A striking result from epidemiological studies show a correlation between low alcohol intake and lower incidence for
ischemic stroke and severity of derived
brain injury. Although reduced apoptosis and
inflammation has been suggested to be involved, little is known about the mechanism mediating this effect in vivo. Increase in intracellular
chloride concentration and derived depolarizing GABAAR-mediated transmission are common consequences following various
brain injuries and are caused by the abnormal expression levels of the
chloride cotransporters NKCC1 and KCC2. Downstream pro-apoptotic signaling through p75NTR may link GABAA depolarization with post-injury neuronal apoptosis. Here, we show that changes in GABAergic signaling, Cl- homeostasis, and expression of
chloride cotransporters in the post-traumatic mouse brain can be significantly reduced by administration of 3%
ethanol to the
drinking water.
Ethanol-induced upregulation of KCC2 has a positive impact on neuronal survival, preserving a large part of the cortical peri-
infarct zone, as well as preventing the massive post-ischemic upregulation of the
pro-apoptotic protein p75NTR. Importantly, intracortical multisite in vivo recordings showed that
ethanol treatment could significantly ameliorate
stroke-induced reduction in cortical activity. This surprising finding discloses a pathway triggered by low concentration of
ethanol as a novel therapeutically relevant target.