鞘内注射IRF8反义寡核苷酸对CCI模型大鼠痛阈的影响

EFFECTS OF INTRATHECAL INJECTION OF IRF8 ANTISENSE OLIGODEOXYNUCLEOTIDE ON PAIN THRESHOLDS IN RAT MODEL OF CHRONIC CONSTRICTION INJURY

目的:探讨鞘内注射小胶质细胞干扰素调节因子8(interferon regulatory factor 8,IRF8)反义寡核苷酸(oligodeoxynucleotide,ODN)对大鼠慢性坐骨神经缩窄损伤(chronic constriction injury of sciatic nerve,CCI)模型疼痛行为的影响。方法:雄性SD大鼠40只随机分为4组:Sham组、AS组、MM组、NS组,每组10只。除Sham组外,其他三组均鞘内置管并制备CCI模型,AS组、MM组、NS组依次于CCI后12 h鞘内注射IRF8反义/错义ODN、等体积生理盐水,1次/d,连续6 d。制模前测量各组大鼠的基础阈值,制模后1、3、5、7、10、12、14 d对大鼠进行疼痛行为测定。制模后7、14 d western blot检测IRF8、离子钙接合蛋白Iba1表达。结果:与Sham组比较,NS组、MM组大鼠神经损伤后右后爪机械痛阈和热痛阈均显著降低(P<0.05),脊髓IRF8、Iba1蛋白表达显著增强(P<0.05)。AS组于CCI后第10 d起右足机械痛阈和热痛阈下降,但仍高于MM组、NS组(P<0.05)。CCI后第7、14 d IRF8、Iba1蛋白表达,AS组较MM组、NS组显著减弱(P<0.05),但仍强于Sham组(P<0.05)。AS组第14 d IRF8、Iba1蛋白表达较第7 d增强(P<0.05)。结论:经鞘内注射IRF8反义寡核苷酸可抑制脊髓内IRF8表达和小胶质细胞活化而缓解CCI大鼠神经病理性疼痛。

Objective： To investigate the effects of intrathecal injection of interferon regulatory factor 8 （IRF8） antisense oligodeoxynucleotide （ODN） on neuropathic pain behaviors of rats with chronic constriction injury of sciatic nerve （CCI）. Methods： 40 adult male Sprague-Dawley rats were randomly assigned into four groups as follows （n = 10 in each group）： Sham group, AS group, MM group and NS group. All rats except Sham group successfully received intrathecal catheter implantation and chronic constriction injury of sciatic nerve. The rats in AS group, MM group and NS group were intrathecally treated with antisense ODN of IRF8, mismatch ODN of IRF8 or equivalent volume saline once daily for 6 days, since 12 hours after nerve injury. Basal pain thresholds were measured pre-operation, and pain behavioral changes were tested on 1 st, 3rd, 5th, 7th, 10th, 12th, 14th postoperative day, respectively. The expression oflRF8 and Ibal protein were measured in spinal cords on 7th, 14th postoperative day by using western blot. Results： The mechanical withdrawal threshold （MWT） and thermal withdrawal latency （TWL） on the ipsilateral hindpaw at all time points after nerve injury were significantly decreased （P 〈 0.05）, whereas the expression of IRF8 and Ibal protein in spinal cords were significantly increased （P 〈 0.05） in MM group and NS group than those in Sham group. The withdrawal thresholds in AS group were significantly lower than those in Sham group from 10th day after CCI （P 〈 0.05）, but still higher than those in MM and NS group. The expression of IRF8 and Ibal protein on day 7, 14 after CCI in AS group were significantly weaker than those in MM and NS group （P 〈 0.05）, but still stronger than those in Sham group （P 〈 0.05）. IRF8 and Ibal protein levels on day 14 were significantly upregulated comparing with those on day 7 in AS group （P 〈 0.05）. Conclusions： The neuropathic pain induced by CCI could be attenuated by intrathecal administration of IRF8 antisense ODN to inhibit IRF8 expression and microglia activation in the spinal cord.