早期高压氧治疗对缺氧缺血性脑损伤新生大鼠的远期保护作用

Long-term effects of early hyperbaric oxygen therapy on neonatal rats with hypoxic-ischemic brain damage

摘要:

目的：高压氧(hyperbaricoxygen,HBO)在缺氧缺血性脑损伤(hypoxic-ischemicbraindamage,HIBD)中的应用及疗效仍存在争议。至目前为止,HBO在新生动物HIBD中的实验研究不多,这些实验注重近期病理和生化结果的评价,缺乏远期功能评价指标。该实验评价早期HBO治疗对HIBD新生大鼠远期脑病理和行为的影响。方法：7日龄大鼠随机分为对照组(n=18)、HIBD组(n=17)和HBO组(n=17,HIBD后0.5~1h开始2个绝对大气压HBO治疗,稳压30min/次,每日1次,共2d),以大鼠37~41日龄的学习记忆功能(Morris水迷宫实验)和42日龄的脑形态组织学(脑重量、海马CA1区存活神经元数、AchE纤维面积和NOS神经元数)来判断干预效果。结果：HIBD组学习记忆功能严重不良伴有脑形态组织学的明显缺损,与对照组比较水迷宫实验的平均逃逸潜伏期(EL)延长(56.35±22.37svs23.07±16.28s);搜索时间和搜索距离缩短(29.29±6.06svs51.21±4.59s)和(548±92cmvs989±101cm),左脑重量减轻(0.601±0.59gvs0.984±0.18g);CA1区存活神经元数减少(100±27个/mmvs183±8个/mm);AchE纤维面积减少(18.50±2.24)%vs(27.50±2.18)%,NOS神经元数减少(19.25±4.33个/mm2vs33.75±5.57个/mm2)以上两组比较均P<0.05。HBO组学习记忆功能不良改善,脑形态组织学缺损减轻,与对照组比较差异有显著性,EL为39.17±21.20s;搜索时间为36.84±4.36s;搜索距离686±76cm;脑重量0.768±0.85g;存活神经元数133±25个/mm;AchE纤维面积(21.94±2.73)%(均P<0.05)。结论：早期HBO治疗在一定程度上改善了HIBD所引起的学习记忆功能不良并减轻了HIBD所导致的远期脑形态组织学缺损。

Abstract:

OBJECTIVE: The application and therapeutic effect of hyperbaric oxygen (HBO) in hypoxic-ischemic brain damage (HIBD) remains controversial. Previous studies have focused on the early pathological and biochemical outcomes and there is a lack of long-term functional evaluation. This study was designed to evaluate the long-term pathological and behavioral changes of early HBO therapy on neonatal rats with HIBD. METHODS: Postnatal 7 days (PD7) rat pups were randomly assigned into Control (n=18), HIBD (n=17) and HBO treatment groups (n=17). HIBD was induced by ligating the left common carotid, followed by 2 hrs hypoxia exposure in the HIBD and HBO treatment groups. The Control group was sham-operated and was not subjected to hypoxia exposure. The HBO therapy with 2 atmosphere absolutes began 0.5-1 hr after HIBD in the HIBD treatment group, once daily for 2 days. The spatial learning and memory ability were evaluated by the Morris water maze test at PD37 to PD41. The morphological and histological changes of the brain, including brain weight, survival neurons, AchE positive unit and NOS positive neurons in hippocampal CA1 region, were detected at PD42. RESULTS: The rats in the HIBD group displayed significant morphological and histological deficits, as well as severe spatial learning and memory disability. In the Morris water maze test, the mean escape latency were longer (56.35±22.37 s vs 23.07±16.28 s; P<0.05) and the probe time and probe length were shorter in the HIBD group (29.29±6.06 s vs 51.21±4.59 s and 548±92 cm vs 989±101 cm; both P<0.05) compared with the Control group. The left brain weight in the HIBD group was lighter than that in the Control group (0.601±0.59 g vs 0.984±0.18 g; P<0.05 ). The survival neurons in the hippocampal CA1 region were less (100±27/mm vs 183±8/mm; P<0.05), as well as the AchE-positive unit and NOS-positive neurons (18.50±2.24% vs 27.50±2.18% and 19.25±4.33 vs 33.75±5.57 respectively; P<0.05) after HIBD. Early HBO treatment improved the abilities of spatial learning and alleviated the morphological and histological damage. The mean escape latency (39.17±21.20 s) was shortened, the probe time (36.84±4.36 s) and the probe length (686±76 cm) were longer, and the brain weight (0.768±0.85 g), the survival neurons (133±25/mm) and the AchE-positive unit (21.94±2.73%) increased significantly compared with those of the HIBD group (P<0.05). CONCLUSIONS: Early HBO treatment resulted in a protective effect against HIBD-induced long-term brain morphological and histological deficits and spatial learning and memory disability.