激活蓝斑在孤束核水平对迷走神经传入的抑制

ACTIVATION OF LOCUS COERULEUS INHIBITS VAGAL INPUTS IN NUCLEUS TRACTUS SOLITARIUS

在戊巴比妥钠麻醉兔，电刺激颈迷走神经中枢端，在同侧孤束核（NTS）区可记录到一个由三个子波组成的复合电位。它们的潜伏期分别为6．8±0．6ms（P1），25．8±4．2ms（P2）和89．1±2．7ms（P3）。这可能代表着不同性质的迷走传入纤维的突触后电位。同侧蓝斑（LC）内微量注射谷氨酸钠使P2，P3波的幅值明显降低。电刺激LC在同侧NTS区诱发出111个有反应单位，其潜伏期平均为6．3±1．4ms。在169个对迷走传入刺激有反应的NTS单位中，有90个对LC刺激也有反应。39个（占43．3％）会聚性单位对上述两种刺激的反应相似，而其余的呈不同的反应。对LC和迷走刺激分别均呈兴奋反应的25个NTS单位中，如预先刺激LC，则有14个单位对迷走刺激的兴奋反应受到明显抑制，另11个单位的兴奋反应完全被抑制。上述结果提示：激活蓝斑核具有抑制NTS对迷走传入刺激反应的作用。

On pentobarbital anesthetized rabbits, a three-wavelet compound potential to cervical vagal afferent stimulation was recorded in ipsilateral nucleus tractus solitarius(NTS). The latency of the three wavelets (P1, P2 and P3) was 6. 8±0. 6 ms(P1 ), 25. 8± 4. 2 ms (P2) and 89. ± 2. 7 ms (P3) respectively, which might represent postsynaptic activity of different kinds of vagal afferent fibers. Microinjection ofglutamate into ipsilateral locus coeruleus (LC) decreased the amplitude of P2 and P3 significantly. Electrical stimulation of LC could activate 111 units in ipsilateral NTS witha mean latency of 6. 3±1. 4 ms. of the 169 units in the NTS to vagal afferent stimulation, 90 units also responded to LC stimulation. 39 (43. 3% ) of the ninety, unitsshows similar response to both stimuli, while the rest show different response. Of the25 units which showed excitatory response to both LC and vagal stimulation, but whenLC stimulation was followed by vagus stimulation, the latterl s response was eithermarkedly suppressed (14 units) or completely inhibited (11 units). These resultsshowed that activation of LC exerts an inhibitory effect on the responses of the NTS tovagal afferent stimulation.