藜芦碱致使大鼠背根神经节A类神经元产生触发性振荡

Triggered oscillations in type A dorsal root ganglion neurons induced by veratridine

在大鼠L5背根节浸浴钠通道失活门阻断剂藜芦碱 (veratridine) ,记录该背根节神经元A类单纤维传入放电。发现 :浸浴藜芦碱 (1 8～ 3μmol/L) 10min后 ,触压皮肤感受野或刺激坐骨神经引起部分静息纤维产生高频放电 ,其放电峰峰间期 (interspikeinterval,ISI)形成U字形等型式的振荡 ,称之为触发性振荡。刺激脉冲的间隔越大 ,触发该振荡所需要的刺激脉冲数也就越多 ;不同时程和形式的刺激引起触发性振荡的形式无明显差异 ;触发性振荡的后抑制时期一般为 30～ 90s。另外 ,实验还观察到该触发性振荡可由同一神经刺激引起的传入冲动触发。上述结果表明 ,用藜芦碱处理可使初级感觉神经元产生一种触发性振荡 ,该振荡机制可能与触发痛的发作有关。

Veratridine, a blocker of inactive gate of sodium channel, was used to perfuse L5 dorsal root ganglion (DRG) topically. Afferent activities of type A single fiber from these DRGs were recorded. It was found that after a 10-min bath of veratridine (1.8～3 μmol/L), some of the primary silent DRG neurons were triggered by touch or pressure on the receptive fields or by electrical stimulation of the sciatic nerve to produce high-frequency firing, which was termed triggered oscillation presenting a U-type of interspike intervals (ISI) or other types of oscillations. The longer the intervals between stimulating pulses, the more stimulating pulses were needed to trigger the oscillation. The oscillation, triggered by electric stimuli with different duration or patterns, had no significant difference in their patterns. The duration of the inhibitory period after a triggered oscillation was generally 30～90 s. It was also observed that this kind of triggered oscillation was induced by afferent pulses of the same neurons. These results suggest that triggered oscillation, which may contribute to the fit of triggered pain, can be produced in primary sensory neurons after application of veratridine.