Figure 2. Vagal-independent detection of glucose, but not fat, by hypothalamic neurons.

(A) A complete subdiaphragmatic vagotomy (VGX) was performed to determine how vagal gut-brain signaling contributes to AgRP neuron activity in mice. (B) Average ΔF/F of GCaMP6s signals in AgRP neurons of food-restricted VGX and sham mice following intra-peritoneal (IP) injection of cholecystokinin (CCK, 30 μg/kg). Signals are aligned to the time of injection. Green, 470-nm calcium signal; grey, 405-nm control signal. Dark lines represent means and lighter shaded areas represent SEM. (C) Mean ΔF/F of the 470-nm signal (3-min bins) of VGX and sham mice following IP injection of CCK (n=5/group, two-way repeated measures ANOVA, p<0.001). (D) Average ΔF/F of GCaMP6s signals in AgRP neurons of food-restricted VGX and sham mice with intra-gastric (IG) infusions of fat (1 kcal) (E) Ensure (1 kcal) and (F) glucose (2/3 kcal). Signals are aligned to the start of infusion. (G-I) Mean ΔF/F of the 470-nm signal (3-min bins) of VGX and sham mice following IG infusions of (G) fat (n=4/group, two-way repeated measures ANOVA, p<0.01), (H) Ensure (n=4-6/group, two-way repeated measures ANOVA, ns), and (I) glucose (n=6-7/group, two-way repeated measures ANOVA, ns). Data are expressed as mean ± SEM, ns p>0.05, t-tests and post-hoc comparisons: *p<0.05; ANOVA interaction: ∞∞p<0.01, ∞∞∞p<0.001; ANOVA main effect of group: ☼p<0.05.