Thermographic imaging of mouse across circadian time reveals body surface temperature elevation associated with non-locomotor body movements

PLoS One. 2021 May 28;16(5):e0252447. doi: 10.1371/journal.pone.0252447. eCollection 2021.

Abstract

Circadian clocks orchestrate multiple different physiological rhythms in a well-synchronized manner. However, how these separate rhythms are interconnected is not exactly understood. Here, we developed a method that allows for the real-time simultaneous measurement of locomotor activity and body temperature of mice using infrared video camera imaging. As expected from the literature, temporal profiles of body temperature and locomotor activity were positively correlated with each other. Basically, body temperatures were high when animals were in locomotion. However, interestingly, increases in body temperature were not always associated with the appearance of locomotor activity. Video imaging revealed that mice exhibit non-locomotor activities such as grooming and postural adjustments, which alone induce considerable elevation of body temperature. Noticeably, non-locomotor movements always preceded the initiation of locomotor activity. Nevertheless, non-locomotor movements were not always accompanied by locomotor movements, suggesting that non-locomotor movements provide a mechanism of thermoregulation independent of locomotor activity. In addition, in the current study, we also report the development of a machine learning-based recording method for the detection of circadian feeding and drinking behaviors of mice. Our data illustrate the potential utility of thermal video imaging in the investigation of different physiological rhythms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Temperature Regulation
  • Body Temperature*
  • Circadian Rhythm / physiology*
  • Locomotion
  • Machine Learning
  • Mice
  • Mice, Inbred C57BL
  • Thermography / methods*
  • Video Recording

Grants and funding

This work was supported in part by research grants from the Project for Elucidating and Controlling Mechanisms of Ageing and Longevity of the Japan Agency for Medical Research and Development (JP21gm5010002), the Ministry of Education, Culture, Sports, Science and Technology of Japan (17H01524, 18H04015, 20B307), the Kobayashi Foundation, and the Kusunoki 125 of Kyoto University 125th Anniversary Fund.