异丙酚后处理对大鼠脑外伤后AQP-4表达及神经元凋亡的影响

EFFECT OF PROPOFOL POST-TREATMENT ON AQUAPORIN-4 EXPRESSION AND NEURONAL APOPTOSIS AFTER BRAIN TRAUMA IN RATS

目的观察异丙酚对大鼠脑外伤后水通道蛋白-4(AQP-4)表达及神经元凋亡的影响,探讨异丙酚减轻脑外伤的作用机制。方法健康雄性Wistar大鼠150只,随机分为对照组和异丙酚组,每组75只大鼠。按Feeney方法建立自由落体脑损伤大鼠模型,异丙酚组大鼠致伤后1h后经尾静脉注入10g/L异丙酚10 mg/kg后,以微量泵按30mg/(kg·h)持续输注异丙酚2h。对照组致伤后1h经尾静脉注射同体积生理盐水后,以微量泵持续输注同体积生理盐水2h。两组分别在伤后6、12、24、48和72h随机各处死5只大鼠,应用干湿质量法测定大鼠大脑半球含水量。剩余的50只大鼠在每个时间点随机抽取10只大鼠经心脏灌注后取脑组织制作石蜡切片,苏木精-伊红(HE)染色观察脑组织损伤情况及周边区神经元形态变化,采用TUNEL法检测脑组织中凋亡神经元数以及AQP-4阳性细胞数。结果异丙酚组各时间点脑含水量较对照组明显下降(F=4.12~6.25,P<0.05)。对照组大鼠脑组织切片HE染色显示,创伤区可以见到细胞间以及血管周围间隙增大,伴有神经胶质细胞和神经元崩解、坏死;在损伤相邻区域的神经元细胞体和血管内皮细胞肿胀,局部可见到红细胞渗出和炎性细胞聚集。异丙酚组相应区域上述病理学改变明显减轻,与对照组比较,坏死及凋亡细胞明显减少。异丙酚组相应时间点AQP-4阳性细胞数及凋亡神经元数与对照组比较,明显减少(F=4.02~9.56,P<0.05),其中AQP-4阳性细胞数伤后12、24h时减少更为明显(P<0.05),凋亡神经元伤后24、48h减少最为明显(P<0.05)。结论异丙酚可减少大鼠脑外伤后AQP-4的表达及神经元的凋亡,减轻脑损伤。

Objective To investigate the effect of propofol on aquaporin-4（AQP-4）expression and neuronal apoptosis after brain trauma in rats,as well as the mechanism of action of propofol in alleviating brain trauma. Methods A total of 150 healthy male Wistar rats were randomly divided into control group and propofol group,with 75 rats in each group.The Feeney method was used to establish a rat model of brain injury caused by free fall.The rats in the propofol group were given tail vein injection of 10g/L propofol at a dose of 10mg/kg at 1hafter injury,followed by micropump injection of propofol at a dose of 30mg/（kg·h）for 2h.The rats in the control group were given tail vein injection of an equal volume of normal saline at 1hafter injury,followed by micropump injection of an equal volume of normal saline for 2h.Five rats each were randomly sacrificed at 6,12,24,48,and 72 hafter injury,and the dry-wet weight method was used to measure the water content in the hemisphere.Ten rats were randomly selected at each time point and were treated with cardiac perfusion to collect brain tissue and prepare paraffin section;HE staining was used to observe the injury of brain tissue and the morphological changes of surrounding neurons,and TUNEL was used to measure the numbers of apoptotic neurons and AQP-4-positive cells in brain tissue. Results Compared with the control group,the propofol group had a significant reduction in cerebral water content at each time point（F=4.12-6.25,P〈0.05）.As was shown by HE staining of brain tissue sections,the control group had increased intercellular space and perivascular space with disintegration and necrosis of glial cells and neurons in the area of brain trauma,swollen neuronal cell bodies and vascular endothelial cells in the adjacent area,and erythrocyte diapedesis and aggregation of inflammatory cells in some areas;compared with the control group,the propofol group had significant alleviation in these pathological changes and significant reductions in the numbers of necrotic and apoptotic cells.Compared with the control group,the propofol group had significant reductions in the numbers of AQP-4-positive cells and apoptotic neurons at each time point（F=4.02-9.56,P〈0.05）;the propofol group had a significantly greater reduction in the number of AQP-4-positive cells at 12and24 hafter injury（P 〈0.05）,as well as a significantly greater reduction in the number of apoptotic neurons at 24 and 48hafter injury（P〈0.05）. Conclusion Propofol can downregulate the ex-pression of AQP-4,reduce neuronal apoptosis after brain trauma,and thus alleviate brain injury.