电刺激迷走神经对内毒素休克大鼠血压的影响

Effects of Vagus Nerve Electrical Stimulation on LPS-induced Hypotension in Rats

目的 研究电刺激迷走神经对内毒素 ( L PS)休克大鼠血压的影响。方法 4组雄性 Wistar大鼠 ,切断大鼠双侧颈部迷走神经干或做假手术对照 ,将左侧迷走神经干远端连接刺激电极 ,于静脉滴注 L PS( 10 m g· kg- 1 )即刻持续电刺激 ( 5 V、2 ms、1Hz) ,同时监测平均动脉压 ( MABP) ,并于静脉滴注 L PS后 1h检测各组血 TNF- α及皮质醇水平。结果 迷走神经电刺激能缓解 L PS引起的低血压休克 ,同时使血 TNF- α水平较 L PS组显著降低( 10 5 .39± 2 1.5 2 ) pg/ml,较 ( 12 9.80± 2 6 .5 6 ) pg/ml,P <0 .0 5 ;迷走神经切断能加快 L PS休克的产生 ,使 MABP下降 5 0 %的时间提前 ( 9.6 5± 0 .5 3) m in比 ( 2 5 .72± 3.0 7) min,P <0 .0 5 ,且使血 TNF- α水平显著上升 ( 15 9.0 7± 2 1.94 ) pg/ml比 ( 12 9.80± 2 6 .5 6 ) pg/m l,P <0 .0 1,血皮质醇水平显著下降 ( 34.89± 3.14 ) ng/m l比 ( 4 2 .83±2 .88) ng/ml,P <0 .0 1。结论 电刺激迷走神经可以改善 L PS休克大鼠的低血压 ,而切断迷走神经可使休克症状加重 ,这种现象与迷走神经影响体内炎症介质的合成与皮质激素的分泌有关。

OBJECTIVE To study the effects of vagus nerve electrical stimulation on the LPS-induced hypotension in rats. METHODS Forty Wistar rats were randomly divided into 4 groups. Animals were subjected to bilateral cervical vagotomy, or a comparable sham surgical procedure in which the vagus nerves were isolated but not transected. The distal end of a vagus nerve trunk was placed across bipolar electrodes connected to a stimulation module and controlled by an acquisition system. Stimuli with constant voltage (5V, 2ms, 1Hz) were applied to the nerve after administration of LPS (10mg·kg -1 , E. coli O111∶B4, Sigma), and the mean arterial blood pressure (MABP) was monitored. Blood samples of these rats were collected at 1h after LPS administration in all groups. TNF-α and corticosterone in serum were determined. RESULTS The electrical stimulation of the efferent vagus nerve significantly decreased the development of LPS-induced hypotension and TNF contents in serum (105.39±21.52 vs LPS group 129.80±26.56 pg/ml, P<0.05), and vagotomy significantly shortened the time to development of shock compared with sham-operated controls (time to 50% drop in MABP; 9.65± 0.53 min vs 25.72±3.07 min, P<0.05) and increased TNF and decreased corticosterone contents in serum (159.07±21.94 vs 129.80±26.56 pg/ml, P<0.01; 34.89±3.14 vs 42.83±2.88 ng/ml, P<0.01). CONCLUSIONS The electrical stimulation of the efferent vagus nerve could significantly attenuate the development of LPS-induced hypotension. Vagotomy could significantly shorten the time to development of shock compared with sham-operated controls. The results suggested that stimulation of efferent vagus nerve activity downregulate systemic TNF production and the development of shock during lethal endotoxemia.