Fig. 1

Expression of 5-HT1A in the glutamatergic and GABAergic neurons of the insular cortex. a. Molecular diagram of 5-HT1A coupled to an inhibitory G protein. b. Experimental design to identify 5-HT1A-expressing (5-HT1A+) glutamatergic and GABAergic neurons in the insula using immunofluorescent staining in horizontal brain slice of wild-type mouse. c. 5-HT1A antibody staining of soma 5-HT1A-autoreceptors in neurons of the dorsal raphe nucleus (DRN). d. Definition of the analyzed area in the anterior and posterior insula in horizontal brain slices (3.60 mm ventral to Bregma). e-f. Image of DNA staining and immunofluorescent signal of NeuN and GAD67 in the anterior (e) and posterior (f) insula. White lines indicate the division of cortical layers in the insula. g-h. Representative images of 5-HT1A+ glutamatergic (g) and GABAergic neurons (h) in the insula. Yellow arrows indicate 5-HT1A expression. i. Percentage of 5-HT1A expression in glutamatergic (Glu) and GABAergic (GABA) neurons in the anterior (ICa) and posterior insula (ICp). Total glutamatergic neurons: ICa + ICp = 1966 + 2359 = 4325; Total GABAergic neurons: ICa + ICp = 513 + 373 = 886; n = 4 mice j. The proportion of 5-HT1A+ neurons is significantly higher in the glutamatergic than in the GABAergic population (paired t-test, ***p < 0.001), n = 4 mice, 2 locations per mouse