Interleukin-6 protects cerebellar granule neurons from NMDA-induced neurotoxicity.
Interleukin-6 (IL-6) is an important cytokine that participates in inflammation reaction and cell growth and differentiation in the immune and nervous systems. However, the neuroprotection of IL-6 against N-methyl-D-aspartate (NMDA)-induced neurotoxicity and the related underlying mechanisms are still not identified. In the present study, the cultured cerebellar granule neurons (CGNs) from postnatal (8-day) infant rats were chronically exposed to IL-6 for 8 d, and then NMDA (100 micromol/L) was applied to the cultured CGNs for 30 min. Methyl-thiazole-tetrazolium (MTT) assay, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method and confocal laser scanning microscope (CLSM) were used to detect neuronal vitality, apoptosis and dynamic changes of intracellular Ca(2+) levels in the neurons, respectively. Anti-gp130 monoclonal antibody (75 ng/mL) was employed to the cultured CGNs with IL-6 to inhibit IL-6 activity so as to evaluate the role of gp130 (a 130 kDa glucoprotein transducing IL-6 signal) in mediating IL-6 neuroprotection. Western blot was used to measure the expressions of phospho-signal transducer and activator of transcription 3 (STAT3) and phospho-extracellular signal regulated kinase 1/2 (ERK1/2) in the cultured CGNs. The NMDA stimulation of the cultured CGNs without IL-6 pretreatment resulted in a significant reduction of the neuronal vitality, notable enhancement of the neuronal apoptosis and intracellular Ca(2+) overload in the neurons. The NMDA stimulation of the CGNs chronically pretreated with IL-6 caused a remarkable increase in the neuronal vitality, marked suppression of neuronal apoptosis and intracellular Ca(2+) overload in the neurons, compared with that in the control neurons without IL-6 pretreatment. Furthermore, anti-gp130 antibody blocked the inhibitory effect of IL-6 on NMDA-induced intracellular Ca(2+) overload in the neurons. The levels of phospho-STAT3 and phospho-ERK1/2 were significantly higher in IL-6-pretreated CGNs than those in IL-6-untreated neurons. The results suggest that chronic IL-6 pretreatment of CGNs protects the neurons against NMDA-induced neurotoxicity. The neuroprotective effect of IL-6 is closely related to its suppression of NMDA-induced intracellular Ca(2+) overload and is possibly mediated by gp130/JAK-STAT3 and gp130/RAS-ERK1/2 transduction pathways.
Wang
Xiao-Chun
XC
Department of Physiology, Faculty of Medicine, and Key Laboratory of Neuroregeneration of Jiangsu Province, Nantong University, Nantong, China.
Qiu
Yi-Hua
YH
Peng
Yu-Ping
YP
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015850:Interleukin-6 / Q000502:physiology*; D020935:MAP Kinase Signaling System; D016202:N-Methylaspartate / Q000037:antagonists & inhibitors / Q000633:toxicity*; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents; D051381:Rats; D017207:Rats, Sprague-Dawley; D050796:STAT3 Transcription Factor / Q000378:metabolism
D015850:Interleukin-6; D018696:Neuroprotective Agents; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D016202:N-Methylaspartate