Background

Heavy ethanol consumption is widely accepted as a risk for ischemic stroke. The molecular mechanisms of ethanol-induced brain injury have not been fully understood.

Aim

This study aims to find out the mechanism of the ischemic cerebral injury.

Methods

We used Sprague-Dawley rats with transient middle cerebral artery occlusion for acute experiment and stroke-prone spontaneously hypertensive rats for long-term experiment in vivo, and oxygen-glucose deprivation model in vitro to define a detrimental effect of different doses of ethanol on ischemic stroke injury. We also used mitochondrial aldehyde dehydrogenase 2 knockdown/overexpression or inhibitor/activator to investigate mechanism of the adverse effects of ethanol.

Results

High-dose ethanol (36% of calorie derived from ethanol) significantly increased the infarct size in rats (P < 0·01) and decreased the survival time of stroke-prone spontaneously hypertensive rats by about 20%. Six-week treatment with high-dose ethanol changed a distribution of isoelectric point of aldehyde dehydrogenase 2 and inhibited aldehyde dehydrogenase 2 activity in brain. High dose of ethanol increased the cerebral acetaldehyde level, and increased 4-hydroxy-2-nonenal and malondialdehyde in serum of rats with middle cerebral artery occlusion. The activator of aldehyde dehydrogenase 2, Alda-1 abolished neuronal cells death and ischemic injury induced by ethanol and the inhibitor reversed the injurious effects. An overexpression of aldehyde dehydrogenase 2 completely abolished the increased infarct size and neurological deficit score by ethanol. Conversely, knockdown of aldehyde dehydrogenase 2 increased the infarct size and exaggerated the cerebral injury induced by ethanol.

Conclusions

High concentrations of ethanol aggravate cerebral injury by inhibiting of aldehyde dehydrogenase 2 and inducing excess accumulation of aldehydes.