甲苯暴露嗅觉印迹对小鼠行为学的影响

Observation of Toluene Olfactory Imprinting on the Ethology of Mice

[目的]探索小鼠甲苯嗅觉印迹的产生及新生期处于单一负性气味环境中小鼠成年后的行为学改变。[方法]将70天龄的5对昆明小鼠配种,成功受孕的4只孕鼠单笼饲养;根据母鼠所产仔鼠按窝分为3个暴露组、1个对照组。暴露组仔鼠在出生后连同母鼠一起,立即放置于低浓度甲苯气味的密闭箱中,分别是甲苯连续吸入1周、2周、3周记为暴露1组、暴露2组、暴露3组;染毒期满后将小鼠移至空气通风的环境中饲养。对照组仔鼠在出生后与其母鼠共同置于通风处,呼吸空气。小鼠6周龄时,进行下列实验:嗅觉识别实验、嗅觉辨别实验、六臂早迷宫实验和Morris水迷宫实验。[结果]与对照组相比,3组暴露小鼠能很快识别出甲苯并对其形成偏爱,在甲苯吸入2周的动物最为明显(P<0.05);暴露鼠对甲苯分辨力增强的同时对其他气味的分辨力明显减弱(P<0.05);在迷宫实验中,暴露鼠的空间学习和记忆能力下降(P<0.05)。[结论]新生期处于甲苯气味环境中的小鼠能对甲苯产生嗅觉印迹;在对这种单一气味的敏感性增加的同时,抑制了对其他气味的分辨能力并导致其空间学习和记忆能力下降。这提示:生命早期单一的负性气味环境可以影响脑的正常发育。

[ Objective ] To explore the.formation of toluene olfactory imprinting of mice and the behavior changes of adult mice having placed in a single negative odor environment in their early life. [ Methods ] 5 pairs Kunming mice at 70 d of age were mated. 4 female mice got pregnant successfully. Pregnant mice were raised in separate cages. Blank control pups were put in a good ventilation place to breathe wholesome air. Other pups with their mother were put in a cabinet filled with low concentration of toluene vapour immediately after their born. These pups were respectively grouped as continuous inhalation of toluene for 1 w, 2 w, and 3 w. At the terminal of preset time, all mice were removed and raised in fresh air. At the age of 6 weeks, experiments of olfactory reeognization test, olfactory discrimination test, six-arm dry maze test and Morris water maze test were arranged for all pups. [ Results ] Compared with blank control group, all experimental mice showed enhanced recognization ability for toluene, and formed preference for it, especially in the mice inhaled of toluene for 2 w（ P 〈 0.05 ）. At the same time, discrimination ability for other odors was attenuated（ P 〈 0.05 ）. In the maze tests, for experimental mice, the ability of study and memory for space was decreased （ P 〈 0.05 ）. [ Conclusion ] Mouse, whose early life was spent in toluene odor environment, would form olfactory imprinting for toluene. Its sensitivity to the single odor would be increased, meanwhile its discrimination for other odors would be decreased and the ability of study and memory for space would be attenuated. This indicates that the single and negative odor environment in the early life influences the normal development of the brain.