Effects Of Different Administration Routes Of Puerarin On Pain Threshold And Inflammatory Factors In Mice With Neuropathic Pain

Neuropathic pain(NP)is the pain which caused by primary damage and dysfunction of the nervous system.The pathogenesis is complicated,but there are no effective treatments in the clinic.Long-term chronic pain and torture seriously reduce the quality of life of patients,and cause a serious burden on society.Therefore,it is a hot research topic to explore the pathogenesis of NP and seek new therapeutic drugs.Puerarin,also known as puerarin,is an isoflavone derivative isolated from the root of Radix Puerariae.It has been found that puerarin can effectively inhibit the production of inflammatory factors and the activation of glial cells,and also alleviate multiple nerve damage and mechanical and thermal pain threshold of painful diabetic model mice.We can speculate that puerarin can effectively treat neuropathic pain from inhibiting inflammation levels of spinal cord.Objective:(1)To establish a mice neuropathic pain model and study the method of catheterization of lumbar subarachnoid space in a mice,to provide a reliable experimental basis for subsequent experiments;(2)To observe whether different administration methods of puerarin have therapeutic effects on neuropathic pain in mice,to provide experimental basis for clinical drug treatment of this disease;(3)To study whether the therapeutic effect of puerarin is related to the regulation of microglia transcription inhibitor sall1,to further provide the therapeutic mechanism of puerarin.Methods:(1)Establish a sciatic nerve branch selective injury(SNI)model by ligaturing and cutting the two branches of the left sciatic nerve of male BALB/c mice,the common peroneal nerve and the phrenic nerve,reserving the sural nerve.Von Frey cilia measures the changes in the 50% mechanical withdrawal threshold of mice before and after operation of SNI.IV(2)Puerarin is treated by intraperitoneal injection,intrathecal injection and intrathecal tube on the fifth day after SNI,The changes of mechanical pain threshold before and after administration are measured.(3)Detect the changes of IL-1?,IL-6 and TNF-? inflammation indexes using RT-qPCR in the spinal cord of SNI mice 7 days after operation and 7 days after administration.(4)Detect the changes of sall1 using RT-qPCR and Western-blot in SNI mice treated with puerarin for 7 days and 10 days.Results:(1)It can be seen that the five fingers are closed and flexed,and the mild valgus deformity after the operation of SNI mice.The mechanical pain threshold of the affected mice is significantly lower than that of the normal group and the sham operation group,The difference is statistically significant(P<0.05).(2)The mechanical pain threshold of SNI mice treated with intraperitoneal injection of puerarin dose not change significantly before and after administration(P>0.05).The mechanical pain threshold of mice after intrathecal injection and intrathecal tube administration is increased significantly compared with that before administration(P <0.05),It is proved that the two direct central administration methods of intrathecal injection and intrathecal catheter have therapeutic effects on SNI mice.(3)Results of RT-qPCR shows that the lever of IL-1?,IL-6 and TNF-? in the spinal cord of SNI mice are increased significantly after operation.The intracerebral injection of puerarin shows a higher level of inflammatory related indicators than that before administration.Inflammation-related indicators in spinal cord are significantly decreased after 7 days of administration of puerarin through the intrathecal catheter(P<0.05).(4)RT-qPCR and Western-blot results show that sall1 is decreased after operation of SNI,and decreased significantly at 7 days.mRNA and protein expression levels of sall1 are increased at 7 and 10 days after administration of puerarin from intrathecal catheter.The increase are most pronounced at 7 days and even increased to normal levels at 10 days.Conclusions:(1)The mechanical pain threshold of mice are decreased significantly after SNI model,The postoperative reduction of more than 40% compared with the preoperative baseline threshold is judged as successful modeling.Puerarin has no obvious effect on the treatment of pain-sensitive response in mice by intraperitoneal injection.Intrathecal injection and intrathecal tube have therapeutic effects on pain-sensitive response,indicating that puerarin is best absorbed by central administration,but intrathecal injection has further damage in the presence of inflammatory,the intrathecal tube is the safest and most effective method of administration.(2)The expression of sall1 in the spinal cord of mice is decreased after SNI model,and the decrease of sall1 is reversed after puerarin treatment,indicating that puerarin can treat neuropathic pain by reversing the decline of microglia transcriptional inhibitor sall1.