The effect of pretreatment with cannabidiol (CBD; 50 mg/kg i.p.) on the distribution of radioactivity in chromatograms of ethyl acetate extracts of the brains of mice injected with tritiated Δ1-tetrahydrocannabinol (3H-Δ1-THC; 1·0 mg/kg i.v.) was determined. The pretreatment with CBD produced significant increases in the levels of radioactivity in the brain assigned to Δ1-THC and its centrally active metabolite 7-hydroxy-Δ1-THC: the changes produced were respectively 1·4 and 2·0 fold.
Pretreatment with CBD did not bring about any detectable change in the degree of ‘catalepsy’ produced by Δ1-THC. This negative finding may have been due to the wide limits of error that were obtained in the bioassay.
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