B族维生素对大鼠糖尿病神经病理性痛的效应

Effect of B-vitamins （B1,B6,B12）on diabetic neuropathic pain in rats

目的 探讨B族维生素（维生素B1、B6、B12）对大鼠糖尿病神经病理性痛（DNP）的效应.方法 雄性SD大鼠104只,体重200～230 g,随机分为13组（n=8）：正常对照组（C组）,DNP组,DNP＋生理盐水组（NS组）,DNP＋维生素B110、33、100 mg/kg组（B1 10组、B133组、B1100组）,DNP＋维生素B610、33、100 mg,kg组（B610组、B633组、B6100）组）,DNP＋维生素B120.5、1.5、4.5 mg/kg组（B120.5组、B12 1.5组、B124.5组）,DNP＋维生素B1 10/B6 33/B12 1.5 mg,kg组（VBC组）.除C组外,其余各组均采用腹腔注射链唑霉素75 mg/kg 的方法制备DNP模型,于注射链唑霉素前2 d、注射后14 d时测定机械缩足阈值（MWT）和热缩足潜伏期（TWL）,MWT和TWL均低于基础值的85%为DNP模型制备成功.注射链唑霉素后14 d时腹腔注射相应剂量和种类的B族维生素或生理盐水,1次/d,连续2周,并于B族维生寨给药1、3、7、14 d时测定MWT和TWL,最后1次测定痛阈后处死大鼠,测定脊髓背角和背根神经节（DRG）磷酸化cAMP反应元件结合蛋白（p-CREB）的表达水平.结果 与C组相比,其余各组MWT降低,TWL缩短,脊髓背角和DRG p-CREB表达上调（P〈0.05）;与DNP组比较,各B族维生素组MWT升高,TWL延长,脊髓背角和DRG p-CREB表达下调,且呈剂量依赖性（P〈0.05）;与B110组、B633组、B121.5组比较,VBC组MWT升高,TWL延长,脊髓背角和DRG p-CREB表达下调（P〈0.05）.结论 B族维生素可减轻大鼠DNP,呈剂量依赖性,其机制可能与抑制脊髓背角和DRG CREB 的磷酸化有关.

Objective To evaluate the effect of B-vitamins（B1,B6,B12）on diabetic neuropathic pain （DNP）in rats.Methods 104 male SD rals weighing 200-230 g were randomly divided into 13 groups（n=8 each）：group Ⅰ control（group C）;group Ⅱ DNP;group Ⅲ DNP＋ normal saline（solvent of vitamins,group NS）;group Ⅳ,Ⅴ,Ⅵ DNP＋vitamin B1 10,33 or 100mg/kg,kg（group B1 10,group B133,group B1 100）;group Ⅶ,Ⅷ,Ⅺ DNP＋vitamin B6 10,33 or 100 mg/kg（group B6 10,group B633,group B6100）;group Ⅹ,Ⅲ,ⅫDNP＋vitamin B12 0.5,1.5 or 4.5 mg/kg （group B12 0.5,group B121.5,group B124.5）and group ⅩⅢ DNP＋vitamin B1 10/B6 33/B12 1.5 mg/kg（group VBC）.Diabetes was induced with intraperitoneal（IP） streptozocin mg/kg in group Ⅱ-ⅩⅢ.B-vitamins were give.IP once a day for 14 consecutive days starting from 14 d after IP streptozocin in group Ⅳ-ⅩⅢ.Venous blood samples were taken before（baseline）and 3 d after IP streptozocin for determination of blood glucose level. Successful induction of diabetes was defined as blood glucose 〉 14.6 mmol/L. Mechanical paw withdrawal threshold to yon Frey stimuli （MWT） and paw withdrawal latency to thermal nociceptive stimulus （TWL） were measured 2 days before and 14 days after IP streptozocin and on the 1, 3, 7, 14 days of B-vitamin administration. Animals with pain threshold measured at 14 days after IP streptozocin decreasing by less than 15% of the baseline were excluded from the study. The animals were sacrificed after the last pain threshold measurement and L4,5 lumbar segment of the spinal cord and dorsal root ganglions （DRG） were removed for determination of p-CREB expression using immuno-histuchemistry. Results MWT was significantly lower and TWL was significantly shorter and the expression of p-CREB was significantly higher in the other groups than in group C. B-vitamin administration significantly reduced thermal and mechanical hyperalgesia induced by diabetes and down-regulated the expression of p-CREB in a dose-dependent manner as compared with group DNP. The inhibitory effect of vitamin B complex against thermal and mechanical hyperalgesia was significantly stronger and the expression of p-CREB was significantly lower in group VBC as compared with group B110, group B633 and group B121 .5 respectively. Conclusion B-vitamains can attenuate DNP through inhibition of phospberylation of CREB in the spinal dorsal horn and DRG.