Fig 1.
Leptin deficient animals fail to defend normothermia at temperatures lower than thermoneutrality.
(A) Study design, (B) change in body weight, (C) core body temperature across all photoperiods, (D) photoperiod-averaged core body temperature profiles, and (E) the relationship between core temperature and ambient temperature in adult male ob/ob mice and wild-type (WT) littermate controls implanted with temperature transponders for continuous measures of core body temperature and housed under different ambient temperature conditions (n = 7/group). Arrowheads mark measures of body weight. Mean±SEM. ****p<0.0001, ***p<0.001, *p<0.05.
Fig 2.
Leptin deficient animals are unable to maintain energy homeostasis in response to a thermal challenge.
(A) Study design, (B) body weight, (C) fat mass, (D) change in body weight, (E) change in fat mass and (F) change in lean body mass in adult male ob/ob mice and wild-type (WT) littermate controls housed under different ambient temperature conditions (n = 8/group). Arrowheads mark measures of body weight and composition. Mean±SEM. ****p<0.0001, ***p<0.001, *p<0.05.
Fig 3.
Leptin signaling is required for adaptive changes in energy intake in response to a thermal challenge.
(A) Photoperiod-averaged energy intake profiles and (B) the relationship between energy intake and ambient temperature in adult male ob/ob mice and wild-type (WT) littermate controls housed under different ambient temperature conditions (n = 8/group). Mean±SEM. ***p<0.001, *p<0.05.
Fig 4.
Leptin deficiency does not impair the whole body heat production response to cold stress in mice.
(A) Energy expenditure across all photoperiods, (B) photoperiod-averaged energy expenditure (EE) profiles and (C) the relationship between energy expenditure and ambient temperature in adult male ob/ob mice and wild-type (WT) littermate controls housed under different ambient temperature conditions (n = 8/group). (D) Regression of natural log (ln) of mean 24h EE values on the natural log of the mean difference between core temperature (Tc) and ambient temperature (Ta) (see S1 Fig.). Mean±SEM. ****p<0.0001, ***p<0.001, **p<0.01.
Fig 5.
Adaptive changes of energy intake, but not energy expenditure in response to different ambient temperatures, requires leptin signaling.
(A) Energy expenditure (EE) and energy intake (EI) expressed as percentages of the values observed at thermoneutrality vs. ambient temperature and (B) whole body thermal conductance calculated from mean 24h energy expenditure vs. ambient temperature in wild-type (WT) and leptin-deficient ob/ob mice using the traditional method [13] (n = 8/group). (C) Comparison of traditional vs. regression methods for estimating whole body thermal conductance as functions of the core minus ambient (Tc—Ta) temperature difference based on 24h data (see S1 Fig.). Mean±SEM. ***p<0.001.
Fig 6.
Ambulatory activity levels do not change at different ambient temperatures.
(A) Ambulatory activity across all photoperiods, (B) photoperiod-averaged ambulatory activity and (C) the relationship between ambulatory activity and ambient temperature in adult male ob/ob mice and wild-type (WT) littermate controls housed under different ambient temperature conditions (n = 8/group). Mean±SEM. ****p<0.0001, ***p<0.001.