Tolerance and dependence to Δ9-tetrahydrocannabinol in rhesus monkeys: Activity assessments

Abstract Cannabis withdrawal upon discontinuation of long-term, heavy Cannabis use is reported in humans; however, methods to establish the nature and intensity of cannabinoid withdrawal, especially directly observable signs, have not been widely established. This study quantified activity in the home cage of rhesus monkeys and examined the extent to which activity can be used to quantify tolerance to and dependence on Δ9-tetrahydrocannabinol (Δ9-THC). Home-cage activity was measured in one group that received Δ9-THC (1 mg/kg s.c.) every 12 h