RESUMO
Objective To observe changes in hippocampal network electrical activities in electroacupuncture regulation of abnormal cardiovascular activities and explore the central mechanism of the regulation. Method Experimental rats were randomized into three groups: normal urethane anesthesia without electroacupuncture (n=15), urethane enhanced deep anesthesia (n=9) and normal anesthesia plus anal canal pressurization (n=15). Femoral arterial pressure, cardiac electricity, hippocampal field potentials and cellular discharge were recorded in the three groups. The normal anesthesia group did not receive intervention measures. The other two groups received acupuncture intervention after successful induction of abnormal blood pressure. Result In rats with normal urethane anesthesia, sleep-like periodic hippocampal electrical activity occurred with periodic cardiovascular activities and theta oscillations was corresponding to increased heart rates. In rats with deep anesthesia and hypotension, theta oscillations appeared in hippocampal network with increased blood pressure and heart rates after electroacupuncture (P<0.001). Anal canal pressurization induced increases in blood pressure and heart rates and caused theta oscillations in hippocampal network. During that time, electroacupuncture could still activate theta-related cells, reduce blood pressure and decrease heart rates (P<0.001). Conclusion Theta oscillations in hippocampal network are involved in the bidirectional regulating effect of electroacupuncture on abnormal cardiovascular activities.
RESUMO
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 group:Separate 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 group:Gelatin 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 kinds:theta-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