Figure 2.

Radioligand binding assay using CHO-K1 cells stably transfected with (A) hCB₁ and (B) hCB₂ receptors and 0.5 nM [³H]-CP55,940. The potent non-specific CB receptor ligand WIN55,212-2 was used as a positive control. Although β-amyrin displaced ∼30% at 1 µM of [³H]-CP55,940 at the CB₁ receptor, no IC₅₀ was reached at concentrations <10 µM. A racemic α,β-amyrin 1:1 mixture was assessed at 10 µM and did not exhibit significantly higher [³H]-CP55,940 displacement than the isomers tested separately (data not shown). Data show means ± SEM, n= 12 from four independent experiments.