Figure 1. Aged mice exhibit decreased iWAT beiging in response to cold exposure or β3-agonist treatment.

(A) Young (9-week-old) and aged (57-week-old) C57BL/6 mice were acclimated to 30 °C for 3 weeks, followed by two additional weeks either remaining at 30 °C (TN, thermoneutral), spending the last 3 days at 6 °C (3D, acute cold) or the last 14 days at 6 °C (14D, chronic cold). (B) Relative mRNA levels of thermogenic marker genes in mouse iWAT from (A), n=5. (C) Immunofluorescence analysis of UCP1 (green) and DAPI (blue) in iWAT sections from mice in (A), LN = lymph node. Scale bar 100 μm. (D–F) Relative mRNA levels of Ucp1 and Cidea in iWAT from separate groups of young and aged mice that were either: exposed to 6 °C cold for 6 weeks (D), treated with CL-316,243 for 1 hr (E) or treated with CL 316,243 for 5 days (F). Data represent mean ± SEM, points represent biological replicates, two groups analyzed using a Student’s t-test, and multiple conditions analyzed using a two-way ANOVA with a Tukey correction for multiple comparisons. Significance: not significant, p>0.05; * p<0.05 ** p<0.01; *** p<0.001.

Figure 1—figure supplement 1. Aging impairs WAT beiging.

(A, B) Body mass and iWAT mass of mice described in Figure 1A, n=5. (C) Mouse dissection with lymph node (LN) orientation showing the dorsolumbar and inguinal regions of the iWAT pad. (D) IF analysis of UCP1 (green) in iWAT, DAPI (nuclei, blue). LN = lymph node. Scale bar 100 μm. (E) mRNA levels of Ucp1 and Cidea in BAT of young and aged mice housed at TN, and either maintained at TN or exposed to cold for 2 weeks. (F) H&E staining of serial sections of iWAT from D (above) and Figure 1C, LN = lymph node. Scale bar 100 μm. Data represent mean ± SEM, points represent biological replicates, analyzed using a Student’s t-test with a two-way ANOVA with a Tukey correction for multiple comparisons. Significance: not significant, p>0.05; * p<0.05 ** p<0.01; *** p<0.001.