Neuroprotective role of lactate in a human in vitro model of the ischemic penumbra

In patients suffering from cerebral ischemic stroke, there is an urgent need for treatments to protect brain cells. Recently, treatment strategies that induce neuronal activity have been shown to be neuroprotective. However, the biological mechanisms underlying the benefit from neuronal activation are unknown. We hypothesized that neuronal activation might trigger the astrocyte-to-neuron lactate shuttle, whereby lactate is released from astrocytes to support the energy requirements of hypoxic neurons, and this leads to the observed neuroprotection. We tested this by establishing a human cell based in vitro model of the ischemic penumbra. We found that lactate transporters are involved in the neuroprotective effect mediated by neuronal activation, that lactate exogenously administered before hypoxia correlated with neuroprotection, and that stimulation of astrocyte with consequent endogenous production of lactate resulted in neuroprotection. We presented evidence that lactate contributes to neuroprotection during hypoxia providing a potential basis for therapeutic approaches in ischemic stroke.