In the in vivo study, rats received 24 h permanent middle cerebral artery occlusion. NEF was administered intravenously either at 15 min post-injury but prior to the first NCS event (30 mg/kg, pre-NCS treatment) or immediately after the first NCS occurred (30 or 60 mg/kg, post-NCS treatment). In the in vitro study, neuronal cell cultures were exposed to veratridine or glutamate and treated with NEF (1-500 nM).
The NEF pre-NCS treatment significantly reduced the NCS frequency and duration, whereas the higher NEF dose (60 mg/kg) was required to achieve similar effects when given after NCS occurred. The NEF treatment also dose-dependently (5-500 nM) protected against neuronal cell death induced by veratridine as measured by MTT cell viability assay, but higher doses (250-500 nM) were required against glutamate toxicity.
The anti-seizure property of NEF was demonstrated in a clinically relevant rat model of post-ischemic NCS. The preferential effects of NEF against in vitro veratridine toxicity suggest the involvement of its modulation of sodium channel malfunction. Future studies are warranted to study the mechanisms of NEF against ischemic brain injury and post-ischemic seizures.