Fig. 1: MRN serotonergic neurons are inhibited by rewarding stimuli, and their inhibition elicits conditioned place preference (CPP) and self-stimulation. | Nature Communications

Fig. 1: MRN serotonergic neurons are inhibited by rewarding stimuli, and their inhibition elicits conditioned place preference (CPP) and self-stimulation.

From: Median raphe serotonergic neurons projecting to the interpeduncular nucleus control preference and aversion

Fig. 1: MRN serotonergic neurons are inhibited by rewarding stimuli, and their inhibition elicits conditioned place preference (CPP) and self-stimulation.The alternative text for this image may have been generated using AI.

a, e, k Schematic representation of experiments. b AAV-mTph2-Venus injection into the MRN. Scale bar = 200 μm. c, d Colocalization rate of the transgene (Venus; green) and Tph2 (red) immunoreactivity in the MRN. Scale bars = 20 μm. n = 5 mice. f Fiber photometry setup. g Representative raw trace of GCaMP fluorescence. h Top: heatmap of signals (red–blue, high–low). One licking bout per row. Bottom: averaged GCaMP signals of one mouse. n = 10 bouts. i Mean GCaMP signals for seven mice. Lines and shaded areas indicate mean and s.e.m., respectively. Red and blue segments indicate a statistically significant increase and decrease from the baseline (P < 0.05; permutation test). j GCaMP fluorescence response to 10% and 0.5% sucrose solutions. Two-tailed paired t-test t4 = 5.365, **P = 0.0058, n = 5 mice. l CPP test. m CPP scores calculated as spent time in a light stimulation-associated compartment in the posttest subtracted by that in the pretest in the Venus and eArchT mice (two-tailed unpaired t-test, t19 = 2.804, **P = 0.0113, n = 8 (Venus) and 13 (eArchT) mice). n Spent time in the compartment associated with light stimulation was significantly increased after conditioning sessions in the eArchT mice but not in the Venus control mice (eArchT: two-tailed paired t-test (eArchT Pre vs eArchT Post), t12 = 4.810, ***P = 0.0004, n = 13 mice; Venus: two-tailed paired t-test (Venus Pre vs Venus Post), t7 = 0.3553, P = 0.7328, n = 8 mice). o Schematic of the nose poke self-stimulation test. Greenlight (3 s duration, 1 pulse/poke, 5 mW) was delivered when mice performed nose poke responses. p The number of nose poke in the Venus and eArchT mice (two-way repeated-measures ANOVA, virus (Venus or eArchT) × time (day 1, 2, 3, or 4) interaction F3,60 = 1.925, P = 0.1351, the effect of virus F1,20 = 38.40, ***P < 0.001, the effect of time F3,60 = 0.7157, P = 0.5464, n = 12 (Venus) and 10 (eArchT) mice). Data are presented as mean ± s.e.m. Error bars indicate s.e.m. Source data are provided as a Source Data file.

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