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

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Abstract
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 Δ1-tetrahydrocannabinol (Δ1-THC) is largely responsible for the effect of cannabis extract on mobility; the potency ratio of Δ1-THC to cannabis extract is between 10 and 20. Δ1-Tetrahydrocannabidivarol (Δ1-THD) also affects mobility but is less active than Δ1-THC. Cannabidiol has no effect when injected intraperitoneally in doses up to 100 mg/kg.