Augmentation of M-type (KCNQ) potassium channels as a novel strategy to reduce stroke-induced brain injury

Cerebral ischemic stroke is a worldwide cause of mortality/morbidity and thus an important focus of research to decrease the severity of brain injury. Therapeutic options for acute stroke are still limited. In neurons throughout the brain, "M-type" K(+) currents, underlain by KCNQ subunits 2-5, play dominant roles in control over excitability, and are thus implicated in myriad neurological and psychiatric disorders. Although KCNQ channel openers, such as retigabine, have emerged as anti-epilepsy drugs, their effects on ischemic injury remain unknown. Here, we investigated the protective effects of M-channel openers on stroke-induced brain injury in mouse photothrombotic and middle cerebral artery occlusion (MCAo) models. Both photothrombosis and MCAo led to rapid, predictable, and consistently sized necrotic brain lesions, inflammatory responses, and behavioral deficits. Administration of three distinct M-channel openers at 0-6 h after ischemic injury significantly decreased brain infarct size and inflammation, and prevented neurological dysfunction, although they were more effective when administered 0-3 h poststroke. Thus, we show beneficial effects against stroke-induced brain injury and neuronal death through pharmacological regulation of ion channels that control neuronal excitability.