摘要：

Here, we show that the synaptic vesicle protein SV2A is the brain binding site of levetiracetam (1EV), a new antiepileptic drug with a unique activity profile in animal models of seizure and epilepsy. The 1EV-binding site is enriched in synaptic vesicles, and photoaffinity labeling of purified synaptic vesicles confirms that it has an apparent molecular mass of ≈90 kDa. Brain membranes and purified synaptic vesicles from mice lacking SV2A do not bind a tritiated 1EV derivative, indicating that SV2A is necessary for LEV binding. 1EV and related compounds bind to SV2A expressed in fibroblasts, indicating that SV2A is sufficient for LEV binding. No binding was observed to the related isoforms SV2B and SV2C. Furthermore, there is a high degree of correlation between binding affinities of a series of 1EV derivatives to SV2A in fibroblasts and to the LEV-binding site in brain. Finally, there is a strong correlation between the affinity of a compound for SVZA and its ability to protect against seizures in an audiogenic mouse animal model of epilepsy. These experimental results suggest that SV2A is the binding site of 1EV in the brain and that 1EV acts by modulating the function of SVZA, supporting previous indications that 1EV possesses a mechanism of action distinct from that of other antiepileptic drugs. Further, these results indicate that proteins involved in vesicle exocytosis, and 5V2 in particular, are promising targets for the development of new CNS drug therapies.

展开