Fig. 2

Rimonabant treatment rescues the defective brain bioenergetics and increased peripheral oxidative stress in RTT mice. Mecp2-308 heterozygous female (RTT) mice and wild-type (Wt) controls received intraperitoneal daily injections with the CB1 cannabinoid receptor inverse agonist rimonabant (Rim, 0.3 mg/kg) or vehicle (Veh) for 4 or 7 days; 4 h after the last injection mice were sacrificed and the brains were collected and cryopreserved for analyses of mitochondrial bioenergetics. (A-B) Mitochondria were isolated from cryopreserved tissues and the rate of ATP production by oxidative phosphorylation was determined when succinate was provided as an energy source. RTT brain mitochondria generated lower levels of ATP, and treatment with Rim restored Wt-like ATP production rate. (C-D) The activity of the mitochondrial respiratory chain (MRC) complexes I and V was measured spectrophotometrically in mitochondrial membrane-enriched fractions of cryopreserved brain tissues and is expressed as a percentage of the activity measured in Wt and Veh. Treatment with Rim normalized the reduced complex V activity in the brain of RTT mice, restoring Wt-like levels. The activity of complex I did not differ between the two genotypes and rimonabant did not affect it. (E) The levels of ATP were measured in brain extracts. RTT mice treated with Veh displayed reduced ATP levels in brain homogenates, which were normalized by treatment with Rim. (F) At sacrifice, whole blood was collected to assess treatment effects on peripheral oxidative stress status. RTT mice displayed elevated blood levels of reactive oxidizing species (ROS), indicative of excessive oxidative stress; a 4-day treatment with Rim decreased blood ROS levels in RTT mice. N = 3–6. Data are mean ± SEM. * p < 0.05, *** p < 0.001, two-way ANOVA followed by Tukey’s post-hoc test