CNR1 and glucose measurement: In previous studies, we have investigated glucose tolerance in chow-fed rats using another CB1 antagonist, AM251, and this drug was found to increase glucose tolerance at low doses (0.01-0.2 mg/kg), whereas it had no effect at higher doses (1 mg/kg) (Bermudez-Silva et al., 2007; Bermúdez-Siva et al., 2006).