Physical contact with cage mates modifies stress-induced hyperthermia in mice

Abstract

Using stress-induced hyperthermia (SIH) as an assay of stress levels, the effects of physical contact with conspecifics on restraint stress and the recovery from it were examined in mice. Restrained mice surrounded by freely moving cage mates showed enhanced SIH due to social inequality aversion. However, this stress enhancement was not observed when the subject was physically separated from cage mates by a transparent acrylic tube. Interestingly, social inequality in the dark room experimental paradigm enhanced SIH, which suggests that visual information does not play a crucial role in stress enhancement. Following release from restraint stress, the body temperatures of the mice gradually returned to baseline levels; this decrease was more rapid when the mice were placed in their home cage with cage mates. However, blocking physical contact using a transparent acrylic tube abolished the social facilitation of body temperature recovery. These results suggest that physical contact plays a crucial role in both stress emergence and recovery via social modification.