Housing temperature affects the acute and chronic metabolic adaptations to exercise in mice

Abstract

Mice are commonly housed at room temperatures below their thermoneutral zone meaning they are exposed to chronic thermal stress. r Endurance exercise induces browning and mitochondrial biogenesis in white adipose tissue of rodents, but there are conflicting reports of this phenomenon in humans. r We hypothesized that the ambient room temperature at which mice are housed could partially explain these discrepant reports between humans and rodents. r We housed mice at room temperature or thermoneutrality and studied their physiological responses to acute and chronic exercise. We found that thermoneutral housing altered running behaviour and glucose homeostasis, and further, that exercise-induced markers of mitochondrial biogenesis and the browning of white adipose tissue were reduced in mice housed at thermoneutrality.

Epinephrine responsiveness is reduced in livers from trained mice

“…Results of the GTT (Figure 1d) indicated a nonsignificant trend (p = .052) in glucose tolerance between groups. Exercise is well known to increase skeletal muscle oxidative capacity McKie et al, 2019;Stanford, Middelbeek, & Goodyear, 2015) and in the current study, we observed consistent exercise-induced increases in the protein content of HKII (p < .001), CYTO C, COX IV, and PGC1α (p < .05; Figure 1e) in the triceps muscle.…”

Effects of electrical stimulation‐induced resistance exercise training on white and brown adipose tissues and plasma meteorin‐like concentration in rats

“…This study has a potential limitation: Recent work (McKie et al, 2019;Raun et al, 2020) has demonstrated that housing mice at subthermal neutral conditions, that is, room temperature, rather than at thermal neutrality can stimulate increases in mitochondrial and thermogenic proteins in adipose tissues with endurance exercise training. Housing temperature (22-24°C) may have impacted our data because the thermoneutral zone of Wistar rats is in the range of 29.5-30.5°C (Romanovsky, Ivanov, & Shimansky, 2002).…”

Exercise training of mice – a heated topic

“…Although not statistically significant, the total running distance completed at 29°C was still ∼20% higher ( P = 0.0614) after the intervention (McKie et al . ). However, the time spend on the wheel was the same at both temperatures, so the mice housed in thermoneutral conditions must have been running at a higher intensity.…”

“…In a recently published paper in The Journal of Physiology , McKie et al . () undertook a detailed description of the importance of housing temperature in exercise training‐induced adaptations of adipose tissue in mice.…”

“…In their recent investigation, McKie et al . () hypothesized that thermoneutral housing of mice would decrease mitochondrial biogenesis and browning of white adipose tissue (WAT) in response to exercise training.…”