白介素-6保护小脑颗粒神经元抗谷氨酸的神经毒性作用

INTERLEUKIN-6 PREVENTS CULTURED CEREBELLAR GRANULE NEURONS FROM GLUTAMATE-INDUCED NEUROTOXICITY

目的:探讨白介素-6(IL-6)对谷氨酸诱导的神经元损伤的防治作用及其作用机制。方法:用IL-6慢性预处理培养的小脑颗粒神经元,然后后用谷氨酸急性刺激小脑颗粒神经元。用噻唑兰(MTT)比色法和末端脱氧核苷酸转移酶介导的原位缺口末端标记(TUNEL)法分别观察神经元的功能和凋亡的变化;用激光扫描共聚焦显微镜(LSCM)和逆转录聚合酶链式反应(RT-PCR)法分别检测神经元内Ca2+浓度的动态变化和IL-6信号转导蛋白gp130 mRNA的表达。结果:IL-6(2.5、5和10 ng/ml)慢性预处理培养的小脑颗粒神经元,可浓度依赖性地改善谷氨酸诱导的神经元活性降低;并可明显减少谷氨酸诱导的神经元凋亡;还可显著抑制谷氨酸激发的神经元内Ca2+超载。此外,经IL-6慢性预处理的小脑颗粒神经元表达gp130 mRNA明显低于未经IL-6预处理的神经元。结论:IL-6能保护神经元抵抗由谷氨酸诱导的兴奋毒性作用,IL-6的这种神经保护机制可能与它抑制神经元内Ca2+超载密切相关,而且可能由gp130细胞内信号转导途径介导。

Aim： To explore IL-6 neuroprotection against glutamate-induced neurotoxicity and primary mechanisms involved in this neuro- protection. Methods： The cerebellar granule neurons from postnatal 8-day infant rats were chronically exposed to IL-6 for 8 days, and then glutamate stimulated the cultured cerebellar granule neurons for 15 min. Methyl-thiazole-tetrazolium （MTT） assay and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling （TUNEL） method were used to observe the changes of neuronal vitality and apoptosis, respectively. Laser scanning confocal microscope （LSCM） and reverse transcription-polymerase chain reaction （RT- PCR） were respectively employed to measure dynamic changes of intracellular Ca^2＋ levels and expression of gp130 mRNA, a 130-kDa intracellular IL-6 signal-transduction protein, in the neurons. Results： The chronic IL-6 （2.5, 5 and 10 ng/ml） pretreatment of the cultured cerebellar granule neurons remarkably improved the decreased neuronal vitality by glutamate in a concentration-dependent manner. The neuronal apoptosis induced by glutamate was significantly attenuated by the chronic IL-6 pretreatment. The intracellular Ca^2＋ overload evoked by glutamate was also inhibited by the chronic IL-6 pretreatment. The expression of gp130 mRNA was dramatically lower in the IL-6-pretreated cerebellar granule neurons than in the IL-6-untreated neurons. Conclusion： IL-6 can protect neurons against glutamate-induced exciting neurotoxicity. The mechanism of IL-6 neuroprotection may be closely related to the suppression of glutamate-induced intracellular Ca^2＋ overload and mediated by gp130 intracellular signal transduction pathways.