TH and Parkinson disease: Because AR45 appears to be the predominant AR in the SNpc, it may have clinical relevance in the progressive motor disorder Parkinson’s disease (PD), resulting from the loss of TH+ neurons in the SNpc (Pike et al., 2006, 2009; Cunningham et al., 2009, 2011; Rosario et al., 2011; Holmes et al., 2013, 2016; Verdile et al., 2014).