title: Estimation of the core temperature control during ambient temperature changes and the influence of circadian rhythm and metabolic conditions in mice.
abstract: It has been speculated that the control of core temperature is modulated by physiological demands. We could not prove the modulation because we did not have a good method to evaluate the control. In the present study, the control of core temperature in mice was assessed by exposing them to various ambient temperatures (Ta), and the influence of circadian rhythm and feeding condition was evaluated. Male ICR mice (n=20) were placed in a box where Ta was increased or decreased from 27°C to 40°C or to -4°C (0.15°C/min) at 0800 and 2000 (daytime and nighttime, respectively). Intra-abdominal temperature (Tcore) was monitored by telemetry. The relationship between Tcore and Ta was assessed. The range of Ta where Tcore was relatively stable (range of normothermia, RNT) and Tcore corresponding to the RNT median (regulated Tcore) were estimated by model analysis. In fed mice, the regression slope within the RNT was smaller in the nighttime than in the daytime (0.02 and 0.06, respectively), and the regulated Tcore was higher in the nighttime than in the daytime (37.5°C and 36.0°C, respectively). In the fasted mice, the slope remained unchanged, and the regulated Tcore decreased in the nighttime (0.05 and 35.9°C, respectively), while the slopes in the daytime became greater (0.13). Without the estimating individual thermoregulatory response such as metabolic heat production and skin vasodilation, the analysis of the Ta-Tcore relationship could describe the character of the core temperature control. The present results show that the character of the system changes depending on time of day and feeding conditions.
authors.affiliation: Sport Science Center for Active Life, Faculty of Sport Sciences, Waseda University, Tokorozawa, Japan; Body Temperature and Fluid Laboratory (Laboratory of Integrative Physiology), Faculty of Human Sciences, Waseda University, Mikajima 2-579-15, Tokorozawa, Saitama 359-1192 Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Tokizawa
authors.affiliation: Faculty of International Liberal Arts, Dokkyo University, Soka, Japan.
authors.forename: Tamae
authors.initials: T
authors.lastname: Yoda
authors.affiliation: Body Temperature and Fluid Laboratory (Laboratory of Integrative Physiology), Faculty of Human Sciences, Waseda University, Mikajima 2-579-15, Tokorozawa, Saitama 359-1192 Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Uchida
authors.affiliation: Sport Science Center for Active Life, Faculty of Sport Sciences, Waseda University, Tokorozawa, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kanosue
authors.affiliation: Body Temperature and Fluid Laboratory (Laboratory of Integrative Physiology), Faculty of Human Sciences, Waseda University, Mikajima 2-579-15, Tokorozawa, Saitama 359-1192 Japan; Institute of Applied Brain Sciences, Waseda University, Tokorozawa, Japan. Electronic address: k-nagashima@waseda.jp.
authors.forename: Kei
authors.initials: K
authors.lastname: Nagashima
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation; D002940:Circadian Rhythm; D005215:Fasting / Q000378:metabolism; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009043:Motor Activity; D010101:Oxygen Consumption; D013696:Temperature
keywords: Behavioral thermoregulation; Fasting; Heat balance; Metabolism; Physical activity; Thermoregulation