大鼠脊髓背角HCN4通道在糖尿病神经痛中作用的研究

The role of HCN4 channels in rat spinal dorsal horn in diabetic neuropathic pain

目的:观察脊髓背角超极化激活环核苷酸门控通道4(HCN4)在糖尿病神经痛(DNP)发生与发展过程中的作用。方法:选择4～5周龄SD大鼠,随机分为3组:对照组、链脲佐菌素STZ组和ZD7288+STZ组。单次腹腔注射60 mg/kg STZ制备大鼠糖尿病模型,注射STZ 2周后鞘内给予HCN通道拮抗剂ZD7288。采用von Frey丝测定机械性缩足反射阈值(MWT),Western Blot法检测大鼠脊髓背角HCN4通道表达,ELISA法检测背角cAMP含量。结果:大鼠腹腔注射STZ 2周后MWT明显缩短,产生糖尿病神经痛,鞘内给予HCN通道拮抗剂ZD7288可显著延长糖尿病大鼠的MWT; DNP大鼠脊髓背角HCN4通道表达及c AMP含量显著增高,鞘内注射ZD7288可显著降低DNP大鼠脊髓背角HCN4通道表达及c AMP含量的升高。结论:脊髓背角HCN4通道表达增加促进了糖尿病神经痛的发生和发展,cAMP含量增加可能参与了HCN4通道的作用。

Objective: To explore the role of hyperpolarization-activatedcyclic nucleotide-gated channels 4( HCN4 in spinal dorsal horn in diabetic neuropathic pain( DNP). Methods: Healthy male SD rats( 4 ~ 5 weeks old) were divided into 3 groups: sham group,STZ group( intrathecal injection of saline),ZD7288 + STZ group( intrathecal injection of 30 μg ZD7288). Diabetes model was prepared by single intraperitoneal injection of 60 mg/kg streptozotocin( STZ). HCN channel blockers ZD7288 was intrathecally given to diabetic rats after injection of STZ for 2 week. MWT was detected at 1 d before and 1,2,3 and 4 week after STZ injection by using von Frey filament. HCN4 channels expression in spinal dorsal horn was detected by Western Blot. The content of c AMP in the spinal dorsal horn was detected by ELISA. Results: MWT in DNP group was significantly lower than that in sham group. Intrathecal administration of ZD7288( HCN channels antagonist,30 μg) markedly suppressed the decrease of MWT after injection of STZ. Western Blot results showed that the expression of HCN4 in spinal dorsal horn was markedly enhanced after STZ injection.The content of c AMP was also markedly enhanced in spinal dorsal horn of diabetic rats. Intrathecal administration of ZD7288 markedly suppressed the increase of HCN4 expression and c AMP content in the spinal dorsal horn of diabetic rats. Conclusion: Our findings indicate that activation of HCN4 channels in spinal dorsal horn facilitates the pathogenesis of diabetic neuropathic pain,and the increased spinal c AMP levels may be involved in the effect of HCN4 channels.