AM251 (183232-66-8) is a potent cannabinoid CB1 receptor antagonist with selectivity over CB2 receptors (306-fold).1-3 Displays anorectic effects and antidepressant-like effects in mice.4 Behaves as an agonist at GPR55, EC50=39nM.5 Active in vivo.
1) Gatley et al. (1996), 123I-labeled AM251: a radioiodinated ligand which binds in vivo to mouse brain cannabinoid CB1 receptors; Eur. J. Pharmacol., 307 331
2) Gatley et al. (1997), Binding of the non-classical cannabinoid CP 55,940 and the diarylpyrazole AM251 to rodent brain cannabinoid receptors; Life Sci., 61 191
3) Pertwee et al. (2005), Inverse agonism and neutral antagonism at cannabinoid CB1 receptors; Life Sci., 76 1307
4) Shearman et al. (2003), Antidepressant-like and anorectic effects of the cannabinoid CB1 receptor inverse agonist AM251 in mice; behave. Pharmacol., 14 573
5) Ryberg et al. (2007), The orphan receptor GPR55 is a novel cannabinoid receptor; Br. J. Pharmacol., 152 1092