EAAT2 (glutamate transporter, positive allosteric modulator)

Class

first-in-class, orally available small molecule; highly selective positive allosteric modulator of the astrocytic glutamate transporter EAAT2

Pathway

enhances EAAT2-mediated glutamate reuptake by astrocytes, restoring synaptic glutamate balance and reducing excitotoxicity/hyperexcitability that drives seizure activity

EAAT2 (excitatory amino acid transporter 2, also called GLT-1) is the principal transporter responsible for clearing glutamate, the brain's main excitatory neurotransmitter, from the space between neurons after it has activated its receptors. This clearance occurs mainly through astrocytes, the glial cells that ensheath synapses, and EAAT2 accounts for the large majority of glutamate reuptake in the central nervous system. When glutamate is not cleared efficiently, it can over-activate receptors on nearby neurons, promoting hyperexcitability and, over time, excitotoxic injury—a process implicated in seizure disorders, amyotrophic lateral sclerosis, ischemic brain injury, and some neurodegenerative conditions. A positive allosteric modulator of EAAT2 binds the transporter at a site distinct from where glutamate itself binds, enhancing its transport efficiency rather than substituting for it. This approach aims to restore a more physiological balance of synaptic glutamate by boosting the brain's own clearance machinery, rather than blocking receptors directly, which can carry different side-effect trade-offs. Because this mechanism targets a process common to many conditions involving excitatory imbalance, it is of particular interest in disorders such as epilepsy, where reducing excessive excitatory signaling could lessen seizure activity, as well as in other diseases characterized by glutamate-driven neuronal stress.