Biochemical and pharmacological characterization of... : NeuroReport (original) (raw)
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Biochemical and pharmacological characterization of cannabinoid binding sites using [3H]SR141716A
Rhône-Poulenc Rorer, Biology/Psychiatry, CRVA, 13 Quai Jules Guesde, 94403 Vitry sur Seine, France
Abstract
This study describes the binding characteristics of cannabinoid binding sites expressed in rat cerebellar membranes using the tritiated derivative of SR141716A, the newly described cannabinoid receptor antagonist. A single population of high-affinity binding sites (_K_D = 0.59 ± 0.08 nM; _B_max = 3.86 ± 0.42 pmol mg−1 of protein) was demonstrated. Kinetic, competition and saturation experiments give similar results in terms of SR141716A affinity. δ9-tetrahydrocannabinol and the 11-hydroxy derivative competitively inhibited the specific binding of [3H]SR141716A (_K_i= 47 ± 9 and 32 ± 4 nM, respectively). The cannabinoid agonist WIN55212–2 has a 25-fold lower affinity for [3H]SR141716A than for [3H]WIN55212–2, showing that the two ligands do not recognize the cannabinoid binding site in the same fashion.
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