Category: receptor_pharmacology
Dopamine GPCRs split D1-family (D1, D5 — Gs-coupled, increase cAMP) and D2-family (D2, D3, D4 — Gi-coupled, decrease cAMP). D1 → cortical-striatal motor planning. D2 → nigrostriatal motor control + tuberoinfundibular prolactin inhibition + mesocortical/mesolimbic mood + reward. Antipsychotics (typical: high D2 affinity, EPS-prone; atypical: D2 antagonism + 5-HT2A inverse agonism, lower EPS, broader receptor profile). Partial-agonist atypicals (aripiprazole, brexpiprazole, cariprazine) self-titrate dopamine tone — partial agonism stabilizes both hypo- and hyperdopaminergic states. L-DOPA + carbidopa supplies precursor for striatal dopamine in Parkinson's (cross-link: catecholamine_synthesis upstream). Stimulants (methylphenidate, amphetamine) raise synaptic DA via DAT blockade + release. Antiemetics (metoclopramide, prochlorperazine) act at D2 in the area postrema — EPS + tardive dyskinesia tail when used chronically.