Brainstem regions affecting minimum alveolar concentration and movement pattern during isoflurane anesthesia.
Brainstem regions affecting minimum alveolar concentration and movement pattern during isoflurane anesthesia.
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DOI：
10.1097/aln.0b013e3181c81319
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发表时间：
2010-02
期刊：
影响因子：
8.8
通讯作者：
Chan YM
中科院分区：
文献类型：
--
作者：
Jinks SL;Bravo M;Satter O;Chan YM
脊髓横断或选择性地将挥发性麻醉剂输送到脊髓可降低最小肺泡浓度(MAC)，而去丘脑前部则不能。作者试图确定哪些脑干区域影响异氟醚的麻醉需求和运动反应。测量成年大鼠去大脑前后在前、中、桥、髓或去大脑水平的运动(股二头肌肌电)和MAC。其他实验评估了利多卡因灭活中脑运动区对MAC的影响，以及异氟醚对该区域伤害性神经元反应的影响。横断位于中丘、脑桥头端和桥延髓交界处分别显著降低了约10%、40%和45%的MAC值。在中缝大核尾侧、网状背核吻侧的延髓中部横断后，MAC值下降了9%，但只发生了微弱的、单一的运动。尾侧延髓横断在OBEX处减少了60%的MAC。利多卡因使双侧中脑运动区失活，导致MAC可逆性下降32%，并减少了MAC以下异氟醚浓度下的运动次数和幅度。1.2MAC异氟醚可使中脑运动区神经元对超大伤害性尾夹的反应降低87%。作者得出结论，中脑运动区通过促进腹侧脊髓运动回路影响麻醉需求，并促进MAC下异氟醚的重复运动，麻醉剂似乎在腹侧脊髓运动回路中发挥关键的固定作用。然而，脑干对MAC的净影响似乎是下行伤害性感受和运动调节通路相互作用的结果。
Spinal transection or selective delivery of volatile anesthetics to the spinal cord reduces minimum alveolar concentration (MAC), whereas precollicular decerebration does not. The authors sought to determine which brainstem regions influence anesthetic requirements and movement responses with isoflurane. Movement (biceps femoris electromyogram) and MAC were measured in adult rats before and after decerebration at the precollicular, mid-collicular, pontine or medullary level, or decerebellation. Additional experiments assessed the effects of lidocaine inactivation of the mesencephalic locomotor region on MAC and the effects of isoflurane on nociceptive neuronal responses in this region. Transections placed at the level of the mid-colliculus, rostral pons, and pontomedullary junction significantly reduced MAC by approximately 10, 40, and 45%, respectively. MAC was decreased 9% after mid-medullary transections that were placed caudal to the nucleus raphe magnus but rostral to the dorsal reticular nucleus; however, only weak, single movements occurred. Caudal medullary transections at the obex decreased MAC by 60%. Bilateral inactivation of the mesencephalic locomotor region with lidocaine caused a reversible, 32% decrease in MAC and reduced the number and amplitude of movements at sub-MAC isoflurane concentrations. Neuronal responses of mesencephalic locomotor region neurons to supramaximal noxious tail clamp were reduced by 87% by 1.2 MAC isoflurane. The authors conclude that the mesencephalic locomotor region influences anesthetic requirements and promotes repetitive movement with sub-MAC isoflurane by facilitating ventral spinal locomotor circuits, where anesthetics seem to exert their key immobilizing effects. However, net brainstem influences on MAC seem to result from interaction among descending nociceptive and locomotor modulatory pathways.