Measurements of weight and activity in male mice following inhalation of cannabis smoke in a controlled smoke exposure chamber

A smoke exposure device delivering marijuana smoke to mice is described. Standardized smoking conditions were achieved with this unit yielding a concentration of 0.123 mg/liter of delta-9-tetrahydrocannabinol in air. A significant (p < 0.05) decrease in locomotor activity in treated animals was seen following the fourth treatment in a 21-day study where animals were exposed three times weekly for 3 weeks. A significant decrease in body weight for marijuana-exposed animals was also noted. In another study, animals were exposed daily for 7 days. Locomotor activity was significantly decreased in marijuana-exposed animals on Days 6 and 7. There was no significant change in body weight. Following removal from the exposure chamber, the marijuana-exposed animals showed transient hyperactivity (1–3 min) followed by a period of depressed activity lasting 1 hr. Some tolerance to the placebo smoke was seen after the fourth treatment in both studies. Cumulative effects were seen following repeated exposures. These preliminary data suggest that inhalation of marijuana smoke will initiate behavioral changes in mice.