Striatal Cannabinoid CB1 Receptor mRNA Expression Is Decreased in the Reserpine-Treated Rat Model of Parkinson's Disease

High levels of both endocannabinoids and endocannabinoid receptors are present in the basal ganglia. Attention has recently focused on the role of endocannabinoids in the control of movement and in movement disorders of basal ganglia origin such as Parkinson's disease. We investigated CB1 cannabinoid receptor mRNA expression in the reserpine-treated rat model of Parkinson's disease using in situ hybridization. Reserpine treatment caused a topographically organized reduction in CB1 receptor mRNA expression in the striatum (ranging from 11.6% medially to 53.6% laterally and dorsally). No change in CB1 receptor mRNA expression was observed in the cerebral cortex or septum. This reduction in CB1 receptor mRNA expression may be secondary to increased endocannabinoid stimulation of the receptor as increased basal ganglia endocannabinoid levels have been shown to occur in this model of Parkinson's disease. The data support the idea that cannabinoid receptor antagonists may provide a useful treatment for the symptoms of Parkinson's disease.