Mundorf Annakarina, Matsui Hiroshi, Ocklenburg Sebastian, Freund Nadja
Division of Experimental and Molecular Psychiatry, Department of Psychiatry, Psychotherapy and Preventive Medicine, LWL University Hospital, Ruhr-University Bochum, Germany.
Institute of Cognitive Neuroscience, Department Biopsychology, Ruhr University Bochum, Germany.
Behav Brain Res. 2020 Sep 1;393:112807. doi: 10.1016/j.bbr.2020.112807. Epub 2020 Jul 13.
Atypical leftward behavioral asymmetries have been associated with early life stress and psychopathologies in humans and animals. Maternal separation (MS) is a frequently used model to investigate early life stress and psychopathologies but has not yet been studied in terms of asymmetries. This study aims to investigate whether prolonged MS induces atypical leftward asymmetries in the turning behavior of rats. MS was performed from postnatal days 2-20 followed by a second stressor from postnatal days 21-40. Asymmetry of turning behavior was then examined in the elevated plus-maze test upon weaning (juveniles and dams) or adolescence. The number of left and right turns was calculated per animal using the deep learning software package DeepLabCut enabling markerless pose estimation. Then, a lateralization quotient (LQ) was determined for each animal allowing to investigate the strength as well as the preferred side of asymmetry. LQ analysis revealed a significant leftward asymmetry in the prolonged stress group. Moreover, analyzing the number of turns revealed significantly more left than right turns in total in this group. Control animals showed no asymmetries in turning behavior. These results indicate that prolonged stress during the early postnatal days led to atypical leftward turning behavior. The stress-induced atypical asymmetry might be a mediator of early life stress and the development of psychiatric disorders.
非典型的行为左向不对称与人类和动物的早期生活应激及精神病理学有关。母婴分离（MS）是一种常用的研究早期生活应激和精神病理学的模型，但尚未从不对称性方面进行研究。本研究旨在调查延长的母婴分离是否会导致大鼠转弯行为出现非典型的左向不对称。母婴分离在出生后第2天至第20天进行，随后在出生后第21天至第40天施加第二个应激源。然后在断奶时（幼崽和母鼠）或青春期的高架十字迷宫试验中检查转弯行为的不对称性。使用深度学习软件包DeepLabCut计算每只动物的左右转弯次数，该软件包可实现无标记姿态估计。然后，为每只动物确定一个偏侧化商（LQ），以研究不对称的强度和偏好侧。LQ分析显示，延长应激组存在显著的左向不对称。此外，分析转弯次数发现，该组总的左转次数明显多于右转次数。对照动物的转弯行为没有不对称性。这些结果表明，出生后早期的延长应激导致了非典型的左向转弯行为。应激诱导的非典型不对称可能是早期生活应激和精神疾病发展的一个介导因素。
