Zeng Haiyan, Yu Zijia, Huang Qingjun, Xu Haiyun
The Mental Health Center, Shantou University Medical College, Shantou, China.
Xianyue Hospital/Xiamen Mental Health Center, Xiamen, China.
Front Behav Neurosci. 2021 Apr 7;15:637678. doi: 10.3389/fnbeh.2021.637678. eCollection 2021.
Attachment insecurity in the forms of attachment anxiety and avoidance is associated with mental disorders in humans. In this research field, rodents, especially mice and rats, are commonly used to study social behaviors and underlying biological mechanisms due to their pronounced sociability. However, quantitative assessment of attachment security/insecurity in rodents has been a major challenge. The present study identified attachment insecurity behaviors in rats subjected to maternal separation (MS) during postnatal days (PD) 2-16 and early weaning (EW) during PD 17-21. This MSEW procedure has been used to mimic early life neglect in humans. After MSEW, rats continued to survive until early adulthood when they were subjected to open-field, social interaction, and elevated-plus maze tests. Compared to CNT rats in either gender, MSEW rats moved longer distances at higher velocities in the open-field. The MSEW rats also showed lower ratios of travel distance at central zone over that on whole arena of the open-field compared to CNT rats. In social interaction test, male CNT rats preferred to investigate an empty cage than females; whereas female CNT rats spent more time with a partner-containing cage as compared to males. This gender-specific difference was reversed in MSEW rats. On elevated-plus maze female CNT rats exhibited more risk-taking behaviors as compared to male counterparts. Moreover, female MSEW rats experienced a greater difficulty in making a decision on whether approaching to or averting from which arms of elevated-plus maze. Taken together, male MSEW rats behaved like attachment anxiety while females' phenotype is alike to attachment avoidance described in humans. These results shall prompt further application of MSEW rat in abnormal psychology and biological psychiatry research.
以依恋焦虑和回避形式存在的依恋不安全感与人类的精神障碍有关。在这个研究领域，啮齿动物，尤其是小鼠和大鼠，由于其明显的社会性，常被用于研究社会行为及潜在的生物学机制。然而，对啮齿动物依恋安全感/不安全感进行定量评估一直是一项重大挑战。本研究确定了在出生后第2 - 16天经历母婴分离（MS）和在第17 - 21天经历早期断奶（EW）的大鼠中的依恋不安全感行为。这种MS - EW程序已被用于模拟人类早期生活中的忽视情况。经过MS - EW后，大鼠继续存活至成年早期，此时对它们进行旷场试验、社交互动试验和高架十字迷宫试验。与两种性别的对照大鼠相比，经历MS - EW的大鼠在旷场试验中以更高的速度移动更长的距离。与对照大鼠相比，经历MS - EW的大鼠在旷场试验中央区域的移动距离与整个旷场移动距离的比值也更低。在社交互动试验中，雄性对照大鼠比雌性更倾向于探究空笼子；而雌性对照大鼠与装有同伴的笼子相处的时间比雄性更长。这种性别特异性差异在经历MS - EW的大鼠中发生了逆转。在高架十字迷宫试验中，雌性对照大鼠比雄性对照大鼠表现出更多的冒险行为。此外，雌性经历MS - EW的大鼠在决定接近或避开高架十字迷宫的哪些臂时遇到更大困难。综上所述，雄性经历MS - EW的大鼠表现出类似依恋焦虑的行为，而雌性的表型类似于人类中描述的依恋回避。这些结果将促使MS - EW大鼠在异常心理学和生物精神病学研究中得到进一步应用。
