白介素-6对NMDA诱导的小脑神经元放电活动的抑制作用及其机制

Inhibitory effect of interleukin-6 on NMDA-stimulated neuronal firing activity and possible mechanism involved in the effect

目的:观察白介素-6(IL-6)对N-甲基-D-天冬氨酸(NMDA)激发的神经元放电活动的影响及其可能的作用机制。方法:用含IL-6、NMDA和JAK抑制剂AG490的人工脑脊液(ACSF)灌流小脑脑片,利用离体脑片神经元单位放电细胞外记录技术,记录药物对小脑间位核神经元放电的影响。用Western blot法测定间位核神经元NMDA受体亚单位1(NR1)的磷酸化水平。结果:单独用12.5μmol/L和25μmol/L NMDA灌流,神经元放电频率均较基础放电频率增加;用不同浓度IL-6(50,100,200ng/ml)联合NMDA作用后,神经元的放电频率出现浓度依赖性地降低;AG490可部分阻断IL-6对NMDA兴奋神经元放电的抑制作用。与单独NMDA处理组比较,用IL-6联合NMDA处理神经元后,神经元的NR1磷酸化水平出现浓度依赖性地降低。AG490可阻断IL-6所致的神经元NR1磷酸化水平的降低。结论:IL-6可抑制NMDA激发的小脑间位核神经元的放电兴奋活动;并同时下调神经元的NR1磷酸化水平。

Objective： To study the effect and the possible mechanism of IL-6 on NMDA-excited neuronal discharges of rats in vitro. Methods： The cerebellar slices were prepared and spontaneous discharges of single cerebellar interposed nuclear（IN） neurons were recorded by extracellular recordings. The cerebellar slices were perfused with artificial cerebral spinal fluid（ACSF） containing N-methyl-D-aspartate（ NM- DA）, IL-6, JAK inhibitor AG490. The changes in firing activities of the neurons treated with the drugs were recorded. The levels of phosphorylation at serine 897 site of NMDA receptor subunit 1 （ NR1 ） in the neurons treated with various drugs mentioned above were detected by Western blot. Results： The discharge rates of the neurons that were treated with IL-6 together with NMDA were significantly lower than those of the neurons treated with NMDA alone. AGd-90 partially blocked the inhibitory effect of IL-6 on the NMDA-stimulated neuronal firing activity. The treatment of the neurons with IL-6 and NMDA led to a concentration-dependent suppression of the phospho-NR1 expression relative to those neurons treated with NMDA alone. AG490 blocked the effect of the IL-6-induced depression of phospho-NR1 expression. Conclusion： IL-6 inhibits NMDA-stimulated neuronal firing activity, and simultaneously down-regulates the phosphorylation of NR1 at serine 897 site.