Neuropeptide Y delays hippocampal kindling in the rat

Chronic intrahippocampal infusion of the neurotrophin brain-derived neurotrophic factor (BDNF) has been shown to delay kindling epileptogenesis in the rat and several lines of evidence suggest that neuropeptide Y could mediate these inhibitory effects. Chronic infusion of BDNF leads to a sustained overexpression of neuropeptide Y in the hippocampus, which follows a time course similar to that of the suppressive effects of BDNF on kindling. In vivo, acute applications of neuropeptide Y or agonists of its receptors exert anticonvulsant properties, especially on seizures of hippocampal origin. In this study, we examined how chronic infusion of this neuropeptide in the hippocampus affected kindling epileptogenesis. A 7-day continuous infusion of neuropeptide Y in the hippocampus delayed the progression of hippocampal kindling in the rat, whereas anti-neuropeptide Y immunoglobulins had an aggravating effect. These results show that neuropeptide Y exerts anti-epileptogenic properties on seizures originating within the hippocampus and lend support to the hypothesis that BDNF delays kindling at least in part through upregulation of this neuropeptide. They also suggest that the seizure-induced upregulation of neuropeptide Y constitutes an endogenous mechanism counteracting excessive hippocampal excitability.