海马θ振荡参与迷走神经刺激术抗癫痫作用

Hippocampal θ oscillation involved in antiepilepsy effects of vagus nerve stimulation

目的观察弱电刺激迷走神经中枢端对正常及痫样放电大鼠海马CA1区细胞放电及场电的影响。方法SD雄性大鼠55只(150～250g),SPF级。分对照组45只和青霉素致规则痫样放电组10只。第1组分离其颈部左侧迷走神经,结扎外周端,弱电(10Hz,0.5ms,1.5～5.0V,15～20个/串)刺激迷走神经,每5min刺激1次,共20次。记录右侧海马CA1细胞放电及双侧海马CA1场电。第2组是在第1组的方法中用浸有青霉素钠溶液的明胶海绵(400～600u/mm3)置于左侧皮层诱发痫样放电,待稳定30min后进行实验。结果第1组大鼠双侧场电出现3～6.5Hz的周期性theta电振荡(38/45,84.4%),伴有theta-on(n=30)和theta-off(n=5)两种形式细胞放电。第2组大鼠痫样放电尖波电压幅度降低,尖波间隔延长(n=10)。痫样放电尖波间隔出现theta振荡,伴细胞紧张性放电(n=10)。细胞放电的动作电位个数与痫样放电尖波间隔呈正相关(P<0.001),与痫样放电尖波电压降无相关性。结论海马theta振荡可能参与迷走神经刺激术抗癫痫作用,海马theta-on细胞可能参与抑制癫痫发生频率。

Objective To study the effects of acute weak vagus nerve stimulation on hippocampal CA1 unit dischar- 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 and theta-off（n = 5）. The sharp wave amplitude was inhibited while the sharo . It has two kinds ： theta-on （ n = 30） 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 〈 O. 001 ）, but there was no correlation with sharp wave potential amplitude. Conclusion Inhibition of epileptiform activity induced by the acute weak stimulation maybe explained by the appearing of theta oscillation. The theta-on cell is very important to the field sharp waves frequency inhibition.