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

Abstract

. 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. . The effect of cannabis on mobility is a dose‐related, graded response. . Threshold doses of cannabis extract are 12·5 mg/kg when injected intravenously, and 100 mg/kg when injected intraperitoneally or subcutaneously. . 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. . 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. 1972 British Pharmacological Society