亚低温干预对大鼠颅脑创伤后钙调蛋白表达和脑水肿的影响

Effects of mild hypothermia on calmodulin expression and brain edema in the brain tissue of rats with traumatic brain injury

目的亚低温治疗颅脑创伤是针对颅脑创伤有效的脑保护措施。文中旨在探讨亚低温干预对大鼠颅脑创伤模型钙调蛋白表达和脑水肿的影响。方法选取90只成年SD大鼠,随机分为假手术组(37℃,仅开骨窗,不打击)、常温组(37℃,开骨窗后打击制作颅脑创伤模型)及亚低温组[(32±0.5)℃,开骨窗后打击制作颅脑创伤模型],每组30只。每组各取6只大鼠于1、3、5、7d行改良神经功能评分(mNSS),其余分别于6、12、24、48h行头颅MRI后取脑组织,分别采用荧光定量PCR、免疫组化和Western-blot检测各组大鼠脑组织中钙调蛋白基因转录和蛋白表达情况。结果亚低温组、常温组各时间点mNSS评分较假手术组明显升高(P<0.05);亚低温组较常温组明显降低(P<0.05)。亚低温组6、12、24h钙调蛋白mRNA(1.83±0.19、1.72±0.12、1.59±0.06)较常温组(2.76±0.25、2.49±0.18、2.04±0.14)表达减少(P<0.05),亚低温组48h钙调蛋白mRNA(1.60±0.07)较常温组(1.65±0.09)差异无统计学意义。亚低温组、常温组各时间点钙调蛋白、钙调蛋白mRNA表达较假手术组明显上调(P<0.05),亚低温组蛋白表达较常温组下降(P<0.05)。亚低温组6、12、24、48h脑组织损伤水肿区体积[(32.14±4.52)、(36.52±4.10)、(42.10±4.38)、(46.25±5.02)mm^3]较常温组[(48.56±5.35)、(53.13±6.31)、(59.23±6.82)、(62.35±7.25)mm^3]明显降低(P<0.05)。结论亚低温干预治疗能改善颅脑创伤后大鼠神经功能,明显降低大鼠颅脑创伤后的钙调蛋白表达和脑水肿,可能与亚低温的神经保护机制有关。

Objective Mild hypothermia (MHT) can effectively protect the brain in traumatic brain injury (TBI). This study was to investigate the effects of MHT on the calmodulin (CAM) expression and brain edema in the rat model of TBI. Methods Ninety adult SD rats were randomly divided into a sham operation, a normal temperature and an MHT group of equal number. Immediately after TBI, the rats of the MHT group maintained at a rectal temperature of (32 ± 0.5)°C for 6 hours. Modified neurological severity scores (mNSS) were obtained from 6 rats in each group at 1, 3, 5 and 7 days after modeling, and the rest of the animals subjected to brain MRI at 6, 12, 24 and 48 hours and then killed for determination of the CAM gene transcription and protein expression in the brain tissue by real-time PCR, immunohistochemistry and Western blot. Results The mNSSs were significantly higher in the MHT and normal temperature groups than in the sham operation control (P < 0.05) at all time points, neurological severity markedly decreased in the MHT group compared with the normal temperature group (P < 0.05). At 6, 12, 24 and 48 hours, the expression of CAM mRNA was remarkably down-regulated in the MHT group (1.83 ± 0.19, 1.72 ± 0.12, 1.59 ± 0.06 and 1.60 ± 0.07) in comparison with the normal temperature group (2.76 ± 0.25, 2.49 ± 0.18, 2.04 ± 0.14 and 1.65 ± 0.09)(P < 0.05), even lower in the MHT than in the normal temperature group (P < 0.05), but higher in both of the two groups than in the sham operation group (P < 0.05). At 6, 12, 24 and 48 hours, the volume of brain edema was significantly reduced in the MHT group ([32.14 ± 4.52],[36.52 ± 4.10],[42.10 ± 4.38] and [46.25 ± 5.02] mm^3) as compared with the normal temperature group ([48.56 ± 5.35],[53.13 ± 6.31],[59.23 ± 6.82] and [62.35 ± 7.25] mm^3)(P < 0.05). Conclusion Mild hypothermia can improve the neurological function and reduce the CAM expression and brain edema in the brain tissue of rats with traumatic brain injury, which may be related to the neuroprotective effect of mild hypothermia.