In the current Nature Neuroscience issue Eliot Gardners group from NIDA publishes a study showing the direct involvement of the cannabinoid CB2 receptor in cocaine addiction. The story is straightforward as it seems. CB2 agonists inhibit self-administration of cocaine in rats (bless them) and antagonists blocked the effect of CB2 agonists. They also used some CB receptor KO mice to corroborate their findings ... overall, an intriguing story - Thinking about the fact that we have found a dietary full CB2 agonist (beta-caryophyllene) that is nontoxic and usually better than JWH133 I wonder ... (thinking more ... is the CB2 receptor really present in the nucleus accumbens? It seems so if we belive this fascinating study - and more than this, it seems that it could play an important role in the reward system).
From the paper by Xi et al: We found that systemic, intranasal or intra-accumbens local administration of JWH133, a selective CB2 receptor agonist, dose-dependently inhibited intravenous cocaine self-administration, cocaine-enhanced locomotion, and cocaine-enhanced accumbens extracellular dopamine in wild-type and CB1 receptor knockout (CB1(-/-), also known as Cnr1(-/-)) mice, but not in CB(2)(-/-) (Cnr2(-/-)) mice.