Short-term thermal responses after exposure to predator odor (TMT) in the house mouse

Abstract

Exposure to predator cues is believed to induce fear-like responses in prey species and compounds found in the smells of predators, such as TMT (2,5-dihydro-2,4,5-trimethylthiazole) are frequently used to induce such responses. While behavioral changes of rodents after exposure to TMT have been well characterized, only few studies described the associated sympathetic responses. Here, we used non-invasive infrared thermography to assess short-term and fine-scale changes in peripheral body temperature of wild-origin house mice (Mus musculus domesticus) subjected to TMT. Peripheral temperature changes are associated with blood flow regulation occurring when mammals are subjected to emotion-eliciting situations. Our results revealed that confrontation to TMT induced clear peripheral thermal responses characterized by a significant increase in tail temperature and in the maximum peripheral body temperature. The increase in tail temperature is not the typical physiological stress response expected when mice are exposed to a fear-eliciting situation. In addition, mice did not express typical defensive behaviors such as freezing and avoidance. These results suggest that in our experimental conditions, TMT, as an indirect, chemical predator cue, induced arousal rather than fear. In conclusion, this study stresses the need for a deeper exploration of the behavioral and physiological response to predator odors to better understand the emotional responses they induce.