TABLE 1

Binding affinity (pKi), potency (pEC50), and relative efficacy (Emax) of cannabinoids in cAMP and pERK1/2 assays in CHO-hCB1R cells

Values represent the mean ± S.E.M. from at least four experiments performed in triplicate.

LigandRadioligand BindingcAMPpERK1/2
pKipEC50EmaxapEC50Emaxb
EC50 nM%EC50 nM%
CP559407.4 ± 0.28.1 ± 0.2 (7.9)82 ± 67.7 ± 0.2 (19)51 ± 2
HU-2107.7 ± 0.29.0 ± 0.2 (1.0)81 ± 57.5 ± 0.1* (31)57 ± 4
WIN55,212-26.3 ± 0.17.1 ± 0.1 (79)86 ± 47.0 ± 0.2 (107)52 ± 5
Δ9-THC6.6 ± 0.27.6 ± 0.1 (25)52 ± 56.4 ± 0.1* (371)19 ± 3
Methanandamide5.9 ± 0.16.8 ± 0.4 (158)71 ± 45.9 ± 0.1* (1230)26 ± 6
Anandamide5.5 ± 0.26.1 ± 0.2 (794)74 ± 95.5 ± 0.2 (3162)∼40
2-AG5.6 ± 0.15.9 ± 0.2 (1259)64 ± 115.8 ± 0.1 (1585)∼60
  • n = 4–6 (pKi); n = 6–8 (cAMP); n = 4–8 (pERK1/2).

  • * P < 0.05, two-way analysis of variance with Bonferroni’s multiple comparison test between changes in pEC50 values for cannabinoid ligands in cAMP versus pERK1/2 assays

  • a Percentage of maximum inhibition of forskolin response.

  • b Percentage maximum FBS response.