异丙酚不同麻醉深度下兔脑5-羟色胺代谢水平的变化

Effect of different depths of propofol anesthesia given by TCI on 5-HT metabolism in brain

目的 研究异丙酚不同麻醉深度下兔脑5-羟色胺(5-HT)代谢水平的改变。方法 选日本大耳兔40只,年龄8月～2岁,体重2～3kg,雌雄不拘。10只兔颈外静脉连接Graseby3500注射泵进行靶控输注(TCI)。应用异丙酚TCI系统,确定不同麻醉深度下所需的异丙酚靶控血药浓度。以咀嚼反射消失作为浅麻醉标志,以夹尾后无体动反应为深麻醉。30只日本大耳兔随机分为三组:对照组、浅麻醉组和深麻醉组(各10只)。1h后断头处死,迅速冰上分离大脑皮层、海马和丘脑并匀浆,测定5-HT及5-羟吲哚醋酸(5-HIAA)的含量。观察异丙酚不同麻醉深度下兔大脑皮层、海马和丘脑5-HT代谢水平的改变。结果 大脑皮层5-HT水平在麻醉后显著性增加,海马5-HT水平和丘脑5-HIAA水平随麻醉浓度的增加而显著性降低。结论 异丙酚显著性增加大脑皮层和丘脑的5-HT活性,降低海马区5.HT的活性,表明5-HT在异丙酚的麻醉作用机制中发挥一定的作用。

Objective To investigate the effect of different levels of propofol anesthesia on 5-HT metabolism in brain. Methods Forty Japanese Long-ear rabbits of both sexes, aged 8 months-2yr, weighing 2-3 kg were used for study. Anesthesia was induced and maintained with propofol administered by a TCI system. Blood propofol concentration required for different depths of anesthesia, as indicated by BIS monitoring and loss of chewing reflex (light anesthesia) and loss of response to tail nipped (deep anesthesia), was determined by high-performance liquid chromatography(HPLC) in 10 rabbits. Thirty rabbits were randomly divided into 3 groups often animals in each group: (1) control group received no propofol; (2) light anesthesia group and (3) deep anesthesia group. Different depths of propofol anesthesia were maintained for 1 h. At the end of one hour propofol anesthesia the animals were decapitated. Brain was immediately removed and cerebral cortex, hippocampus and thalamus were separated on ice. Their contents of 5-HT and 5-hydroxyindole-3-acetic acid (5-HIAA) were measured by spectrophoto-fluorometer.Results 5-HT content of cerebral cortex was significantly increased after anesthesia. 5-HT content of hippocampus and 5-HIAA content of thalamus decreased significantly with increasing anesthetic depth. Conclusion Propofol improves 5-HT activity in cerebral cortex and thalamus and decreases 5-HT activity in hippocampus indicating that 5-HT metabolism may be involved in the mechanism of propofol anesthesia.