(A) Schematic coronal section of a mouse brain showing the lateral hypothalamus (LH, red box), the region where orexin neurons reside and where orexin cells were counted. The green box represents the area depicted in photomicrographs in (D) to (F). (B) Photomicrograph of the lateral hypothalamus showing presynaptic glutamate vesicles (VGLUT1 immuno-labeling, green) in close proximity to orexin cell bodies (orexin-A immuno-labeling, red) at ×40 magnification. (C) Quantification of orexin neurons expressing c-Fos, a marker of neural activation, after the 3-hour wake challenge. There was decreased orexin activation after TBI compared to sham mice, which was restored with BCAA therapy (F = 22.47, P < 0.0001; TBI versus sham P < 0.001, TBI versus TBI + BCAA P < 0.01; one-way ANOVA followed by Dunnett’s post hoc test; n = 5 per group). (D to F) Representative photomicrographs of the lateral hypothalamus from sham, TBI, and TBI + BCAA mice showing orexin (red) colocalization with c-Fos (green) at ×20 magnification. F, fornix. Scale bars, 50 μm. **P < 0.01, ***P < 0.001.