Figure 3.

Involvement of type I cannabinoid (CB₁) receptors in the fear-attenuating effect of the high 3:6 ratio diet. (a) Administration of the CB₁ receptor antagonist rimonabant (RIM, 3 mg/kg) 60 min before the test abolished the effect of the 5% krill diet on fear memory (n=10 per group). (b) Time course of the freezing rate during the test session in (a). (c) Administration of the μ-opioid receptor antagonist naloxone (NLX, 3 mg/kg) 60 min before the test did not change the effect of the 5% krill diet on fear memory (n=10 per group). (d) Time course of the freezing rate during the test session in (c). (e and f) Quantitative polymerase chain reaction (PCR) for CB₁ receptor (e) and diacylglycerol lipase α (DGLα; f) analyses of brain extracts from mice fed the control 1 and 5% krill diets (n=6 per group). VEH, vehicle. All data are shown as means±SEM.*P<0.05, **P<0.01, two-way analysis of variance (ANOVA) and post hoc Bonferroni comparison.