凋亡是一种程序性细胞死亡,是神经元损伤重要方式之一。凋亡相关基因(bax, bcl-x 和 bad)启动凋亡过程,而其它基因(bcl-2, ced-9)则抑制凋亡,两者相互制衡[12]。丙泊酚明显抑制缺血再灌注后海马CAI区锥体细胞凋亡,减少延迟性神经元死亡[13]。丙泊酚对谷氨酸盐、同型半胱氨酸,buthionine sulfoximine,过氧化氢诱导的鼠脑皮质和海马区HT-2神经元凋亡亦有良好抑制作用[14]。基于大鼠体外循环模型,我们既往的研究也表明体外循环可引起大鼠海马CA1区神经元凋亡,明显升高bax和bcl-2 mRNA表达,加重神经元病理损伤,且随着体外循环时间的延长而进一步加重损伤[15]。<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> 本研究表明丙泊酚10mg.kg-1.h-1静脉给药明显抑制海马神经元凋亡,减轻神经元病理损伤,增加bcl-2蛋白表达, 抑制bax蛋白表达,但是对于循环系统抑制作用明显。而小剂量的丙泊酚静脉输注对神经元凋亡及bcl-2和bax mRNA表达却没有明显影响。同样剂量丙泊酚经颈内动脉输注却能够产生与大剂量丙泊酚静脉应用相似的保护作用,明显抑制神经元凋亡,减轻体外循环对中枢神经系统的病理损伤,并且对血压和心率的影响轻微,不产生循环抑制。 综上所述,小剂量丙泊酚颈内动脉连续输注,可通过抑制凋亡减轻体外循环下中枢神经系统的病理损伤而产生脑保护作用,同时避免了大剂量丙泊酚输注对循环系统的抑制作用,从而为丙泊酚动脉输注的药效学和丙泊酚的脑保护提供全新的尝试。 参考文献 1 Kahveci FS, Kahveci N, Alkan T et al.Propofol versus isoflurane anesthesia under hypothermic conditions: effects on intracranial pressure and local cerebral blood flow after diffuse traumatic brain injury in the rat.Surg Neurol,2001;56:206-14 2 金沐,孙来保,谭洁芳 et al.浅低温体外循环围术期丙泊酚的脑保护效应.中华麻醉学杂志,2003;23:587-91 3 Mackensen G,Burkhard MD. Cardiopulmonary Bypass Induces Neurologic and Neurocognitive Dysfunction in the Rat, Anesthesiology,2001;95:1485-91 4 Seines OA, Goldsborough MA, Borowicz LM et al. Neurobehavioural sequelae of cardiopulmonary bypass. Lancet, 1999;353: 1601-9 5 Gauss A, Heinrich H, Wilder-Smith OH. Echocardiographic assessment of the haemodynamic effects of propofo: a comparison with etomidate and thiopentone.Anaesthesia,1991;46:99-105 6 Murphy EJ. Intra-arterial injection of metoclopramide, midazolam, propofol and pethidine. Anaesth Intensive Care,2002;30:367?9 7 Silva TM, Hernandez-Fustes OJ, Bueno ML et al.The Wada test with propofol in a patient with epilepsy. Ar Qneuropsiquiatr, 2000; 58: 348?50 8 Jones DR, Hall SD, Jackson EK et al. Brain uptake of benzodiazepines: Effects of lipophilicity and plasma protein binding. J Pharmacol Exp Ther,1988;245: 816-22 9 秦晓辉,米卫东,张宏,et al. 异丙酚对神经元缺氧损伤的保护及其作用机制. 中国药理学通报,2003; 19:1024-72 10张树平,王建波,王巧云,et al.不用剂量异丙酚对大鼠血流动力学的影响.中国药理学通报,1996;12:191-2 11 Wang M, Joshi S, Emerson RG. Comparison of Intracarotid and Intravenous Propofol for Electrocerebral Silence in Rabbits. Anesthesiology, 2003;99:904-10 12 ZHOU Haiyan,MA Yuefeng,ZHOU Feng et al.Effects of magnesium sulfate on neuron apoptosis and expression of caspase-3,bax and bcl-2 after cerebral ischemia-reperfusion injury .Chinese Medical Journal,2003;116:1532-4 13 Kodaka M, Mori T, Tanaka K et al. Depressive effects of propofol on apoptotic injury and delayed neuronal death after forebrain ischemia in the rat--comparison with nitrous oxide-oxygen-isoflurane.Masui,2000;49:130-8 14 Sagara Y, Hendler S, Khoh-Reiter S et al. Propofol hemisuccinate protects neuronal cells from oxidative injury.J Neurochem,1999;73:2524-30 15 张挺杰,杭燕南. 体外循环对大鼠海马CA1区神经元凋亡的影响.中华麻醉学杂志,2004;24:20-4 |