cAMP Assay: CHO cells expressing human CB1 or CB2 receptors are seeded 17-24 hours prior to the experiment 50.000 cells per well in a black 96 well plate with flat clear bottom (Corning Costar #3904) in DMEM (Invitrogen No. 31331), 1.times.HT supplement, with 10% fetal calf serum and incubated at 5% CO2 and 37° C. in a humidified incubator. The growth medium was exchanged with Krebs Ringer Bicarbonate buffer with 1 mM IBMX and incubated at 30.degree. C. for 30 min Compounds were added to a final assay volume of 100 ul and incubated for 30 min at 30° C. Using the cAMP-Nano-TRF detection kit the assay (Roche Diagnostics) was stopped by the addition of 50 ul lysis reagent (Tris, NaCl, 1.5% Triton X100, 2.5% NP40, 10% NaN.sub.3) and 50 ul detection solutions (20 uM mAb Alexa700-cAMP 1:1, and 48 uM Ruthenium-2-AHA-cAMP) and shaken for 2 h at room temperature. The time-resolved energy transfer is measured by a TRF reader (Evotec Technologies GmbH), equipped with a ND:YAG laser as excitation source. The plate is measured twice with the excitation at 355 nm and at the emission with a delay of 100 ns and a gate of 100 ns, total exposure time 10 s at 730 (bandwidth 30 nm) or 645 nm (bandwidth 75 nm), respectively. The FRET signal is calculated.
cAMP Assay: CHO cells expressing human CB1 or CB2 receptors are seeded 17-24 hours prior to the experiment 50.000 cells per well in a black 96 well plate with flat clear bottom (Corning Costar #3904) in DMEM (Invitrogen No. 31331), 1.times.HT supplement, with 10% fetal calf serum and incubated at 5% CO2 and 37° C. in a humidified incubator. The growth medium was exchanged with Krebs Ringer Bicarbonate buffer with 1 mM IBMX and incubated at 30.degree. C. for 30 min Compounds were added to a final assay volume of 100 ul and incubated for 30 min at 30° C. Using the cAMP-Nano-TRF detection kit the assay (Roche Diagnostics) was stopped by the addition of 50 ul lysis reagent (Tris, NaCl, 1.5% Triton X100, 2.5% NP40, 10% NaN.sub.3) and 50 ul detection solutions (20 uM mAb Alexa700-cAMP 1:1, and 48 uM Ruthenium-2-AHA-cAMP) and shaken for 2 h at room temperature. The time-resolved energy transfer is measured by a TRF reader (Evotec Technologies GmbH), equipped with a ND:YAG laser as excitation source. The plate is measured twice with the excitation at 355 nm and at the emission with a delay of 100 ns and a gate of 100 ns, total exposure time 10 s at 730 (bandwidth 30 nm) or 645 nm (bandwidth 75 nm), respectively. The FRET signal is calculated.