The rat model of social isolation during development is commonly employed for studying the effects of early life stress on later behavior, such as mental illnesses and brain activity, and has been well reviewed by recent articles (Arakawa, 2018; Burke, McCormick, Pellis, & Lukkes, 2017; Robbins, 2016). The normal function of rodents and other social animals is dependent on a well-organized repertoire of social behaviors. In fact, the most significant effects of rearing rats in isolation are reported to occur during weaning to early adulthood, which is a critical phase (Arakawa, 2005; Ferdman, Murmu, Bock, Braun, & Leshem, 2007). In addition, recent studies have reported that various emotional and behavioral changes occur as a result of social isolation, including an increase in aggressiveness (Krupina,