右美托咪定对丙泊酚孵育的离体胎鼠海马神经元Bcl-2／Bax及caspase-3表达的影响

THE EFFECT OF DEXMEDETOMIDINE ON THE EXPRESSION OF BCL-2/BAX AND CASPASE-3 IN ISOLATED HIPPOCAMPAL NEURONS OF FETAL RATS INCUBATED WITH PROPOFOL

目的：评价右美托咪定对丙泊酚孵育的离体胎鼠海马神经元凋亡及相关因子（Bcl-2、Bax及caspase-3）表达的影响。方法：原代培养孕16～18d的SD大鼠胎鼠海马神经元细胞。以5×10^5／mL的细胞密度接种于培养板中，培养至第7天，NeuN法鉴定原代海马神经元。采用随机数字表法将海马神经元分为3组：对照组（C组）不做任何处理；丙泊酚组（P组）加入丙泊酚，终浓度为100μmol／L；右美托咪定＋丙泊酚组（DP组）加人右美托咪定，终浓度为1μmol／L，孵育30rain，随后加入丙泊酚，终浓度为100μmol／L，孵育3h。采用流式细胞术检测细胞凋亡情况，RT—PCR法测Bcl-2、Bax及caspase-3tuRNA的表达，Westernblotting法检测Bcl-2、Bax及actived—caspase-3蛋白的表达。结果：与C组比较，P组海马神经元细胞凋亡率升高（Pd0．05），Bcl-2mRNA及其蛋白表达下调（Pd0．05），easpase-3tuRNA和activedcaspase-3蛋白表达上调（Pd0．05），而BaxtuRNA和蛋白表达两组比较差异无统计学意义（P〉0．05），P组Bcl-2／Bax比值显著低于C组（P〈0．05）。与P组比较，DP组海马神经元细胞凋亡率降低（P〈0．05），Bcl-2mRNA和蛋白表达上调（P〈0．05），caspase-3mRNA和actived—easpase-3蛋白表达下调（Pd0．05），而BaxmRNA和蛋白表达两组比较差异无统计学意义（P〉0．05），DP组Bcl2／Bax蛋白比值显著高于P组（Pd0．05）。结论：右美托咪定通过上调Bcl—2的表达抑制下游caspase-3的激活，使离体胎鼠海马神经元凋亡减少，从而起到神经保护作用。

Objective：To study the effects of dexmedetomidine on the expression of Bcl-2, Bax and caspase-3 in hippocampal neurons cells of fetal rats incubated with propofol. Methods： Primary SD fetal rat hippo- campus neurons cells were generated with tissue fragment culture method, and 7th-day of cells were used for further experiments. The hippocampus neurons cells were diagnosed by NeuN, and were divided into 3 groups：the control group （group C）, the propofol group （group P, final concentration 100μmol/L）, and dexmedetomidine plus propofol group （group DP, final concentration 100μmol/L）. The cell apoptosis was assessed by flow cytometry. The mRNA and protein expression levels of Bcl-2, Bax and caspase-3 were de- tected by RT-PCR and western blotting, respectively. Results： The apoptosis rate in group P was higher than that in group C （ P 〈0.05）. The mRNA and protein expression levels of Bcl-2 were lower, while the caspase-3 mRNA level and active-caspase-3 expression level were higher in group P than those in group C （P 〈0. 05）. There was no statistical difference in the Bax expression between group P and group C （ P 〉0.05）, thus the Bcl-2/Bax ratio in group P was lower than that in group C （ P 〈0. 05）. Compared with group P, the cell apoptosis rate as well as the caspase-3 mRNA and active-caspase-3 protein levels were significantly decreased, whereas the mRNA and protein levels of Bcl-2 were notably increased in group DP （ P 〈0.05）. There was no statistical difference in the Bax expression between group P and group DP （ P〈0.05）, thus the Bcl-2/Bax ratio in group DP was higher than that in group P （ P 〈0.05）. Con- dusion.Dexmedetomidine could reduce apoptosis and protect the hippocampus neurons via up-regulating Bcl-2 expression and down-regulating caspase-3 expression.