DRD2 and early-onset generalized limb-onset dystonia: However, in line with clinically used muscarinic 1 (M1) receptor preferring antagonists in human DYT1 dystonia, a series of ex vivo experiments in DYT1 animal models indicated a paradoxical excitation of striatal cholinergic interneurons (ChI) to normally inhibitory dopamine D2 receptor activation [3].