IL6 and brain injury: Our result showed significantly lower IL-6 mRNA expression levels in the brains of propofol-treated wild-type mice than in the brains of control mice, which is consistent with an earlier study in which there was a correlation between infarct volume and IL-6 mRNA expression in the brain [33] Among various pro-inflammatory cytokines, IL-6 plays pivotal roles in local inflammation and cytotoxicity after ischemic brain injury and is involved in the mechanism underlying the expansion of ischemic brain injury [34,35].