利多卡因对大鼠脑损伤后脑组织水通道蛋白4表达的影响

背景:近年关于利多卡因脑保护作用的研究较多,但对创伤性脑水肿的治疗效果研究较少。水通道蛋白4在脑组织含量最高,并已证实水通道蛋白4参与了各种原因如脑创伤、脑梗死、脑肿瘤等所致的脑水肿形成。目的:观察利多卡因对实验大鼠脑损伤后水通道蛋白4的影响,分析利多卡因对脑水肿的治疗作用。设计:随机对照动物实验。单位:青岛大学医学院附属医院麻醉科。材料:实验于2004-01/07在青岛大学医学院附属医院脑病研究所完成。实验动物为3月龄健康雄性Wistar大鼠65只,随机数字表法分为3组,正常组5只,模型组和治疗组各30只,再分为脑损伤后1,4,6,12,24,48h6个时间点组,每个时间点各5只。方法:采用Feeney法建立右顶叶脑损伤动物模型,正常组仅做相应部位的手术致伤。大鼠于手术后2～8h均恢复饮食。治疗组大鼠分别于致伤后1,4,6,12,24,48h腹腔内注射利多卡因,每个时间点5只大鼠首次用量为30mg/kg,后维持用量15mg/kg,首次给药后每6h给药一次,共维持3d;模型组腹腔内注射30mg/kg生理盐水;正常组不给予特殊处理。脑损伤后5d采用干湿重法计算脑含水量。免疫组织化学法检测各组大鼠脑组织水通道蛋白4的表达(吸光度值)、光学显微镜下观察脑组织细胞形态学改变。主要观察指标:①各组大鼠的脑含水量。②各组大鼠脑组织水通道蛋白4的表达。③各组大鼠脑组织的病理学结果。结果:实验过程中无动物意外死亡或其他因素导致脱失,65只大鼠全部进入结果分析。①与模型组比较,大鼠脑损伤后6h之内给予利多卡因能显著降低脑组织含水量脑损伤后1h:(81.09±0.29)%,(83.04±0.25)%,P<0.05];脑损伤后4h:(81.34±0.35)%,(83.31±0.48)%,P<0.05];脑损伤后6h:(82.01±0.21)%,(83.25±0.37)%,P<0.05]。与模型组比较,治疗组脑损伤后1,4,6h水通道蛋白4的表达显著降低脑损伤后1h:(0.19±0.02),(0.24±0.03),P<0.05];脑损伤后4h:(0.21±0.05),(0.25±0.05),P<0.05];脑损伤后6h:(0.21±0.03),(0.24±0.02),P<0.05]。与模型组比较,脑损伤后12,24,48h给药,水通道蛋白4的表达和脑组织含水量差异无显著性意义(P>0.05)。②水通道蛋白4阳性细胞镜下呈空泡状,主要位于创伤周边的水肿区、创伤侧的皮质和血管周围及白质的星形胶质细胞、脉络丛、室管膜等处。③在创伤中心区细胞多表现出坏死,在损伤周围区,细胞多表现为凋亡,创伤后6h之内给予利多卡因治疗组坏死及凋亡细胞数较模型组明显减少。而创伤后12,24,48h给予利多卡因治疗组坏死及凋亡细胞数较模型组减少不明显。结论:大剂量利多卡因有减少大鼠脑损伤后水通道蛋白4的表达及减轻脑水肿的作用,但应在脑损伤后尽早用药。

Effect of lidocaine on the expression of aquaporin-4 in brain tissue of rats following brain injury

BACKGROUND: In recent years, there are many studies designed to explain the protective effect of lidocaine on brain, but few about the therapeutic effect on traumatic cerebral edema. The content of aquaporin-4(AQP-4) in brain tissue is the highest and it has been proved that AQP-4participants in the formation of cerebral edema induced by cerebral trauma, cerebral infarction, eerebrai tumor and other reasons.OBJECTIVE: To observe the effect of lidocaine on the expression of AQP-4 of experimental rats following brain injury and analyze the therapeutic effect of lidocaine on brain edema.DESIGN: A randomized and control animal experiment.SETTING: Department of Anesthesiology, Affiliated Hospital of Medical College of Qingdao University.MATERIALS: The experiment was carried out in the Institute of Brain Disease, the Medical School Hospital of Qingdao University between January and July 2004. Totally 65 three-month-old healthy male Wistar rats,were enrolled in the experiment and randomly divided into 3 groups: normal control group (n=5), model group (n=30) and treatment group (n=30). Thirty rats in the model group and treatment group were respectively assigned into 6 subgroups according to 6 different time points: 1,4,6,12,24 and 48 hours following brain injury, with 5 rats at each time point.METHODS: Animal models of brain injury at right parietal lobe were created according to the method from Feeney et al. As for the rats of normal control group, they only underwent operation to be injured at the corresponding part. Rats recovered the access to food and water 2 to 8 hours after operation. For the rats in the treatment group, they were intraperitoneally injected of lidocaine at the 1st, 4th,6th, 12th, 24th, and 48th hours following injury, 5 rats at each time point. The initial dosage was 30 mg/kg, then 15 mg/kg was maintained . Administration was conducted every 6 hours in 3 days; For the rats in the model group, they were intraperitoneally injected of 30 mg/kg normal saline and rats in the normal control group were given no special treatments. Water content of brain was calculated 5 days following brain injury with dry and wet weight method:water content of brain=brain mass (wet)-brain mass (dry)]/brain mass(wet)×100%. Expression of AQP-4 of brain tissue of rats was detected with immunohistochemical method and cytomorphological change of brain tissue was observed under optical microscope.MAIN OUTCOME MEASURES: ① Water content of brain of rats in each group. ② Expression of AQP-4 of brain tissue of rats in each group.③ Pathological results of brain tissue of rats in each group.RESULTS: No rats died accidentally or for other factors in the process of experiment, finally, all the 65 rats entered the stage of result analysis. ①Compared with model group, administration of lidocaine within 6 hours following brain injury could significantly decrease the water content of brain tissue 1 hour after brain injury: (81.09±0.29)%, (83.04±0.25)% ,P ＜ 0.05];4 hours after brain injury: (81.34±0.35)%, (83.31±0.48)%,P ＜ 0.05] ;6 hours after brain injury: (82.01±0.21)%, (83.25±0.37)% ,P ＜ 0.05]. Compared with model group, administration of lidocaine could significantly decrease the expression of AQP-4 1 hour after brain injury:(0.19±0.02), (0.24±0.03),P ＜ 0.05]; 4 hours after brain injury: (0.21±0.05 ), (0.25±0.05) ,P ＜ 0.05]; 6 hours after brain injury: (0.21±0.03 ),(0.24±0.02) ,P ＜ 0.05]. There were no significant differences of AQP-4expression and water content of brain tissue when administration was conducted at the 12th, 24th and 48th hours following brain injury (P ＞ 0.05). ②Under the microscope, AQP-4 positive cells presented vacuolus, they mainly lay in the edema area of peripheral part of trauma, cortex of traumatic side and around the blood vessel as well as astrocyte of white substance, choroid plexus and ependymal layer. ③ Necrosis was found in most cells in the central area of trauma and apoptosis in most cells in the peripheral area. Compared with model group, necrotic and apoptotic cells were significantly less within 6 hours following trauma, but not at the 12th,24th and 48th hours following trauma in the treatment group.CONCLUSION: High dosage of lidocaine can decrease the expression of AQP-4 and lighten cerebral edema following brain injury, but administration should be given as early as possible.