Figure 7. GDF15 is required to regulate core body temperature in cold-exposed OPA1 BKO mice.
(A) Averaged core body temperature (light and dark cycles) collected from 12-week-old wild-type (WT) and OPA1/GDF15 brown adipose tissue (BAT) double-knockout (DKO) mice after 7 d at 30°C. (B) Averaged core body temperature (light and dark cycles) in mice cold exposed for 24 hr (4°C). (C) Final core body temperature recorded by telemetry in mice exposed to 4°C in the CLAMS system. (D–G) Indirect calorimetry data represented as the average for the light and dark cycles during the first 24 hr of data recording (4°C). (D) Energy expenditure. (E) Respiratory exchange ratio. (F) Food intake. (G) Locomotor activity. (H) Hourly core body temperatures collected from 12-week-old WT and DKO mice during cold exposure (4°C). (I–N) Data collected after 5 hr of cold exposure. (I) Relative mRNA expression of thermogenic genes in BAT after 5 hr of cold exposure normalized to tata box protein (Tbp). (J) Representative immunoblots for UCP1 in BAT normalized to β-actin and their respective densitometric quantification. (K) Pyruvate-malate-supported oxygen consumption rates (OCRs) and UCP1-dependent respirations in mitochondria isolated from BAT (baseline conditions). (L) Relative mRNA expression of thermogenic genes in inguinal white adipose tissue (iWAT) normalized to Tbp expression. (M) Representative immunoblots for UCP1 in iWAT normalized to β-actin and their respective densitometric quantification. (N) Representative immunoblots for Serca1a in gastrocnemius muscle normalized to Ponceau red staining and their respective densitometric quantification. Optical density (OD). Data are expressed as means ± SEM. Significant differences were determined by Student’s t-test using a significance level of p<0.05. * p <0.05; ** p <0.01. Significantly different vs. WT mice.