The effect of ACTH (0.2 mg·kg−1) on blood THC and THC-COOH concentrations in rats (200–250 g) that were repeatedly pretreated with THC (10 mg·kg−1·day−1) for 10 days before a 2 day washout period (n= 8 per group). *P < 0.05 and ***P < 0.001, significant difference between ACTH and VEH. ACTH, adrenocorticotrophic hormone; THC, Δ9-tetrahydrocannabinol; THC-COOH, (-)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol; VEH, vehicle.