Fig. 1

AA increased body temperature and energy intake. a Rectal temperature of control group and cold water group from 0 to 14th day. b Rectal temperature of control + cold group and CH group on the14th day. c Representative infrared images of rats in control group, CH group, and CH + AA group before sacrifice. The black arrow points to the temperature measurement location, including the eyes, back, and abdomen. Temperature trends during AA treatment, including d rectal temperature and surface body temperature including eye temperature (e), dorsal temperature (f), and ventral temperature (g).  Rectal temperature (h), eye temperature (i), dorsal temperature (j), and ventral temperature (k) on the 21st day. (l–n) Average food intake (l), calories in consumed food (m), and energy intake (n) per 24 h in the last three days. o Body weight on the 21st day. Control, CH, and CH + AA represent groups intermittently exposed to warm water (32 ± 0.5 °C), cold water (3.5 ± 0.5 °C), and cold water plus AA, respectively. Data were expressed as mean ± standard deviation (SD) (n = 6 rats/group). Differences were evaluated by unpaired two-tailed Student’s t-test or one-way ANOVA with a post hoc Student–Newman–Keuls test (*P < 0.05, **P < 0.01, ***P < 0.001, and ns represents no significant difference)