鞘内注射P300 siRNA对神经病理性痛大鼠的镇痛效果

目的 评价鞘内注射p300小干扰RNA(p300siRNA)对神经病理性痛大鼠的镇痛效果.方法 取鞘内置管成功的雄性SD大鼠96只,采用坐骨神经慢性压迫性损伤法(CCI)建立神经病理性痛模型,随机分为4组(n=24):假手术+生理盐水组(S组)、CCI+生理盐水组(CCI组)、CCI+转染试剂组(V组)和CCI+p300siRNA组(P组).于术后3～6 d时鞘内注射生理盐水、转染试剂或p300siRNA(siRNA 4μg溶于转染试剂)各20μl,2次/d,10μl/次,连续4 d.于术前1 d(基础状态)、术后1、3、5、7、9、11、14 d时测定机械痛阈和热痛阈;于术后3、7、14 d时取腰段脊髓,测定p300蛋白及其mRNA、乙酰化组蛋白H3(Ac-H3)的表达.结果 与基础值比较,CCI组、V组和P组术后各时点机械痛阈和热痛阈降低(P＜0.05).与S组比较,其余各组机械痛阈和热痛阈降低,p300蛋白及其mRNA和Ac-H3蛋白表达上调(P＜0.05).与CCI组比较,P组机械痛阈和热痛阈升高,p300蛋白及其mRNA和Ac-H3蛋白表达下调(P＜0.05).结论 鞘内注射p300 siRNA可减轻大鼠神经病理性痛,其机制与抑制脊髓p300和Ac-H3蛋白的表达有关.

Analgesic efficacy of intrathecal p300 siRNA in a rat model of neuropathic pain

Objective To investigate the analgesic efficacy of intrathecal p300 small interfering RNA (siRNA) in a rat model of neuropathic pain. Methods Ninety-six male SD rats in which intrathecal catheter was successfully placed were used in this study. Neuropathic pain was induced by chronic constrictive injury (CCI).Loosely constrictive ligatures were placed around the common sciatic nerve. The rats were randomly divided into 4 groups (n = 24 each): sham operation + normal saline (NS) group (group S), CCI + NS group (group CCI),CCI + transfection agent group (group Ⅴ) and CCI + p300 siRNA group (group P). Intrathecal NS 20 μl, transfection agent 20 μl or p300 siRNAs (in transfection agent) 20 μl was injected twice a day (10 μl every time) for 4consecutive days from 3 to 6 days after operation. Mechanical pain threshold and thermal pain threshold were measured at 1 day before operation (baseline) and at 1, 3, 5, 7, 9, 11, 14 days after operation. The animals were then killed and the lumbar segment of the spinal cord was removed at 3, 7 and 14 days after operation to detect the expression of p300 protein and mRNA and Ac-H3. Results Mechanical pain threshold and thermal pain threshold were significantly decreased at each time point after operation in group CCI, V and P compared with the baseline value (P ＜ 0.05). Mechanical pain threshold and thermal pain threshold were significantly decreased and the expression of p300 mRNA and protein and Ac-H3 was up-regulated in group CCI, V and P compared with group S (P ＜ 0.05). Mechanical pain threshold and thermal pain threshold were significantly increased, and the expression of p300 mRNA and protein and Ac-H3 was down-regulated in group P compared with group CCI (P ＜ 0.05).Conclusion Intrathecal p300 siRNA can attenuate the neuropathic pain in rats with CCI and the mechanism may be related to the inhibition of the expression of p300 and Ac-H3 in the spinal cord.