The Effects Of NF-κB To The Rat Model Of CFA-induced Inflammatory Pain And The Expression Of Proinflammatory Cytokines Of The Spinal Cord

Objective To study the effect of intrathecal injection of pyrrolidine dithiocarbamate(PDTC),which is the inhibitor of NF-κB on rat model of CFA-induced inflammatory pain.The change of microglial cells and astrocytes,as well as the expression of the FKN receptor CX3CR1mRNA in glial cells were detected by immunohistochemistry and RT-PCR. PDTC is a 02specific inhibitor of NF-κB.We tried to give specific blocker of PDTC,when the signal pathway is blocked and the expression and activity of NF-κB is regulated,if the expression of CX3CR1 is blocked,then NF-κB pathway is an important signal systems to regulate FKN/CX3CR1.In addition,PDTC can be a new treatment of pain also.Methods 48 SD rats were randomly divided into 4 groups(n=12):(1) sham group(n = 12);without prior intrathecal injection of any drugs(2) intrathecal injection of PDTC + inflammatory pain group;this group rats were given intrathecal injection of PDTC(1000Pmol,once every day) 30min before hypodermic injection of CFA ankle joint(3) inflammatory pain +intrathecal PDTC group;this group rats were given intrathecal injection of 1000Pmol PDTC 30min after hypodermic injection of CFA at ankle joint(4) inflammatory pain group;this group rats were given hypodermic injection of CFA at ankle joint,but no PDTC.All groups were insterted a microapinal catheter intrathecally into the lumbar region according to the method of improved Yaksh,5 days later,the rats were injected complete Freund's adjuvant(CFA) at the left ankle joint,the second group,intrathecal injection of PDTC + inflammatory pain group were given intrathecal injection of PDTC(1000Pmol,once every day) 30min before hypodermic injection of CFA at outer side of ankle joint; the third group,inflammatory pain +intrathecal PDTC group were given intrathecal injection of 1000Pmol PDTC 30min after hypodermic injection of CFA at ankle joint;the first group,sham group didn't inject any reagents.Each injection capacity is 10 ml,and then washed the tubes with 10 ml normal saline.All drugs are dissolved and diluted by normal saline.The measurement of the pain-related behavior were measured by calculating the total reaction time of the pain behavior of rats' injected foot(injected foot's self- fat reduction,foot licking and biting).The rats sacrificed after the third day.The expressions of glial cell were observed by immunohistochemical method.The rats were then divided into 4 groups:sacrificed after the first day,the third day,fifth and seventh.Moreover,the expressions of CX3CR1mRNA,TNF-αmRNA and of L5 spinal cord segment of the rats were measured by RT-PCR method.Results①Compare the second group with the third group,Intrathecal injection of PDTC in advance can reduce the total response time to the pain behaviors of the injected foot of the adjuvant arthritis rats;compared with the sham group,there is a significant difference(P＜0.05),the rest of the treatment group had no impact on it.②compare with inflammatory pain group(group 4),intrathecal injection of PDTC + inflammatory pain group(group 2) and intrathecal injection of PDTC + inflammatory pain group(group 3),the number of immunoreactive cells of microglia cells in rats' spinal cord decreased significantly,there is a significant differences (P＜0.05).Moreover the expressions of CX3CR1mRNA and TNF-αmRNA of L5 segment of spinal cord of rats reduced apparently,there is significant differences as well(P＜0.05). Conclusion①intrathecal injection of PDTC in advance or injection of PDTC in the case of hyperalgesia existence can cause some antinociceptic effect to the adjuvant arthritis model rats②intrathecal injection of PDTC can inhibit the activation of microglial cells of the spinal cord,so that reducing the release of inflammatory factors,thus weakening the thermal hyperalgesia of the(complete Freund's adjuvant) CFA-induced arthritis pain models and have some analgesic effect.③In the CFA-induced arthritis model,the expressions of CX3CR1mRNA of spinal cord,NF-κB mRNA and TNF-αmRNA was significantly increased and there was a positive correlation,blocking NF-κB could reduce the expression of CX3CR1 mRNA and TNF-αmRNA.So we think the NF-κB pathway may be the middle link of the pain signal transmission, meanwhile,indicating that the NF-κB signaling pathway may be one of the mechanisms of the formation and maintenance of inflammatory pain.