Expression of cannabinoid CB₁ receptor mRNA in basal ganglia of normal and parkinsonian human brain

Reverse transcription polymerase chain reaction (RT-PCR) was used to examine the expression of the cannabinoid CB₁ receptor mRNA in post-mortem brain tissue obtained from normal subjects and patients dying with Parkinson's disease. CB₁ receptor mRNA was detected in striatal (nucleus accumbens, caudate nucleus and putamen) and extrastriatal (globus pallidus, substantia nigra) brain regions. In parkinsonian tissue the level of CB₁ receptor mRNA was decreased in the caudate nucleus, anterior dorsal putamen and external segment of the globus pallidus, but remained unchanged in the other brain areas examined. These results show that CB ₁ receptor mRNA expression was altered in Parkinson's disease (though the effects of drug treatment can not be ruled out) and indicate that cannabinoid CB₁ receptor mRNA expression was affected by alterations in dopaminergic systems.