MC(p>0.05). On day 10 post-treatment, scores of group T was significant higher than that of group M (p<0.05), and was still lower than that of group N. On day 20 post-treatment, group T showed significant improvement (p<0.05) compared with group M and MC, but it was still significantly lower than group N (p<0.05).And there was no difference between group N and T(p>0.05).BBB score:The scores of the rats went through the surgery were significantly lower than group N (p<0.05). On the 5th day post-treatment, group T presented a recovering tendency compared with group M and MC(p>0.05). On day 10,15 and 20 post-treatment, scores of group T was significant higher than that of group M and MC(p<0.05), and was lower than that of group N(p<0.05).2 Results of Synapsin I and p-Synapsin IComparing with group N, the gene transcription of Synapsin I and the expression of p-Synapsin I were declined significantly after surgery(p<0.05). On day 20 post-treatment, Synapsin I mRNA in group T was significantly higher than that in group M and MC(p<0.05), and higher than that in group N with no significant difference(p>0.05). The expression of p-Synapsin I was higher than that in group M and MC (p<0.05), and lower than that in group N(p<0.05).3 Results of tPA and PAI-1A significant increase (p<0.05) in tPA and PAI-1 was found in the sciatic nerve of rats subjected to sciatic nerve crush injury compared with group N. On the day 20 post-treatment, the expression of tPA in group M and MC presented a descending tendency but were significantly higher compared with that of group N(p< 0.05),however, the expression of PAI-1 revealed a ascending tendency and was significantly higher compared with that of group N(p<0.05). After 20 times tuina treatment,group T exhibited significant decreases (p<0.05) in tPA and PAI-1 when compared with that of group M and MC.4 Results of nAChR and its inducing factorsComparing with group N, a significant increase (p<0.05) in y-nAChR mRNA and decrease in s-nAChR mRNA was found induced by the surgery. On day 20 post-treatment, the gene transcription of y-nAChR in group M and MC maintained steady, otherwise ε-nAChR presented a rising tendency and was significantly higher than that of group N(p<0.05). The γ-nAChR in group T was lower than that in group M and MC(p<0.05). However,ε-nAChR of group T was significantly higher than that of group M and MC(p<0.05), and was approaching the value of group N.Comparing with group N, a significant decrease(p<0.05) in Agrin, MuSK mRNA and the concentration of MuSK was found on day 0 and 20 post-treatment. The gene transcription of Agrin and MuSK in group T were higher than that of group M and MC(p<0.05) and lower than that of group N (p< 0.05).The concentration of MuSK in group T was significantly higher than that of group N, M and MC (p< 0.05).Conclusions1 Tuina improved the motor function of sciatic nerve injured rats.2 Tuina upregulated the gene transcription of Synapsin Ⅰ and expression of p-Synapsin Ⅰ.This in turn accelerates the connection between motor neurons in the spinal cord and the target organs.3 Tuina downregulated the levels of tPA and PAI-1, accelerate the removal of fibrin deposition and prevent collagen scarformation. It helps pave a road for synaptic remodeling at the site of injury.4 Tuina enhancing the levels of inducing factors may in turn accelerate the γ-ε switch,improve reinnervation of denervated muscles, and raise the efficiency of synaptic transmission.