FIG. 4.

Hypothalamic S6K1 regulates leucine deprivation–stimulated energy expenditure via CRH. Mice received intracerebroventricular injection of adenovirus expressing constitutively active S6K1 (+CAS6K1) or GFP (−CAS6K1), followed by injection of 1 μL artificial cerebral spinal fluid (−CRH) or 1 μL of 1 μg/1 μL CRH (+CRH) once daily via an implanted cannula, synchronized with maintenance on a leucine-deficient (−leu) diet for 7 days. Data are means ± SEM of at least two independent experiments (n = 6 for each group). Statistical significance was determined by the Student t test. *P < 0.01, for the effect of with vs. without CAS6K1 in the absence of CRH; #P < 0.01, for the effect of with vs. without CRH in mice receiving CAS6K1. A: Adrb3 mRNA in BAT. B: Body weight change. C: Adipose tissue mass in proportion to body weight. D: Average food intake. E: Oxygen consumption (VO₂; 24 h). F: RER. G: Physical activity. H: Rectal temperature. I: Ucp1 mRNA in BAT. J: UCP1 protein in BAT (top, Western blot; bottom, quantitative measurements of UCP1 protein relative to actin).