The Study Of The Effect Of Spinal Astrocytes On Chronic Pain Animal Models By Regulating IL-6

Objective:We observed the effect of spinal astrocytes in CFA-induced chronic inflammatory pain and the effect of spinal astrocytes on spinal nerve ligation(SNL)-induced neuropathic pain.Finally,we observed the effect of spinal IL-6 on SNL-induced neuropathic pain.Methods:1Rats were divided to 3 groups(n = 6 rats/group): CFA group(CFA was intraplantar injected into the hind-paw and saline was intrathecally injected at 6 d after operation),L-α-aminoadipate(LAA)group(CFA treatment with intrathecally administration of LAA),control group(normal rats).Mechanical allodynia and thermal hyperalgesia were tested before operation and 7 d after operation.The mRNA levels of spinal glial fibrillary acidic protein(GFAP)were tested 7d after operation.2Rats were divided to 4 groups(n = 6 rats/group): SNL group(spinal nerve ligation were ligated and saline was intrathecally injectedon 7 d after operation),sham group(SNL treatment except for spinal nerve ligation),L-α-aminoadipate(LAA)group(SNL treatment with intrathecal administration of LAA),control group(normal rats).Mechanical allodynia and thermal hyperalgesia were tested before operation and 7 d after operation.The mRNA levels of spinal GFAP were tested7 days after operation.3Spinal IL-6 was tested by enzyme-linked immunosorbent assay(ELISA)after the rat models of SNL establishment.IL-6 and IL-6 neutralizing antibody were intrathecal administration.The paw withdrawal thermal latency(PWTL)of rats was tested.Results:1.No significant difference of paw withdrawal mechanical threshold(PWML)or paw withdrawal thermal latency(PWTL)were observed among groups before operation(P> 0.05).PWML and PWTL in CFA group were significantly reduced,and the mRNA levels of spinal GFAP were significantly enhanced compared with control group 7 d after operation(P< 0.01).Compared with CFA group 7 d after operation,PWML and PWTL in LAA group were significantly enhanced and the mRNA levels of spinal GFAP were decreased(P < 0.01);2.No significant difference of paw withdrawal mechanical threshold(PWML)or paw withdrawal thermal latency(PWTL)was observed among groups before operation(P> 0.05).Compared with control group,PWML,PWTL and spinal GFAP mRNA levels of rats in sham group were no significant changed 7 d after operation(P> 0.05).PWML and PWTL in SNL group were significantly reduced,and the mRNA levels of spinal GFAP were significantly enhanced compared with control group 7 d after operation(P< 0.05).Compared with SNL group 7 d after operation,PWML and PWTL in LAA group were significantly enhanced,and the mRNA levels of spinal GFAP were decreased(P< 0.05);3.The spinal expression of IL-6 was increased in 3 and 7 d(P <0.05).The PWTL of rats of sham group were not different compared with sham-saline group(P >0.05).Comparing with the sham-saline group and SNL-saline group,PWTL of rats of SNL-IL-6 group were decreased(P <0.05).The PWTL in sham-anti-IL-6 was not significantly different compared with sham-saline group(P >0.05).However,comparing with SNL-saline group,PWTL in SNL-anti-IL-6 group was increased(P <0.05).Conclusions:1Spinal astrocytes could exert an important effect on CFA-induced chronic inflammatory pain.2Spinal astrocytes could exert an important effect on spinal nerve ligation-induced neuropathic pain.3The expression of spinal IL-6 acts a nociceptive role on SNL rats.