Fig. 5

Expression of 5-HT2A in glutamatergic, GABAergic and projection-specific populations of the insular cortex. a. Molecular diagram of the serotonin 2A receptor (5-HT2A) coupled to an excitatory G-protein. b. Horizontal brain slice of wild-type mouse used in immunofluorescent staining. c-d. Representative images of 5-HT2A-expressing (5-HT2A+) glutamatergic (c) and GABAergic neurons (d) in the insula. Yellow arrows indicate 5-HT2A expression. e. Percentage of 5-HT2A expression in the glutamatergic (Glu) and GABAergic (GABA) neurons in the anterior (ICa) and posterior (ICp) insula. f. The proportion of 5-HT2A+ neurons is significantly higher in glutamatergic than GABAergic populations (paired t-test, ***p < 0.001). Total glutamatergic neurons: ICa + ICp = 2444 + 2783 = 5227; Total GABAergic neurons: ICa + ICp = 542 + 577 = 1119; n = 4 mice. g-h. Representative fluorescent images of CTB-labelled neurons (IC-BLA and IC-CeA projection neurons) expressing 5-HT2A in the insula. Yellow arrows indicate 5-HT2A expression. i. Percentage of 5-HT2A expression in neurons projecting to the central and basolateral amygdala (CeA and BLA) in the anterior and posterior insula. j. The proportions of 5-HT2A+ neurons are not different between IC-BLA and IC-CeA populations (unpaired t-test, p > 0.05). Total IC-BLA neurons: ICa + ICp = 424 + 324 = 748; Total IC-CeA neurons: ICa + ICp = 526 + 523 = 1049; n = 7 mice, 2 locations per mouse. k. The percentage of 5-HT2A expression in neurons projecting to rostral and caudal parts of the lateral hypothalamus (rLH and cLH) in the anterior and posterior insula. l. The proportions of 5-HT2A+ neurons are not different between IC-rLH and IC-cLH populations (unpaired t-test, p > 0.05). Total IC-rLH neurons: ICa + ICp = 530 + 330 = 860; Total IC-CeA neurons: ICa + ICp = 563 + 259 = 822; n = 5 mice, 2 locations per mouse