Enhanced Excitability of the Neonatal Rat Hippocampus After Acute Exposure to Ethanol

Abstract

Enhanced excitability manifested by seizures and epilepsy is one of the characteristic features of the fetal alcohol spectrum disorders (FASD). Here, we examined network excitability using a high-potassium model in the hippocampal slices prepared from the postnatal days of P7–9 rats treated with ethanol. Ethanol was administered at 6 g/kg intraperitoneally 12 h before the slice preparation. The extracellular field potential recordings from the hippocampal slices using multishank silicon probes placed along CA3-CA1 axis were performed in the interface chamber. We found that elevation of the extracellular potassium from 3.5 to 6 mM evoked seizure-like clonic or tonic-clonic discharges in 77 % of the slices from the ethanol-treated animals and only in 15 % of the slices from the control animals. Further elevation of the extracellular potassium to 8.5 mM evoked epileptiform activity in 92 and 69 % of the slices from the ethanol-treated and the control animals, respectively. The current source density profile and the multiple unit activity analysis pointed on the CA3 hippocampal region as a generator of the epileptiform activity. Thus, the hippocampal slices from the ethanol-treated neonatal rats display enhanced excitability and could serve as a FASD model to study the early epileptiform transformations following exposure to ethanol.