Hippocampal ? oscillation involved in antiepilepsy effects of vagus nerve stimulation / 基础医学与临床

ABSTRACT

Objective To study the effects of acute weak vagus nerve stimulation on hippocampal CA1 unit discharges and field potentials of normal and epileptiform discharging rats.Methods The experiments were performed with 55 male Sprague-Dawley rats weighing 180～250 g,SPF grade.Animals were divided into normal(n=45)and regularly epileptiform discharging(n=10)groups.The normal rat groupSeparate the left neck vagus nerve and ligate the peripheral end.Acute weak electrical stimulation(10 Hz,0.5 ms,1.5～5.0 V,15～20 unit /train)were administered to the left neck vagus nerve central end.20 trains were performed with a regular interval of 5 min.Record the unit discharges of right hippocampal CA1 and field potentials of bilateral hippocampal CA1.The epileptiform discharging groupGelatin spongia was put onto the left cortex to induce epileptiform discharges.After 30 min stable regularly discharging,continue the procedure in the first group.Results Cyclical theta oscillation(about 3～6.5 Hz)appeared in bilateral hippocampal CA1 of normal rats after the stimulation(strain m=5～7,38/45,84.4%).With oscillation,there is unit discharging.It has two kindstheta-on(n=30)and theta-off(n=5).The sharp wave amplitude was inhibited while the sharp wave interval increased following the acute weak vagus nerve stimulation(n=10)in epileptiform discharging rats.Theta oscillation was induced during the sharp wave.With oscillation,there is tonic unit discharging(n=10).The number of action potential spikes positively correlate with the sharp wave intervals(P