AIMTo explore IL-6 neuroprotection against glutamate-induced neurotoxicity and primary mechanisms involved in this neuroprotection.

METHODSThe 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 Ca2+ levels and expression of gp130 mRNA, a 130-kDa intracellular IL-6 signal-transduction protein, in the neurons.

RESULTSThe 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 Ca2+ 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.

CONCLUSIONIL-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 Ca2+ overload and mediated by gp130 intracellular signal transduction pathways.