| Purpose:This experimental study aims to simulate chronic contractile injury(CCI)of the sciatic nerve in rats by ligating the sciatic nerve.And on the basis of this injury model,we are looking for evidence of the neuroprotective effect of erythropoietin(EPO)on the peripheral neuropathic injury of rats with chronic compression injury.Method:Forty-five healthy SD rats,weighing about 250g,were randomly divided into sham operation group,CCI group and CCI+EPO group,with 15 rats in each group.The sham operation group only exposed the sciatic nerve in the middle of the right thigh;the CCI group used 4-0 chromium intestinal suture material to ligate four ligatures around the nerve at 1-2 mm intervals,and injected subcutaneously with the same dose of saline as the treatment group;In the CCI+EPO group,3000 U/kg of recombinant human erythropoietin(rhu-EPO)was injected subcutaneously every day after ligating the nerve.And 1 day before the operation and 3,7,14 and 21 days after the operation,the mechanical injury threshold and thermal injury threshold were evaluated as behavioral assessment.Rats in each group were subjected to hematoxylin-eosin staining to identify the morphology of dorsal root ganglion cells on the 7th or 21st day after surgery,and the satellite glial cells(SGCs)were counted.On the 21st day after operation,all mice were compared by Western-blotting,and the expression of AMPK,p-AMPK,mTOR,p70S6K and AQP-2 protein in ganglion cells was analyzed.Results:General observation:After the rat model of chronic contractile injury of the sciatic nerve was established,the lower extremities of the CCI group and CCI+EPO group immediately experienced movement disorders such as claudication and weakness of toes extension.As time progressed,the two groups of rats began to gradually experience toe atrophy,nail loss,foot swelling and skin loss.No abnormal changes were observed in rats in the sham operation group.Paw Withdrawal latency test results:One day before surgery,there was no statistically significant comparison between PWT and PWL among the three groups of rats,P>0.05.Compared with 1 day before operation,PWT and PWL of CCI+EPO group and CCI group were shortened at 1 day after operation,P<0.05,the difference was statistically significant;PWT of CCI+EPO group was 7 days,14 days and 21 days after operation,PWL time is longer than CCI group,P<0.05,the difference is statistically significant.HE staining results:After the operation,compared with the CCI group,the neuronal cell edema of the CCI+EPO group was less,and the vacuole changes were less,but the EPO treatment did not completely restore the tissue to normal.Counting the number of astrocytes(SGCs)yielded similar results.The count of SGCs in CCI group was significantly higher than that in sham operation group,P>0.05.Compared with CCI group,CCI+EPO had a significant decrease in SGCs count,P>0.05.Western-blot test results:Western-blot test results:the expression of AQP-2 in the DRG tissue of the sham operation group was close to negative,the expression of AQP-2 in the control group and the treatment group after CCI treatment was significantly increased,while the EPO treatment group was compared with the CCI group The expression of AQP-2 decreased significantly,P>0.05.The treatment group was similar to the sham operation group,but there was still a significant increase,P>0.05.The expression of AMPK,p-AMPK,mTOR and p70S6K in the sham operation group was the lowest among the three groups,while the expression of AMPK,p-AMPK,mTOR and p70S6K in the CCI group was the highest among the three groups.At the same time,the EPO treatment group was compared with the CCI group The expression of AMPK,p-AMPK,mTOR and p70S6K decreased significantly,P>0.05.Conclusion:1.EPO is an effective therapy for PNI-related neuropathic pain in the CCI rat model;2.EPO can effectively protect the pathological damage of DRG in CCI model rats;3.EPO may influncen the expression of AQP-2 in DRG tissues of CCI model rats through AMPK/mTOR/p70S6K signaling pathway. |
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