Dopamine Receptors in Parkinson's Disease: A Meta?Analysis of Imaging Studies

Dopamine receptors are abundant along the central nigrostriatal tract and expressed as 5 subtypes in two receptor families. In PD, compensatory changes dopamine emerge a consequence of loss nerve terminals or dopaminergic pharmacotherapy. We performed systematic review meta-analysis available PET single-photon emission computed tomography studies that have investigated PSP MSA. The inclusion criteria were including human imaging; tracers (D1-like D2-like) idiopathic PSP, MSA patients compared with healthy controls. 67 included D2-like had 1925 patients. Data insufficient for an analysis D1-like studies. PD higher striatal binding early disease, but after disease duration 4.36 years, lower values than Striatal D2R was highest unmedicated striatum contralateral to predominant motor symptoms. MSA-P (14.2% 21.8%, respectively). There is initial upregulation D2Rs which downregulate on average 4 years symptom onset, possibly because agonist-induced effects. consistent symptoms indicates driven by neurodegeneration neuropil. Both clearly patients, offers opportunity differential diagnostics. © 2021 Authors. Movement Disorders published Wiley Periodicals LLC behalf International Parkinson Disorder Society