Attack behaviour in mice inhibited by -9-tetrahydrocannabinol

Illicit drug use and violence

This chapter reviews evidence on the relationship between illicit drug use and violence, specifically cannabis, stimulant drugs, and opioids. It summarizes findings of systematic reviews of evidence on cannabis, stimulant drugs, and opioids. It also examines evidence from epidemiological studies of drug use among violent offenders and of violence among persons who use drugs, intervention studies, animal studies, human laboratory studies, and human neuroimaging studies. More studies have examined cannabis because of its higher prevalence of use. There is an association between cannabis use and violence, suggestive evidence of a dose-response relationship between the frequency of cannabis use and violence, and a stronger association in persons with psychoses. There is similar emerging evidence on stimulant use and violence, but evidence on opioids is very limited. There is limited and mixed evidence from intervention studies that reducing drug use reduces violence. Animal and human studies provide potential biological explanations for these associations. The association between cannabis use and violence is most consistent but limited by study heterogeneity and lack of control for potential confounders. It is unclear whether these associations are causal or reflect reverse causation or the effects of confounding.

delta 1-Tetrahydrocannabinol but not cannabidiol reduces contact and aggressive behavior of rats tested in dyadic encounters

A low and a high dose of delta 1-tetrahydrocannabinol (delta 1-THC) and of cannabidiol (CBD) were IP injected in rats that had been isolated for 7 days. Forty-five minutes after injection, the rats were tested for social interactions with non-isolated, untreated test partners in dyadic encounters under standardized conditions. Different aspects of social behavior were analyzed. The high dose of delta 1-THC (10 mg/kg) prevented nearly all social interactions. The low dose of delta 1-THC (1 mg/kg) exerted selective and specific effects on social interactions. Social contact behavior, including crawl over/mounting, and social grooming, and aggressive behavior, including fighting, kicking, and biting, were markedly decreased, whereas social exploratory behavior (exploration of the partner and anogenital investigation) and the behavioral item, approach/follow, were hardly affected by delta 1-THC treatment. Both doses of CBD (2 and 20 mg/kg) failed to change the various aspects of social interaction. It is postulated that the effects of delta 1-THC on close and intimate contact behavior of rats may contribute to the understanding of marihuana taking in humans.

delta9-tetrahydrocannabinol: antiaggressive effects in mice, rats, and squirrel monkeys

delta9-Tetrahydrocannabinol, the most active constituent of marihuana, decreased species-specific attack behavior in mice, rats, and squirrel monkeys at doses (0.25 to 2.0 milligram per kilogram of body weight) that have no effects on other elements of the behavioral repertoire. Aggressive behavior was engendered in all three species by confronting a resident animal with an intruder conspecific. The present results contrast with the widely held belief that marihuana increases aggressive behavior.

Time course of delta9-tetrahydrocannabinol inhibition of predatory aggression

Three studies assessed the time course of inhibition of predatory aggression and changes in levels of brain serotonin following administration of delta9-THC. In Study One, six groups of six rats each were administered 1.25 mg/kg delta9-THC IV and frog-killing behavior was measured at six postinjection intervals: 30, 60, 90, 150, 210, and 270 minutes. In Study Two, four groups of six rats each were tested. Group One received a vehicle control injection and was tested immediately, i.e. zero-minutes, postinjection. The remaining groups received 1.25 mg/kg delta9-THC, and behavior was measured at 0, 15, and 30 min postinjection. In Study Three, two groups of six rats were treated with the vehicle or 1.25 mg/kg delta9-THC and sacrificed one minute postinjection. Additional drug groups were sacrificed at 30 and 210 min postinjection. Levels of 5-HT were determined in four brain sections: cortex, midbrain, medulla, and cerebellum. Significant inhibition of predatory aggression was found for groups tested at 0, 15, and 30 min postinjection. Brain levels of 5-HT in the midbrain and/or medulla were significantly increased over the same period.

Effects of cannabis resin on social behaviour in the laboratory mouse

The effects of several dose levels of cannabis have been studied by an ethiological analysis of encounters between male mice injected with the drug and partners injected with Tween-saline. The duration of immobility was directly related to the logarithm of the dose of cannabis given. The ratio of flight in the treated animals to aggression in those mice with which they were paired showed a progressive increase as the dose of cannabis was raised from 4-50 mg/kg. A straight line relationship was found to exist between the logarithm of flight/aggression and logarithm of the dose of cannabis administered. Non-social activity and social investigation were decreased by the administration of cannabis; this was due to the time spent by the treated animals in immobility. Aggression was not significantly altered. Many mice given doses of 25-100 mg cannabis/kg showed an ataxic gait and the Straub tail reaction.