Wnt/?-Catenin Signal Pathway Involved In The Treatment Of Neuropathic Pain By Electroacupuncture

Objective:1.The CCI?Chronic constrictive injury?model was performed to evaluate the therapeutic effect of electroacupuncture?EA?in neuropathic pain?NP?;2.The expression of Wnt3a/?-catenin and the activation of astrocytes in L4-5 spinal cord of CCI rats were observed,so as to verify whether the Wnt/?-catenin signal pathway participate in activation of spinal astrocytes and elucidate the possible pathogenesis of NP.3.Moreover,observing the expression of Wnt3a/?-catenin and the activation of astrocytes after electroacupuncture treatment,so as to explore the possible mechanism of electroacupuncture treatment of NP.Methods:1.A total of 195 SD rats weighing 220²50g were selected as research subjects.According to the random number table method,rats were randomly divided into three groups,sham operation group?S group,n=65?,model group?M group,n=65?,and electroacupuncture group?D group,n=65?.2.M Group:the right sciatic nerve was isolated and ligated with 4-0 silk thread;In S group,only the right sciatic nerve trunk was isolated without ligation.In D group,based on CCI operation,two acupoints of"Huantiao"and"Weizhong"were stimulated with 2HZ/1mA electroacupuncture for 15min daily.3.The mechanical withdrawal threshold?MWT?and thermal withdrawal threshold?TWL?of the right foot in each group were measured at preoperative?T0?,postoperative 3days?T1?,postoperative 7 days?T2?,and postoperative 14 days?T3?respectively.The L4-5 spinal segments were removed after perfusion of normal saline into the heart,and the expressions of Wnt3a,?-catenin,GFAP and wnt3a mRNA and?-catenin mRNA in L4-5 tissues were detected by Western blot and qPCR.In addition,the expressions of IL-18in the L4-5 were detected by ELISA.5.Deep anesthesia was performed at the end of the behavioral test at T3,the chest was opened to expose the heart,perfused with 4%paraformaldehyde,and immunohistochemical assay were used to observe the activation of astrocytes.Results:1).MWT:rats in M group and D group were lower than those in group S at T₁?T₂?T₃?P<0.05?.At T₁?T₂?T₃,rats in D group were higher than M group?P<0.05?;TWL:rats in M group and D group were lower than those in group S at T₁?T₂?T₃?P<0.05?.At T₁?T₂?T₃,rats in D group were higher than M group?P<0.05?.2)IL-18 concentration in L4-5:the concentration of IL-18 in M group and D group began to increase at T₁,which was different from T₀?P<0.05?,at T₁?T₂?T₃,the concentration of IL-18 in M group and D group were significantly higher than that in group S?P<0.05?.The concentration of IL-18 in group D decreased at T₁?T₂?T₃,obviously lower than that in M group?P<0.05?.3).Expressions of wnt3a mRNA and?-catenin mRNA in L4-5 spinal cord tissues of rat in three groups:the expression of wnt3a mRNA and?-catenin mRNA in M group and D group began to increase at T₁,which was different from that of T0;Compared with S group,M group and D group increased at T₁?T₂?T₃?P<0.05?.At T₁?T₂?T₃,D group were significantly lower than group M?P<0.05?.4).The expressions of wnt3a and?-catenin in the L4-5spinal cord tissues of the three groups:the expression of wnt3a and?-catenin in the M group and the D group began to increase in T₁,which was different from that in T₀;Compared with group S,group M and group D increased at T₁?T₂?T₃?P<0.05?.At T₁?T₂?T₃,D group were significantly lower than M group?P<0.05?.5).The activation of astrocytes in L4-5 spinal cord tissues of the three groups:compared with the activation of astrocytes in S group,the expression of GFAP in group M and group D was significantly higher than that in group S at T₃?P<0.05?.The activation degree of astrocytes in group D was significantly lower than that in group M,and the expression of GFAP was significantly lower than that in group M?P<0.05?.Conclusion:1.CCI model induced the NP-associated hyperalgesia and prompted the activation of astrocytes and the release the proinflammtory cytokine IL-18 in spinal cord;2.Wnt/?-catenin signal pathway may mediate the activation of astrocytes thus promote the central sensitization of neuropathic pain;3.Electroacupuncture could inhibit the activation of Wnt/?-catenin pathway,thereby inhibiting the activation of astrocytes and blocking the further development of NP.