Effects of chemogenetic inhibition on the number of c-Fos-positive cells in the CeM after exposure to natural (green) and pharmacological (blue) rewards. Mice exposed to sugar were sacrificed 2 h after the placement in the cage with access to sweet water (or freshwater in control mice) on the seventh day of the protocol. Mice exposed to cocaine were sacrificed 2 h after the i.p. injection of 20 mg/kg of cocaine solution (or saline in control mice) on the seventh day of the protocol. Each dot on the bar graph represents an averaged value of c-Fos-positive cells from one animal. Circles represent results for individual mice for males (filled circles) and females (empty dots). Number of mice for mCherry: N water = 9, sugar = 8, N saline = 6, N cocaine = 6. For hM3Dq: N water = 5, sugar = 7, saline = 6, cocaine = 7. For hM4Di: N water = 6, sugar = 7, saline = 9, cocaine = 7. For c-Fos expression: hM3Dq, N water = 5 (10), sugar = 7 (16), saline = 6 (10), cocaine = 7 (13). For hM4Di: N water = 6 (11), sugar = 7 (14), saline = 9 (18), cocaine = 7 (16), where N = number of mice (total number of slices).*p < 0.05,***p < 0.0001. Statistical significance for (B)–(G) was evaluated by ANOVA repeated measurements for saline vs. cocaine and water vs. sugar with p = 0.0352 for (B), p = 0.0002 for (C), p = 0.0002 for (F), and p = 0.0006 for (G). For (H) and (I) the statistical significance was evaluated by the Mann-Whitney test (sugar) and the unpaired t test (cocaine) with p values: water vs. sugar = 0.0480 and saline vs. cocaine = 0.0076.
