慢性坐骨神经缩窄性损伤后大鼠脊髓背角神经节上BKca-α的表达变化

目的通过建立慢性坐骨神经缩窄性损伤模型(chronic constriction injury of the sciatic nerve model,CCI),观察神经病理性疼痛状态下大鼠脊髓背角神经节(dorsal root ganglion,DRG)神经元大电导的钙激活钾通道α亚基(largecalcium-activated potassium channel alpha subunits,BKca-α)的表达。方法雄性SD大鼠70只,体质量180～230g,分为空白对照组、假手术和手术组(CCI组)。CCI组于右后肢结扎坐骨神经制作CCI模型,假手术组仅做钝性分离,空白对照组不做任何处理。于术前及术后1、3、7、10、14、17、21d测定各组机械缩爪阈值和热缩足潜伏期(radiant heat stimulation,PWHL)。于术后7、14、21d采用RT-PCR和Western blot检测各组大鼠脊髓L4～L6段DRG上BKca-αmRNA和蛋白表达水平变化。结果①与空白对照组和假手术组比较,CCI组术后3～21d热痛阈和机械痛阈明显降低(P<0.01);空白对照组和假手术组间热痛阈和机械痛...

Decreased expression of large calcium-activated potassium channel α subunit in dorsal root ganglion neurons in rats of chronic constriction injury of the sciatic nerve

Objective To examine the changes in the plasticity of the large calcium-activated potassium channel α subunit (BKca-α) mRNA and protein in dorsal root ganglion (DRG) neurons and the role it plays in the chronic constriction injury of the sciatic nerve (CCI). Methods Seventy male SD rats weighing 180 to 230 g were randomly divided into 3 groups, control group, sham operation group and CCI group. The sciatic nerve of the right hind leg was exposed without any injury in sham group, but operated according to the methods of Bennett and Xie with slightly improvement in CCI group. Fifty percent paw withdraw thresholds (50% PWML) and radiant heat stimulation (PWTL) were measured before the surgery and in 1, 3, 7, 10, 14, 17 and 21 d later after sciatic nerve ligation. The DRG of the L_4 to L_6 segments of spinal cord were executed respectively in 7, 14 and 21 d after surgery and the expressed variation of the BKca-α mRNA and protein were detected by RT-PCR and Western blotting. Results PWTL and PWML were significantly decreased during the 7th to 21st day after CCI as compared to the baseline and sham group. There was no significant difference in BKca-α mRNA and protein expression between the control and sham groups. But the expression was markedly decreased in the surgery groups. Conclusion The down-regulation of the mRNA and protein expression of the BKca-α subunit in the DRG neurons may play an important role in neuropathic pain and spinal cord sensitiveness.