Structure activity relationship of four tetrahydrocannabinols and the pharmacological activity of five semi-purified extracts of Cannabis sativa

Effects of marihuana in laboratory animals and in man

1 The pharmacological potencies of the resins from three different samples of Brazilian marihuana (A, B and C) were determined through corneal areflexia in rabbits, decrease of spontaneous motor activity and induction of catatonia in mice, and decrease of rope climbing performance of rats.2 The Delta(9)-tetrahydrocannabinol (Delta(9) THC) content of the marihuanas, measured by gas chromatography, was 0.82, 2.02 and 0.52%, respectively, for samples A, B and C. Approximately 2% cannabinol was present in samples A and B whereas the content of cannabidiol was approximately 0.1%.3 The petroleum ether extraction of the samples A, B and C yielded, respectively, 12.06, 14.56 and 4.26% of resin.4 In all animal tests resin B was nearly twice as active as resin A, whereas C was the weakest.5 The smoke of the marihuana samples was inhaled by 33 human subjects, under a double-blind standardized procedure. Pulse rate, a time production task and an evaluation of psychological effects were recorded.6 The smoke of 250 mg of sample B provoked disruption of the time production task, increased pulse rate, and induced strong psychological reactions in four of the six subjects who received it. Similar effects, although slightly smaller, were obtained with 500 mg of sample A. On the other hand, 500 mg of sample C did not differ from placebo.7 It is suggested that it is possible by means of animal tests to predict the potency of a marihuana sample in man.8 In parallel experiments, Delta(9)-THC was administered to other human subjects and to laboratory animals in a manner similar to that in which the marihuana samples were administered.9 Comparison of the results between the marihuanas and Delta(9)-THC showed that in man and in the laboratory animals marihuanas A and B induced effects two to four times greater than expected from their Delta(9)-THC content.10 It is suggested that there may be potentiation of the effects of Delta(9)-THC by other substances present in these marihuana samples.

The ring test: a quantitative method for assessing the 'cataleptic' effect of cannabis in mice

1. A bioassay for cannabis, called the ring test, has been developed in which the percentage of the total time spent on a horizontal wire ring during which a mouse remains completely immobile is recorded.2. The effect of cannabis on mobility is a dose-related, graded response.3. Threshold doses of cannabis extract are 12.5 mg/kg when injected intravenously, and 100 mg/kg when injected intraperitoneally or subcutaneously.4. The method provides a measure of the ;cataleptic' effect of cannabis. Chlorpromazine in doses of 1 mg/kg upwards also produces the effect but barbitone does not.5. It is concluded that Delta(1)-tetrahydrocannabinol (Delta(1)-THC) is largely responsible for the effect of cannabis extract on mobility; the potency ratio of Delta(1)-THC to cannabis extract is between 10 and 20. Delta(1)-Tetrahydrocannabidivarol (Delta(1)-THD) also affects mobility but is less active than Delta(1)-THC. Cannabidiol has no effect when injected intraperitoneally in doses up to 100 mg/kg.

Factors influencing the aggressiveness elicited by marihuana in food-deprived rats

1. Aggressive behaviour was elicited in rats that had been deprived of food for 20 h daily (starved), by chronic administration of Cannabis sativa extract or (-)-Delta(9)-trans-tetrahydrocannabinol.2. The influence of intraperitoneal (i.p.) or oral glucose administration, cold environment, acidosis, and corn, and protein-free diets on this aggressiveness was studied.3. Intraperitoneal injections of glucose (100-1,600 mg/kg) did not alter the aggressiveness induced by marihuana in starved rats; glucose given orally, however, blocked this behaviour.4. Low temperature (14 degrees C) strongly potentiated the aggressive behaviour induced by marihuana in the starved rats.5. Lactic acid in doses capable of potentiating thiopental anaesthesia, failed to alter the marihuana-aggressiveness of starved rats or to facilitate this effect of marihuana in rats fed ad libitum. The same negative results were obtained with ammonium chloride.6. In rats fed ad libitum with protein-free or corn diets, marihuana administered chronically did not elicit aggressive behaviour. However, aggressiveness appeared when rats were fed for only 2 h daily on those diets.7. The results suggest that the stress of hunger (and not hypoglycaemia, acidosis or lack of specific nutrients due to starvation) is the factor that facilitates the development of aggressive behaviour by chronic administration of marihuana.