The use of infrared technology as a novel approach for studies with female laboratory animals

AIM: To determine the changes in skin temperature and brown adipose tissue (BAT) activity throughout the estrous cycle as well as the regularity of the estrous cycle in mice. METHODS: We assessed the differences in the duration of the estrous cycle and its phases between 3- and 8-month-old female mice (n = 18). Skin temperature and BAT activity were measured by infrared technology and compared with human menstrual cycle. RESULTS: Young and old female mice did not differ significantly in the estrous cycle length. However, young animals had longer diestrus and shorter proestrus phase. In contrast with women, mice showed age-dependent changes in body temperature and BAT activity during the estrus cycle. CONCLUSION: Establishing the pattern of temperature and BAT activity changes could be used to determine the estrous cycle phase before performing experiments without disturbing the animal. However, since the regulation of BAT activity during the estrous cycle was age-dependent, very complex, and varied significantly from women, further studies are needed to develop a non-invasive method for determining the phase of the estrous cycle.