丙泊酚对新生大鼠海马神经元形态结构及生长相关蛋白表达的影响

The effects of propofol anesthesia on the morphological structure of hippocampal neurons and the expres-sion of growth-related proteins in neonatal rats

目的：观察丙泊酚麻醉对新生大鼠海马神经元形态结构及生长相关蛋白表达的影响。方法雄性 SD 大鼠175只,日龄7 d,体重8-15 g,随机分为对照组（A 组）、丙泊酚25 mg/kg 组（B组）、丙泊酚50 mg/kg 组（C 组）、丙泊酚100 mg/kg 组（D 组）和丙泊酚200 mg/kg 组（E 组）,每组35只。A 组不注射任何药物,B、C、D 和 E 组分别腹腔注射丙泊酚25、50、100和200 mg/kg。每组取5只大鼠,于苏醒后即刻抽取动脉血样进行血气分析。各组其余大鼠又随机分成等份的两个亚组：A1和 A2组、B1和 B2组、C1和 C2组、D1和 D2组、E1和 E2组。A1、B1、C1、D1和 E1组大鼠于苏醒后2 h 用透射电镜观察海马神经元的形态学变化,采用半定量逆转录-聚合酶链反应（RT-PCR）和免疫印迹法（Western blot）检测海马脑源性神经营养因子（BDNF）、Bcl-2 mRNA 和蛋白的表达；A2、B2、C2、D2和 E2组大鼠苏醒后放回笼中继续饲养至9 w 时,再行上述相同实验。结果五组大鼠动脉血 pH 值、PaO2、PaCO2、碳酸氢根离子浓度（HCO-3）、剩余碱（BE）、SaO2差异无统计学意义。A1、A2、B1和 B2组大鼠海马神经元基本正常,C1、C2、D1和 D2组大鼠海马神经元细胞核肿胀、染色质减少,E1和 E2组大鼠海马神经元核碎裂、染色质边集甚至出现凋亡小体。与 A1组比较,B1、C1、D1和 E1组大鼠海马组织 BDNF mRNA、Bcl-2 mRNA、BDNF 蛋白和 Bcl-2蛋白表达均下调（P 〈0.05）；与 A2组比较,B2、C2、D2和 E2组大鼠海马组织 BDNF mRNA、Bcl-2 mRNA、BDNF 蛋白和 Bcl-2蛋白表达也均下调（P 〈0.05）。结论丙泊酚麻醉破坏海马神经元的形态结构,其机制可能与其抑制海马 BDNF、Bcl-2的表达有关。

Objective To investigate the effects of propofol anesthesia on the morphological structure of hippocampal neurons and the expression of growth-related proteins in neonatal rats. Methods One hundred and seventy-five 7-day-old male SD rats,weighing 8-1 5 g,were randomly di-vided into 5 groups （n=35 each）：control group （group A）,propofol groups received intraperitoneal （IP）propofol 25,50,100 and 200 mg/kg respectively （groups B,C,D and E）.Arterial blood sam-ples were obtained immediately after the animals were fully awake for blood gas analysis.The other rats in each group were randomly divided into two equal subgroups （groups A1 and A2,groups B1 and B2,groups C1 and C2,groups D1 and D2,groups E1 and E2 ）.The hippocampus of rats in groups A1,B1,C1,D1 and E1 were taken 2 h after the animals were fully awake.The ultrastructure of hippocampal neurons was observed by transmission electron microscope.Brain derived neurotrophic factor （BDNF）mRNA,Bcl-2 mRNA,BDNF protein and Bcl-2 protein in hippocampus were evalua-ted by semi-quantitative reverse transcription polymerase chain reaction （RT-PCR）and Western blot analysis.The rats in groups A2,B2,C2,D2 and E2 were raised up until 9-week-old and were taken the same experiments mentioned above.Results There was no significant difference in pH,PaO2 , PaCO2 ,HCO-3 ,BE and SaO2 among the 5 groups.The structure of hippocampal neurons was normal in groups A1,A2,B1 and B2.Nuclear blebbing and chromatin decreasing were observed in groups C1,C2,D1 and D2 while nuclear fragmentation,chromatin condensation and apoptotic bodies were observed in groups E1 and E2.Compared with that in group A1,BDNF mRNA,Bcl-2 mRNA,BD-NF protein and Bcl-2 protein were down-regulated in groups B1,C1,D1 and E1 （P 〈0.05）.Com-pared with that in group A2,BDNF mRNA,Bcl-2 mRNA,BDNF protein and Bcl-2 protein were also down-regulated in groups B2,C2,D2 and E2（P 〈0.05）.Conclusion Propofol may destroy the mor-phological structure of hippocampal neurons by down-regulating the expression of BDNF and Bcl-2.