Skip to main content
. Author manuscript; available in PMC: 2020 Nov 6.
Published in final edited form as: Cell Metab. 2014 Feb 4;19(2):302–309. doi: 10.1016/j.cmet.2013.12.017

Figure 2. Relationship between irisin, FGF21, BAT and temperature.

Figure 2

Cold exposure resulted in reduction in skin temperature [open circles, Panel A], accompanied by a rise in energy expenditure (EE) [closed circles], both reaching significance from 16-12°C. Panels B (by immunoblot) and E (by ELISA) showed positive associations between irisin and EMG fold changes during cold exposure. Panel C compared irisin and EE fold changes during cold exposure with maximal exercise test. Changes in FGF21 levels correlated negatively with shivering [Panel D] but positively with thermogenic response (TR; difference between supraclavicular skin and chest T°C) [Panel F]. Panels G-H showed representative PET-CT images of BAT positive (N=3) and negative (N=2) individuals, respectively (BAT in red). FGF21 diurnal reduction was more markedly blunted in BAT positive (solid lines) compared to negative (dashed lines) individuals at 19°C [Panel L] vs. 24°C [Panel K]. Panels I-J compared FGF21 changes (N=5) measured between 8-10 am at either warm (27°C) or shivering (12°C) conditions. FGF21 reduction was significantly blunted in the cold. *P<0.05 compared to warm condition; #p<0.001 compared to cold exposure. Data are presented as mean ± SD.