D2 Receptor

Dopamine D2 receptor (D2R) provides negative-feedback control of dopamine neuron firing, dopamine synthesis, reuptake, and release, making it a core regulator of dopaminergic transmission[1]. Mechanistically, D2R signaling connects Gi activation, β-arrestin recruitment, receptor trafficking, and striatal A2A-D2R-AC5 complexes that integrate adenosine and dopamine signals in striatopallidal neurons[2][3][4]. In disease models, altered D2R signaling appears in schizophrenia-related assays, DYT1 dystonia, Huntington’s disease models, Parkinson’s disease research, and substance-use-disorder biology[1][2][5][6][7]. Compared with related isoforms, D2R-short, but not D2R-long, couples to the RhoA/ROCK/cofilin pathway and contributes to striatal vulnerability to expanded huntingtin[6]. This isoform distinction is experimentally important because D2R-short also supports dopamine- and TGFβ1-mediated growth inhibition in pituitary lactotropes[8]. For research applications, D2R agonists such as quinpirole, bromocriptine, ropinirole-related ligands, and radiolabeled MCL-536 help define receptor activity, D2high states, and disease-linked signaling responses[7][9][10]. D2R antagonists including haloperidol and clozapine show concentration-dependent dopamine antagonism, while haloperidol displays stronger β-arrestin-2 inhibition than Gi antagonism under specific assay conditions[2].
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