维生素C复合低剂量加巴喷丁对大鼠神经病理性痛的影响

Effects of vitamin C combined with low dose of gabapentin on neuropathic pain in rats

目的 评价维生素C复合低剂量加巴喷丁对大鼠神经病理性痛的影响.方法 SPF级雄性SD大鼠50只,体重225 ～ 275 g,6～7周龄,采用随机数字表法,将其分为5组（n=10）：假手术组（Sham组）、神经病理性痛组（NP组）、维生素C组（VitC组）、加巴喷丁组（Gap组）、维生素C复合加巴喷丁组（VitC＋ Gap组）.采用坐骨神经慢性结扎（CCI）法建立神经病理性痛模型.VitC组、Gap组和VitC＋ Gap组分别于建模后7d腹腔注射维生素C 500 mg/kg、加巴喷丁30 mg/kg、维生素C 500mg/kg和加巴喷丁30 mg/kg的混合液,连续7d,2次/d.所有药物生理盐水稀释至1ml,Sham组和NP组则腹腔注射生理盐水1ml.于建模前、建模后3、7和14 d时测定机械缩足阈（PWMT）和热缩足潜伏期（PWTL）.于建模后14 d,采集颈动脉血样6 ml,处死后取脊髓,采用硫代巴比妥酸法测定血清MDA浓度,RT-PCR法测定脊髓Slc23a2 mRNA表达水平.结果 与Sham组比较,NP组、VitC组、Gap组和VitC＋ Gap组左足PWMT和PWTL降低,NP组血清MDA浓度升高,脊髓Slc23a2 mRNA表达下调,VitC组和Gap组脊髓Slc23a2 mRNA表达下调（P＜0.05）,VitC＋ Gap组脊髓Slc23a2 mRNA表达差异无统计学意义（P＞0.05）.与NP组比较,VitC＋ Gap组建模后14 d时左足PWMT和PWTL升高,血清MDA浓度降低,脊髓Slc23a2 mRNA表达上调,VitC组血清MDA浓度降低（P＜0.05）,VitC组、Gap组左足PWMT和PWTL差异无统计学意义（P＞0.05）.各组各时点右足PWMT和PWTL差异无统计学意义（P＞0.05）.结论 维生素C复合低剂量加巴喷丁可以有效缓解神经病理性痛,其机制可能与两药物复合应用上调了Slc23a2 mRNA表达,增加维生素C转运入神经细胞,从而抑制氧化应激有关.

Objective To evaluate the effects of vitamin C combined with low dose of gabapentin on neuropathic pain （NP） in rats.Methods Fifty male Sprague-Dawley rats,weighing 225-275 g,aged 6-7 weeks,were randomly assigned into 5 groups （n =10 each）：sham operation group （group Sham）,NP group,vitamin C group （group VitC）,gabapentin group （group Gap）,and vitamin C combined with gabapentin group （VitC ＋ Gap group）.NP was induced by chronic constrictive injury in the rats anesthetized with pentobarbital sodium.The sciatic nerve was exposed and 4 silk ligatures were placed on the sciatic nerve at 1 mm intervals.In VitC,Gap and VitC＋ Gap groups,vitamin C 500 mg/kg,gabapentin 30 mg/kg,and vitamin C 500 mg/kg ＋ gabapentin 30 mg/kg diluted in normal saline 1 ml were injected intraperitoneally,respectively,twice a day for 7 consecutive days starting from 7 days after NP.Normal saline 1 ml was given in Sham and NP groups.Before NP and at 3,7,and 14 days after NP,the paw withdrawal threshold to mechanical stimuli （PWMT） and paw withdrawal latency to thermal stimuli （PWTL） were measured.At 14 days after NP,the blood samples were drawn from the carotid arteries.The rats were then sacrificed and the spinal cord was removed for determination of concentrations of malondialdehyde （MDA） in serum （by using Thiobarbituric acid method） and Slc23a2 mRNA expression （by RTPCR）.Results Compared with Sham group,PWMT and PWTL in left paws were significantly decreased in NP,VitC,Gap ard VitC ＋ Gap groups,the concentrations of MDA in serum were increased and Slc23a2 mRNA expression was down-regulated in NP group,Slc23a2 mRNA expression was down-regulated in VitC and Gap groups,and no significant change in Slc23a2 mRNA expression was found in VitC ＋ Gap group.Compared with NP group,PWMT and PWTL in left paws were significantly increased,the concentrations of MDA in serum were decreased,and Slc23a2 mRNA expression was up-regulated in VitC ＋ Gap group,the concentrations of MDA in serum were decreased in VitC group,and no significant changes were found in PWMT and PWTL in left paws in VitC and Gap groups.There were no significant differences in PWMT and PWTL in fight paws at each time point between the five groups.Conclusion Vitamin C combined with low dose of gabapentin can relieve NP effectively,and up-regulation of Slc23a2 mRNA expression,increased trafficking of vitamin C to neurons and inhibition of oxidative stress may be involved in the mechanism.