Figure 2. Hypothalamic control of hunger- and satiety-associated interoceptive cues.

(A) Surgery schematic for experimental and control viral cocktail injections into the ARC of Agrp^Cre mice or the LH of Vgat^Cre and Vglut2^Cre mice.

(B) Representative images showing optical fiber placement in the ARC of Agrp^Cre mice or in the LH of Vgat^Cre and Vglut2^Cre mice. Scale bar = 500 μm.

(C) 20× confocal images demonstrating colocalization of ChR2-YFP (green) and hM4D-mCherry (red) in the ARC of Agrp^Cre mice and in the LH of Vgat^Cre and Vglut2^Cre mice. Scale bar = 50 μm.

(D) ARC^AGRP activation in sated mice triggers hunger. Upper panel, one-way repeated-measures ANOVA revealed a significant effect of photostimulation in ARC^AGRP:ChR2 mice (n = 6; F(1.62, 8.11) = 14.12, p = 0.003; Dunnett’s post-test: no stim vs. 10 Hz,*p = 0.022; no stim vs. 20 Hz, ***p = 0.001) on fasted-associated lever responding. No significant effects were observed in YFP controls (n = 6; paired t test: t(5) = 0.53, p = 0.62). Lower panel, no effects of photostimulation on response rate were observed in ARC^AGRP:ChR2 (F(1.98, 9.92) = 0.29, p = 0.75) or ARC^AGRP:YFP mice (t(5) = 0.37, p = 0.73).

(E) ARC^AGRP inhibition in fasted mice does not decrease hunger. Upper panel, two-way mixed-model ANOVA found no significant effects of ARC^AGRP inhibition on fasted-associated lever responding (n = 6 mice per group; group × treatment interaction: F(1, 10) = 1.81, p = 0.21) or response rate (lower panel, F(1, 10) = 0.70, p = 0.42).

(F) LH^VGAT activation in sated mice does not evoke hunger. Upper panel, no significant effects of photostimulation in LH^VGAT:ChR2 mice (n = 6; F(1.71, 8.56) = 4.32, p = 0.055) or LH^VGAT:YFP mice (n = 6; t(5) = 1.61, p = 0.17) were observed. Lower panel, no effects of photostimulation on response rate were observed in LH^VGAT:ChR2 (F(2.39, 11.95) = 2.59, p = 0.11) or LH^VGAT:YFP mice (t(5) = 0.82, p = 0.45).

(G) LH^VGAT inhibition in fasted mice decreases hunger. Upper panel, two-way mixed-model ANOVA found a significant effect of LH^VGAT inhibition on fasted-associated lever responding (n = 6 mice per group; group × treatment interaction: F(1, 10) = 10.47, p = 0.0089; Bonferroni’s post-test **p = 0.0013). Lower panel, no effects of inhibition were observed on response rate (F(1, 10) = 0.18, p = 0.68).

(H) LH^VGLUT2 activation in fasted mice decreases hunger. Upper panel, one-way repeated-measures ANOVA revealed a significant effect of photostimulation in LH^VGLUT2:ChR2 mice (n = 5; F(2.08, 8.31) = 7.06, p = 0.016; Dunnett’s post-test: no stim vs. 2 Hz,*p = 0.042; no stim vs. 5 Hz,*p = 0.016; no stim vs. 10 Hz,*p = 0.016; no stim vs. 20 Hz, *p = 0.015) on fasted-associated lever responding. No significant effects were observed in YFP controls (n = 6; paired t test: t(5) = 0.58, p = 0.59). Lower panel, photostimulation significantly decreased response rate in LH^VGLUT2:ChR2 (F(2.07, 8.28) = 10.60, p = 0.005; Dunnett’s post-test: no stim vs. 20 Hz, *p = 0.013) but not LH^VGLUT2:YFP mice (t(5) = 0.92, p = 0.40).

(I) LH^VGLUT2 inhibition in sated mice does not induce hunger. Upper panel, two-way mixed-model ANOVA found no significant effects of LH^VGLUT2 inhibition on fasted-associated lever responding (n = 5 LH^VGLUT2:ChR2 and n = 6 LH^VGLUT2:YFP; group × treatment interaction: F(1, 9) = 0.0035, p = 0.95) or response rate (lower panel, F(1, 9) = 1.20, p = 0.30).

See also Figure S1.