Analgesia Experimental Study Of Intrathecal Injection Lidocaine On SNL Rats

Part I:partial sciatic nerve ligation rats pain threshold as well as SCN9a gene and glial cell expressionObjectiveTo observe partial sciatic nerve ligation(SNL) rats’pain threshold as well as rat dorsal root ganglion (DRG) SCN9a gene expression changes and spinal cord glial cell activation.Methods30female SD rats, weighing210～250g, were randomly divided into three groups:sham operation group (Sham group, n=6), normal group (N group, n=6)and model group (SNL group, n=18). N group were not treated, the sham group and SNL group did sciatic nerve L5ligation model. Three groups were tested rat left hind limb mechanical paw withdrawal threshold value (Mechanical for the Withdrawal Threshold MWT)1day before sugery,3,6,9,12,14d after sugery. N and Sham group rats were killed at14d,the SNL group each six rats were killed at8,10,14d, took the DRG and lumbar enlargement spinal cord tissue, detected the expression of DRG Nav1.7and spinal cord GFAP (astrocyte activation flag) and OX42(microglia activation flag) by RT-PCR and Western-Blot methods. ResultsThe SNL group rats left hind limb mechanical paw withdrawal reflex threshold decreased significantly at3～14d after sugery, the difference was statistically significant (P<0.05); transcription and protein levels of Navl.7in DRG were significantly higher at8d,10d,14d after modeled, the difference was statistically significant (P<0.05); the OX42transcription and expression in spinal cord was no significantly change at8d,10d,14d after modeled, the difference was not statistically significant (P>0.05);the GFAP transcription and expression in spinal cord was significantly higher at8d,10d,14d after, modeled, the difference was statistically significant (P<0.05).ConclusionThe Nav1.7and spinal cord glial cells involved in the occurrence and development of rats SNL, microglia involved in the occurrence of SNL, astrocytes involved in the development of SNL. Part Ⅱ:Effects of intrathecal lidocaine of pain thresholds SCN9a gene expression and glial cells activation on the model of partial sciatic nerve ligationObjectiveObserved effects of intrathecal lidocaine of pain threshold、SCN9a gene expression and glial cells activation on the model of partial sciatic nerve ligation.Methods24female SD rats, weighing210-250g, were randomly divided into2groups: SNL model+intrathecal catheter+NS (NS group, n=6), the SNL model+intrathecal catheter+lidocaine group (Drug group, n=18). NS group, intrathecal inject25μl saline at the7th days, the Drug group,intrathecal inject2%lidocaine25μl. Measured the left hind limb mechanical paw withdrawal threshold MWT at8d,9d,10d,11d,12d,13d,14d after sugery.NS Group6rats were killed at14d; Drug group each6rats were killed at8,10,14d.Took the DRG and lumbar enlargement spinal cord tissue, detected the expression of DRG Nav1.7and spinal cord GFAP (astrocyte activation flag) by RT-PCR and Western-Blot and immunohistochemical methods.ResultsCompared with NS group,Intrathecal inject lidocaine7days after sugery could effectively enhanced SNL pain threshold, the difference was statistically significant (P<0.05),and the antinociceptive effects last4days after administration. Compared with NS group, transcription and expression of Nav1.7, GFAP in the Drug group were significantly lower at1d,3d after the administration of lidocaine, the difference was statistically significant (P<0.05)。ConclusionIn the middle of the selective sciatic nerve ligation in rats, a single intrathecal injection of lidocaine can reduce the Nav1.7expression in the rat dorsal root ganglion and reverse the activation of astrocytes, and significantly increasethe pain threshold in SNL rats.