Spontaneous behavior and sleep-wakefulness cycle in isolated and paired REM sleep deprived-marihuana treated rats.

The correlation between marihuana-induced aggressive behavior and changes in the sleep-wakefulness cycle was studied in chronically implanted rats. Marihuana injection in non-REM deprived rats did not induce aggressiveness irrespective of the animals being caged in isolation or paired. During this procedure quantization of the sleep-awake cycle revealed that wakefulness was increased while slow wave and REM sleep were decreased, mainly in the paired animals. REM deprived-marihuana injected animals recorded in isolation behaved like the control solution-injected rats. They showed a large rebound of REM and were not aggressive at the end of the 8 hr sessions. Conversely, when these animals were paired during the recording periods, they remained continuously awake and showed numerous episodes of aggressiveness. These results suggest that the aggressiveness inducing properties of marihuana are related to the REM deprivation and to the increased environmental stimulation achieved by pairing the animals.