Wang Xiao-Yang, Zhu Chang-Lian, Xu Fa-Lin, Cheng Xiu-Yong, Qiu Lin, Hu Sheng-Hai
Department of Pediatrics, Third Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China.
Zhongguo Dang Dai Er Ke Za Zhi. 2006 Aug;8(4):315-8.
The study was to investigate the effect of different temperatures during hypoxia on brain injury in mice of different ages.
Newborn C57/BL6 mice at 7 days or 21 days of life were subjected to left carotid artery ligation followed by exposure with 10% oxygen. The mice were kept in a incubator with a predetermined, constant temperature, either 34 degrees centigrade (Hypothermia group) or 36 degrees centigrade (Normothermia group). Brain injury was evaluated 7 days after hypoxia-ischemia (HI). Active caspase-3 and apoptosis-inducing factor (AIF) expressions in the brain tissue were detected by immunohistochemistry and Western Blot was used to evaluate the phosphor-Akt (P-Akt) expression in the brain tissue at 24 hrs post-HI.
Brain injuries, including the cortex, hippocampus, striatum and thalamus injuries, occurred in the Normothermia group at 7 days post-HI. The brain cortex showed cystic cavitation in the postnatal day (P)7 pups mice and laminar infarct of the brain cortex was observed in P21 mice. In the Hypothermia group, the P7 mice did not present with laminar infarct of the cortex and had lower scores of neuropathological lesions in cortex, hippocampus, striatum and thalamus than P7 mice from the Normothermia group (P < 0.01); the cortex injuries were significantly relieved but the injuries of hippocampus, striatum and thalamus in P21 mice were similar to those from the Normothermia group. Active caspase-3 (7.0 +/- 5.6) and AIF positive cells (3.7 +/- 6.2) in the cortex of P7 mice from the Hypothermia group were significantly lower than those of the Normothermia group (51.5 +/- 23.2 and 31.8 +/- 22.4) at 24 hrs post-HI (P < 0.01). Wetstern Blot showed the P-Akt expression was obviously decreased in the ipsilateral hemisphere to the occlusion compared with that of the contralateral hemisphere after HI in the Normothermia group (P < 0.05), while in the Hypothermia group the P-Akt expression was not significantly different between the two hemispheres.
Hypothermia has protective effects against HI insults. The protection was more pronounced for the immature brain than the mature brain.
本研究旨在探讨缺氧期间不同温度对不同年龄小鼠脑损伤的影响。
将出生7天或21天的新生C57/BL6小鼠进行左颈动脉结扎，然后暴露于10%氧气环境中。将小鼠置于预先设定的恒温培养箱中，温度为34摄氏度（低温组）或36摄氏度（正常体温组）。在缺氧缺血（HI）7天后评估脑损伤情况。通过免疫组织化学检测脑组织中活化的半胱天冬酶-3（active caspase-3）和凋亡诱导因子（AIF）的表达，并在HI后24小时使用蛋白质免疫印迹法评估脑组织中磷酸化Akt（P-Akt）的表达。
正常体温组在HI后7天出现脑损伤，包括皮质、海马、纹状体和丘脑损伤。出生后第7天（P7）的幼鼠脑皮质出现囊性空洞，P21小鼠观察到脑皮质层状梗死。在低温组中，P7小鼠未出现皮质层状梗死，且皮质、海马、纹状体和丘脑的神经病理损伤评分低于正常体温组的P7小鼠（P<0.01）；P21小鼠的皮质损伤明显减轻，但海马、纹状体和丘脑的损伤与正常体温组相似。低温组P7小鼠皮质中活化的半胱天冬酶-3（7.0±5.6）和AIF阳性细胞（3.7±6.2）在HI后24小时明显低于正常体温组（51.5±23.2和31.8±22.4）（P<0.01）。蛋白质免疫印迹显示，正常体温组HI后，与对侧半球相比，结扎同侧半球的P-Akt表达明显降低（P<0.05），而低温组两侧半球的P-Akt表达无明显差异。
低温对HI损伤具有保护作用。对未成熟脑的保护作用比对成熟脑更明显。
