Regarding the effects of CB1 on neurotransmission, enhanced CB1 receptor transmission in the striatum and in the output ganglia of globus pallidus (GP) internus/substantia nigra pars reticulata may alleviate PD symptoms, whereas if CB1 is activated in GP externus, it exacerbates PD symptoms (Wang et al., 2022). This evidence concerns the gene CNR1 and Parkinson disease.