Galanin and its receptor system promote the repair of injured sciatic nerves in diabetic rats

Various studies have reported that galanin can promote axonal regeneration of dorsal root ganglion neurons in vitro and inhibit neuropathic pain. However, little is known about its effects on diabetic peripheral neuropathy, and in vivo experimental data are lacking. We hypothesized that repeated applications of exogenous galanin over an extended time frame may also repair nerve damage in diabetic peripheral neuropathy, and relieve pain in vivo. We found that neuropathic pain occurred in streptozotocin-induced diabetic rats and was more severe after sciatic nerve pinch injury at 14 and 28 days than in diabetic sham-operated rats. Treatment with exogenous galanin alleviated the neuropathic pain and promoted sciatic nerve regeneration more effectively in diabetic rats than in non-diabetic rats after sciatic nerve pinch injury. This was accompanied by changes in the levels of endogenous galanin, and its receptors galanin receptor 1 and galanin receptor 2 in the dorsal root ganglia and the spinal dorsal horn when compared with nerve pinch normal rats. Our results show that application of exogenous galanin daily for 28 days can promote the regeneration of injured sciatic nerves, and alleviate neuropathic pain in diabetic rats.

慢病毒介导的DREAM沉默治疗在坐骨神经慢性压迫模型大鼠疼痛中的作用及其对GALR1的表达调控

目的甘丙肽受体1(galanin receptor 1,GALR1)信号通路在痛觉调节中发挥重要作用,该研究利用坐骨神经慢性压迫(chronic constriction injury of the sciatic nerve,CCI)大鼠模型,探索慢病毒介导的DREAM沉默治疗在CCI模型大鼠疼痛中的作用及其对GALR1的表达调控。方法选择健康雄性SD大鼠24只,随机分为4组(n=6):即RNA干扰组、空白载体组、单纯CCI组和正常对照组。鞘内置管前后分别测定基础痛阈,RNA干扰组和空白载体组于CCI后经微导管给予pKCSHR-Puro/GFP-DREAM慢病毒和空白载体,并测定腰段脊髓内下游调控元件拮抗分子(downstream regulatory element antagonist,DREAM)和GALR1的蛋白表达。结果大鼠痛阈的变化:手术同侧热痛阈和机械痛阈测定结果表明,CCI处理后,RNA干扰组、空白载体组及单纯CCI组在各个时间点热痛阈和机械痛阈较正常对照组均显著降低(P<0.01);RNA干扰组鞘内注射后较注射前痛阈显著升高,治疗后相同时间点RNA干扰组较空白载体组及单纯CCI组痛阈亦显著升高。Western blotting结果表明,与其他实验组对比,RNA干扰组的DREAM蛋白表达水平显著下调,而GALR1蛋白表达水平较空白载体组、单纯CCI组亦有显著下调。结论 DREAM可以调控GALR1的表达,提示甘丙肽受体1信号通路参与DREAM基因调节大鼠神经病理性疼痛。