Figure 3: Mean SUVs of the whole brain (globe) and corresponding brain regions.

(a) The mean SUVs of the globe. The mean SUVs of the globe in the acute treatment group were significantly greater (2.82 ± 0.34, n = 6 rats; p < 0.01) than those in the chronic treatment (1.75 ± 0.15, n = 6 rats), wash-out (1.44 ± 0.29 n = 6 rats), and saline (1.57 ± 0.17, n = 6 rats) groups. The chronic treatment group also showed higher mean SUVs, but the differences did not reach statistical significance (p > 0.05). (b) The mean SUVs of corresponding brain regions. The mean SUVs of the inferior colliculus (IC = 3.45 ± 0.50), auditory cortex (AC, 2.92 ± 0.33), hippocampus (HP, 3.07 ± 0.39), amygdala (AMY, 2.64 ± 0.32) and cerebellum (CRB, 2.67 ± 0.51) were significantly greater in the acute treatment group than in the chronic treatment, wash-out, and saline groups (**p < 0.01). The mean SUVs of the IC (2.47 ± 0.27), AC (1.80 ± 0.18), HP (1.94 ± 0.15) and AMY (1.62 ± 0.12), but not CRB (1.64 ± 0.18, p > 0.05) were greater in the chronic treatment group (*p < 0.05) than in the saline group. There were no significant differences in the SUVs between the saline and wash-out groups (p > 0.05). (c) The SUV ratio of corresponding brain regions. The SUV ratio of the AC (1.04 ± 0.02) and HP (1.09 ± 0.06) in the acute treatment group were significantly greater (**p < 0.01) than the saline group, suggesting relatively increased metabolism in the two brain regions of the rats in this group. The IC (1.22 ± 0.08), AMY (0.94 ± 0.04), and CRB (0.94 ± 0.09) did not show significant differences (p > 0.05). The SUV ratio of the IC (1.41 ± 0.14), AC (1.01 ± 0.05), and HP (1.11 ± 0.08), but not the AMY (0.93 ± 0.06; p > 0.05) or CRB (0.94 ± 0.08; p > 0.05), were greater in the chronic treatment group than in the wash-out and saline groups (**p < 0.01). There was also no significant difference in the SUV ratio between the saline and wash-out groups (p > 0.05).