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中海拔低氧环境适应缓解小鼠胚胎期急性低氧造成的发育和认知损伤

刘慧浪, 孙永梅, 李传玉, 牛海晨, 苏敏, 王京昆

云南省药物研究所，云南白药集团股份有限公司创新研发中心，云南省中药和民族药新药创制企业重点实验室，昆明 650111；阿姆斯特丹自由大学分子和细胞神经生物学系，神经基因组学和认知研究中心，阿姆斯特丹 1081HV，荷兰；昆明理工大学灵长类转化医学研究院，昆明 650500；徐州医科大学遗传学系，徐州 221004

摘要

胚胎期急性严重低氧常导致出生后运动失调、认知功能障碍和精神发育异常，目前仍缺乏有效的预防治疗手段。本研究旨在探讨以世代为单位的中海拔低氧环境适应是否对胚胎期急性严重低氧处理的小鼠有保护效应。以在昆明(海拔约1 900 m)饲养繁殖一年半，传代6~7代的ICR小鼠为研究对象，在妊娠9天(gestation day 9, GD 9)、13天(GD 13)或17天(GD 17)对孕鼠施加急性低氧处理(7% O2, 6 h)，测试仔鼠出生后的发育情况、运动(旷场)、空间学习记忆(水迷宫)和焦虑水平(高架十字迷宫)，并对相关脑区进行细胞计数。此外，还检测了生活在中海拔和低海拔地区小鼠的血液学指标。结果显示：(1) 中海拔低氧环境适应良好的小鼠，其血液中的红细胞计数(red blood corpuscle count, RBC)、血红蛋白浓度(hemoglobin concentration, HBC)、红细胞压积(hematocrit, HCT)水平显著高于低海拔地区同性别的小鼠；(2) 低氧组仔鼠的空间学习记忆能力没有损伤，并且GD 17组雌性仔鼠的空间记忆提取能力强于对照组；(3) 低氧各组仔鼠均未见外观畸形和运动能力受损；(4) 胚胎期低氧未造成仔鼠伏隔核、杏仁核和海马神经元发生明显坏死。以上结果提示中海拔低氧环境适应良好的小鼠遭遇胚胎期急性严重低氧时，其发育、运动和认知功能障碍程度明显轻于低海拔地区小鼠的，其保护机制可能是：经过数代中海拔低氧环境适应，ICR小鼠血液中的HBC和HCT增加。本研究的这些新发现可能会为探讨急性胚胎期低氧损伤作用和干预疗法提供依据。

关键词： 低氧环境适应; 神经保护作用 ; 急性胚胎期低氧 ; 发育障碍 ; 认知障碍

分类号：R339.3

Acclimatization to middle altitude hypoxia protects against developmental and cognitive deficits caused by acute fetal hypoxia in mice

LIU Hui-Lang, SUN Yong-Mei, LI Chuan-Yu, NIU Hai-Chen, SU Min, WANG Jing-Kun

Yunnan Institute of Materia Medica, Innovation and R&；D Center of Yunnan Baiyao Group Co., Ltd., Yunnan Province Company Key Laboratory for TCM and Ethnic Drug of New Drug Creation, Kunming 650111, China； Department of Molecular and Cellular Neurobiology, Center for Neurogenomics &； Cognitive Research, VU University Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, Netherlands； Institute of Primate Translational Medicine, Kunming University of Science and Technology, Kunming 650500, China； Department of Genetics, Xuzhou Medical University, Xuzhou 221004, China

Abstract

Acute fetal hypoxia (AFH) can elicit postnatal motor deficits and cognitive impairments. To test whether lifelong acclimatization to middle altitude (MA) hypoxia has protective effects on the impairments caused by AFH, ICR mice bred at 1 900 m altitude for 6–7 generations were evaluated under AFH. On gestation day 9 (GD 9), 13 (GD 13) or 17 (GD 17), pregnant mice received a single exposure to acute hypoxia (7% O2, 6 h). Physiological and neurodevelopmental behaviors, motor function (open field), spatial learning and memory (Morris water maze), and anxiety level (elevated plus maze) were examined in the offspring from neonate to adulthood. In the neonatal age, among all the physiological and behavioral landmarks, almost no differences were found in the hypoxia groups. In the juvenile period, no obvious impairments of motor function and anxiety level were found in the hypoxia groups. In the adult period, no obvious impairment of motor function was found in hypoxia groups; Interestingly, AFH groups’ offspring showed normal or enhanced long-term spatial memory ability after AFH. These data suggest that AFH cause little abnormalities in the offspring of MA-adapted mice. To further investigate the underlying mechanisms, the neuronal numbers in behavior-related brain areas (accumbens nucleus, basal amygdala and hippocampus) were counted, and the physiological parameters of the blood were measured. The morphological data showed that no obvious neuronal necrosis was found in all hypoxia groups. In addition, blood tests showed that red blood corpuscle count, hemoglobin concentration and hematocrit levels in mice raised at MA were markedly higher in both males and females, compared with controls raised at the sea level. These data suggest that lifelong acclimatization to MA hypoxia has protective effects against development delay, motor deficits and spatial learning and memory impairments induced by AFH, and the protective effects may be due to higher hemoglobin concentration and hematocrit levels in the blood. The findings may provide a better understanding of fetal hypoxia and potential intervention treatments.

Key words: hypoxia acclimatization; neuroprotective function ; acute fetal hypoxia ; developmental disorder ; cognitive disorder

收稿日期：2016-11-05　　录用日期：2016-12-31

通讯作者：刘慧浪　　E-mail: liuhuilang@163.com

引用本文：

刘慧浪, 孙永梅, 李传玉, 牛海晨, 苏敏, 王京昆. 中海拔低氧环境适应缓解小鼠胚胎期急性低氧造成的发育和认知损伤[J]. 生理学报 2017; 69 (2): 146-158.

LIU Hui-Lang, SUN Yong-Mei, LI Chuan-Yu, NIU Hai-Chen, SU Min, WANG Jing-Kun. Acclimatization to middle altitude hypoxia protects against developmental and cognitive deficits caused by acute fetal hypoxia in mice. Acta Physiol Sin 2017; 69 (2): 146-158