High-frequency stimulation of the hippocampus protects against seizure activity and hippocampal neuronal apoptosis induced by kainic acid administration in macaques.

Kainic acid (KA) administration is known to cause seizures and neuronal death in the hippocampus. High-frequency stimulation (HFS) of the hippocampus can be a promising method in the treatment of epilepsy while the mechanism of action is unknown yet. It remains unknown whether HFS is neuroprotective for hippocampal neurons following KA-induced seizures in macaques, although HFS has neuroprotective effects in animal models of Parkinson's disease. We therefore examined the effects of HFS on KA-induced seizures and neuronal survival in macaque's hippocampus. Seizure frequency following KA that led to seizures in macaques was strongly reduced by HFS of the hippocampus. In addition, administration of KA led to marked neuronal apoptosis in the hippocampus, accompanied by increased levels of Bax, activated caspase-3 and decreased levels of Bcl-2. HFS was found to attenuate changes in apoptosis-related proteins and robustly decreased neuronal loss following KA administration. These data indicate that hippocampal HFS can protect hippocampal neurons against KA neurotoxicity, and that HFS neuroprotection is likely to operate with inhibition of apoptosis.