Many brain diseases are characterized by neuronal hyperexcitability and BBB dysfunction.  We found that neuronal activation and excessive release of the major excitatory neurotransmitter, glutamate, mediate opening of the BBB through activation of NMDA receptors. In addition, as pericytes were shown to play important role in BBB integrity and regulation of blood flow, we show that epileptic seizures induce pericytic injury which accompanied by increased microvascular permeability and impaired neurovascular coupling.