Figure 4. LAT1 in LepR-expressing neurons is involved in energy homeostasis and BAT function.

(A–F) Food intake (A), locomotor activity (B), O₂ consumption (C), CO₂ production (D), energy expenditure (E), and body temperature (F) were measured in singly housed LepR-Cre Slc7a5^fl/fl mice and control mice at 22–24 weeks of age (n = 7 to 10, *P < 0.05, **P < 0.01, ***P < 0.001, 2-tailed Student’s t test). (G–I) Representative picture of BAT (G), tissue weights (H), and tissue weights normalized to body weight (I) are shown for LepR-Cre Slc7a5^fl/fl mice and control mice at 22–24 weeks of age (n = 17 or 18, **P < 0.01, ***P < 0.001, 2-tailed Student’s t test). Scale bar, 1 cm. (J) H&E stain was performed on the BAT of LepR-Cre Slc7a5^fl/fl mice and control mice at 22–24 weeks of age. Scale bar, 100 μm. (K) Transmission electron microscopy analysis was performed on the BAT of LepR-Cre Slc7a5^fl/fl mice and control mice at 22–24 weeks of age. Scale bar, 10 μm. (L and M) mtDNA content of BAT (L) and mRNA expression (M) were measured in LepR-Cre Slc7a5^fl/fl mice and control mice at 22–24 weeks of age (n = 3 to 4, *P < 0.05, **P < 0.01, ***P < 0.001, 2-tailed Student’s t test). All the mice used in this study were male.