Fig. 7: Acute activation of OB→MS projections before food ingestion reduces food intake.
From: A food-sensitive olfactory circuit drives anticipatory satiety
a, Schematic of 2P calcium imaging in the dorsal OB of awake head-fixed Tbx21GCaMP6f animals and representative image of GCaMP6f fluorescence. Scale bar, 50 µm. b, Sniffing behaviour of fasted C57BL/6N mice exposed to food odours and average sniffing frequency (n = 4 mice). c, Distribution of sniffing exploration events (0.5–4.5 s) monitored in the home cage (grey, n = 4 mice) and odour pulse duration in imaging experiments (green). d, Example calcium activity traces of a representative neuron (region of interest indicated by the yellow circle in a) in response to food odours (green) of varying duration depicted as the mean ± s.e.m. (n = 10–130 trials). e, Schematic of optogenetic stimulation of OB→MS projections in Tbx21ChR2-tdTomato mice. f, Representative images of MTC projections in the MS of Tbx21ChR2-tdTomato mice (tdTomato, red; DAPI, blue). Scale bars, 100 µm. g, Representative images of photostimulation-induced FOS immunoreactivity in Tbx21ChR2-tdTomato and Tbx21-Cre-negative control mice (FOS, green; DAPI, blue). Scale bars, 100 µm. h–l, Cumulative food intake and AUC of optogenetically stimulated Tbx21ChR2-tdTomato mice (stimulation, blue line) and control mice (no stimulation, grey/black line), following 10 min pre-stimulation before the dark cycle (time curve: paired two-way ANOVA, Sidak post hoc; n = 8 mice; AUC: paired two-tailed Student’s t-test; n = 8 mice; P = 0.0078; h), following a 10-min stimulation during the dark cycle (time curve: paired two-way ANOVA; Sidak post hoc; n = 8 mice; AUC: paired two-tailed Student’s t-test; n = 8 mice; i), during a 180-min stimulation during the dark cycle (time curve: two-way ANOVA, Sidak post hoc; n = 10 mice; AUC: paired two-tailed Student’s t-test; n = 10 mice; j), during a 180-min stimulation after a 16-h overnight fast during the light cycle (time curve: paired two-way ANOVA, Sidak post hoc; n = 9 mice; AUC: paired two-tailed Student’s t-test; n = 9 mice; k) and following 180 min pre-stimulation before the dark cycle (time curve: paired two-way ANOVA, Sidak post hoc; n = 7 mice; AUC: paired two-tailed Student’s t-test; n = 7 mice; l). m, Behavioural test 60 min following a 10-min stimulation of Tbx21ChR2-tdTomato (ChR2) and Tbx21-Cre-negative (control) animals. n, Open field test depicted as average time spent per area (border versus centre; two-way ANOVA, Tukey post hoc; n = 6 control mice, n = 9 ChR2 mice). o, Food finding test (unpaired two-tailed Student’s t-test; n = 6 control mice, n = 9 ChR2 mice). Data are represented as the mean ± s.e.m. *P ≤ 0.05, **P ≤ 0.01. Mouse images in a, e and h–l adapted from SciDraw under a Creative Commons license CC BY 4.0.
