异丙酚和氯胺酮对大鼠内侧膝状体腹侧核团中潜伏期听觉诱发电位的影响

Effects of propfol and ketamine on mid-latency auditory evoked potential in the ventral partition of medial geniculate body of rat

目的研究异丙酚和氯胺酮对大鼠内侧膝状体腹侧核团中潜伏期听觉诱发电位（MLAEP）的影响。方法72只SD大鼠，随机分成12组（n=6），采用核团内微量药物注射的方法，生理盐水组（NS组）内侧膝状体腹侧核团内注射生理盐水0．2m，异丙酚溶媒脂肪乳组（I组）注射等容量脂肪乳，5．6μmol／L异丙酚组（P1组）、16．8μmol／L异丙酚组（P1组）、56μmol／L异丙酚组（P3组）、168μmol／L异丙酚组（P4组）、560μmol／L异丙酚组（B组）、18μmol／L氯胺酮组（K1组）、54μmol／L氯胺酮组（K2组）、180μmol／L氯胺酮组（K组）、540μmol／L氯胺酮组（K4组）和1800μmol／L氯胺酮组（I（5组）注射相应剂量异丙酚或氯胺酮（0．2m）。分别于给药前1min、给药后1min记录MLAEP，包括No波、Po波、Na波、Pa波和Nb波的潜伏期及Pa波的波幅。结果与给药前比较，NS组、Ⅰ组、P1组、P2组、K1组、K2组、K3组、K4组、k5组给药后MLAEP的各指标差异无统计学意义（P〉0．05），P3组、P4组和P5组给药后NA波、PA波和NB波的潜伏期延长，PA波的波幅下降（P〈0．05）；与NS组、Ⅰ组和P1组比较，P3组、P4组和P5组Na波、Pa波和Nb波的潜伏期延长，Pa波的波幅下降（P〈0．05）。结论5．6、16．8、56、168和560μmol／L（0．2μl）异丙酚对大鼠内侧膝状体腹侧核团MLAEP产生剂量依赖性的抑制作用，而18、54、180、540和1800μmol／L（0．2μ1）氯胺酮对其无影响。

Objective To investigate the effects of propofol and ketamine on mid-latency auditory evoked potential （MLAEP） in the ventral partition of medial geniculate body （MGBv） of rat. Methods Seventy-two SD rats of either sex weighing 250-300 g were randomly divided into 12 groups （ n = 6 each） ： group 1 normal saline （NS）; group Ⅱ intralipid （Ⅰ）; group Ⅲ-Ⅳ 5 groups of different concentrations of propofol （5.6, 16.8, 56, 168, 580μmol/L） （P1-5） and group Ⅷ-Ⅻ 5 groups of different concentrations of ketamine （18, 54, 180, 540, 1 800 μmol/L） （K1-5 ）. The animals were anesthetized with ether, tracheostomized and mechanically ventilated. After emergence from anesthesia the animals were paralyzed with vecuronium and fixed. A recording needle electrode through which drugs could be injected was inserted into MGBv by means of stereotaxis. Correct insertion was verified by MLAEP response to standard sound. MLAEP including amplitudes and latencies of N0, P0, Na, Pa and Nb waves were recorded 1 min before and after injection of 0.2μl propofol, ketamine, normal saline or intralipid. Results There was no significant change in all waves of MLAEP in MGBv after drug administration as compared with the baseline before injection in group NS, I, P1, P2, K1,2,3,4.5. The latency of Na, Pa and Nb waves was significantly prolonged and the amplitude of Pa wave was decreased after injection as compared with the baseline in group P3,4,5. The latency of Na, Pa and Nb waves was significantly longer and the amplitude of Pa wave was significantly lower in group P3,4,5 than in group NS, I and P1 . Conclusion Propofol 5.6, 16.8, 56, 168 and 560 μmol/L in 0.2 μl intralipid can inhibit MLAEP in MGBv of rat in a dose-dependent manner, while ketamine 18, 54, 180, 540 and l 800μmol/L do not.