Development of the treatment for neonatal for hypoxia-ischemia (HI) brain injury

炎症是缺氧缺血性脑损伤的重要因素。白细胞介素(IL)-18是一种促炎细胞因子，可能是HI后未成熟脑损伤的一个因素。为了研究hi后低温对发育中的大鼠脑IL-18的影响，将7日龄大鼠进行左颈动脉结扎后8%供氧60 min，并分为低温组（直肠温度32℃，24 h）和常温组（36℃，24 h）。正常体温组同侧半球IL-18 mRNA水平在HI后24 h和72 h均较对照组显著升高，而低温组同侧半球IL-18 mRNA水平在两个时间点均较正常体温组显著降低。与正常体温组相比，低温组同侧半球IL-18蛋白水平在HI后72 h显著升高，而与正常体温组相比，低温组IL-18蛋白水平显著降低。高温后72 h，正常体温组同侧半脑皮层、胼胝体和纹状体均可见il -18阳性细胞，而低温组几乎未见il -18阳性细胞。双标记免疫染色发现大多数il -18阳性细胞与凝集素共定位，凝集素是小胶质细胞的标记物。正常体温组皮质区和CC区变形虫小胶质细胞（AM）数量显著高于对照组，但分支小胶质细胞（RM）数量极少。相比之下，与常温组相比，低温组皮质和CC区AM的数量明显减少，而与对照组相比，低温组AM和RM的数量无显著差异。综上所述，我们发现高温低温后IL-18 mRNA和蛋白水平降低，高温低温后可能降低发育中的大脑小胶质细胞的激活。为了探讨高碳酸血症对新生儿缺氧缺血性脑损伤的长期影响，我们在新生大鼠缺氧缺血模型中检验了高碳酸血症的作用。将大鼠单侧颈动脉结扎，暴露于8%的氧气中30分钟。新生大鼠单侧缺氧缺血时给予6%的二氧化碳，3个月后观察运动功能和神经功能的变化。根据蒙托亚阶梯试验，在高碳酸动物中观察到明显的运动功能改善。高碳酸血症小鼠单侧脑损伤明显改善，且与运动功能表现密切相关。激光多普勒血流仪监测低氧缺血时的脑血流，高碳酸血症动物的脑血流得到较好的保存。我们的研究结果表明，缺氧缺血时的轻度高碳酸血症可能通过增加缺氧时的脑血流量，为未成熟的大脑提供持久的运动功能和神经保护。低温治疗不仅是成人，而且是新生儿脑缺氧缺血性损伤的一种潜在治疗方法。然而，在大量神经发生的发育中，低温对大脑的副作用尚不清楚。研究了胸苷类似物5-溴脱氧尿苷（BrdU）在低温环境下对新生大鼠神经祖细胞增殖的影响。大鼠幼崽被分为两组，低温组（30℃）和常温组（37℃）。在每种环境下放置21 h后，腹腔注射BrdU标记分裂细胞，24 h后处死幼鼠。我们检测了脑室周围室下区和齿状回颗粒下区BrdU标记细胞的数量。在低温环境下，brdu标记的细胞在齿状回的数量明显减少，但在心室周围区域没有。因此，严重低温环境导致新生大鼠神经发生减少。这些观察结果对于围产期脑缺氧缺血性损伤后的临床低温治疗值得注意。少

Inflammation is an important factor for hypoxia-ischemia (HI) brain injury. Interleukin (IL)-18 is a proinflammatory cytokine which may be a contributor to injury in the immature brain after HI. To investigate the effects of post-HI hypothermia on IL-18 in the developing brain, 7-day-old rats were subjected to left carotid artery ligation followed by 8% oxygen for 60 min and divided into a hypothermia group (rectal temperature 32 degrees C for 24 h) and a normothermia group (36 degrees C for 24 h). The significant increase of the IL-18 mRNA was observed in the ipsilateral hemispheres of the normothermia group at 24 h and 72 h after HI compared with controls, but the level in the ipsilateral hemispheres of the hypothermia group was significantly reduced at both time points, compared with the normothermia group, respectively. The IL-18 protein level in the ipsilateral hemispheres of the normothermia group significantly increased at 72 h after HI compared with controls, however, the prote … More in level of the hypothermia group was significantly decreased, compared with the normothermia group. IL-18-positive cells were observed throughout the entire cortex, corpus callosum (CC) and striatum in the ipsilateral hemispheres of normothermia group at 72 h after HI, however, little positive cells were observed in the hypothermia group. Double labeling immunostaining found that most of the IL-18-positive cells were colocalized with lectin, which is a marker of microglia. The number of ameboid microglia (AM) in the normothermia group was significantly increased in cortex and CC, compared with the number in controls, but there were very few ramified microglia (RM) in these areas. In contrast, the number of AM in the hypothermia group was significantly decreased in cortex and CC, compared with the number in the normothermia group, and there were no significant differences in the number of AM and RM between the hypothermia group and controls. In conclusion, we found that IL-18 mRNA and the protein level were attenuated by post-HI hypothermia and that post-HI hypothermia may decrease microglia activation in the developing brain.This study was undertaken to investigate the long-term effect of hypercapnia on neonatal hypoxic-ischemic brain injury, we tested its effect in a neonatal rat hypoxia-ischemia model. The rats were subjected to unilateral carotid artery ligation and exposure to 8% oxygen for 30 minutes. Six percent carbon dioxide was administered to the neonatal rats during unilateral hypoxia-ischemia, and the motor function and neurologic outcomes were determined 3 months later. Significant motor functional improvement was observed in the hypercapnic animals, as judged by the Montoya staircase test. The unilateral brain injury was significantly ameliorated in the hypercapnic animals, and this amelioration was well correlated with the motor functional performance. Cerebral blood flow during hypoxia-ischemia, monitored by laser Doppler flowmetry, was better preserved in the hypercapnic animals. Our results suggest that mild hypercapnia during hypoxia-ischemia may provide long-lasting motor functional as well as neurologic protection for immature brains, possibly by increasing cerebral blood flow during hypoxia.Hypothermia is a potential therapy for cerebral hypoxic ischemic injury of not only adults but also neonates. However, the side effects of hypothermia in the developing brain, where a massive amount of neurogenesis occurs, remain unclear. We investigated the proliferation of neural progenitor cells by systemic application of the thymidine analog 5-bromodeoxyuridine (BrdU) in neonatal rats in a severe hypothermic environment. The rat pups were divided into two groups, a hypothermia group (30 degrees C) and a normothermia group (37 degrees C). After the pups were placed for 21 h in each environment, BrdU was injected intraperitoneally to label dividing cells, and then the pups were sacrificed at 24 h. We examined the number of BrdU-labeled cells in the subventricular zone of the periventricle and the subgranular zone of the dentate gyrus. In the hypothermic environment, BrdU-labeled cells significantly decreased in number in the dentate gyrus, but not in the periventricular region. Thus, the severe hypothermic environment induced a decrease of neurogenesis in the neonatal rat. These observations are noteworthy regarding clinical hypothermia therapy following cerebral hypoxic ischemic injury during the perinatal period. Less