Dopamine D2 receptor

The dopamine D2 receptor is a G protein-coupled receptor encoded by DRD2. It regulates neuronal signaling and is a major target of antipsychotic drugs and Parkinson’s disease treatments.

G protein-coupled receptor: A membrane receptor that activates intracellular signaling by interacting with heterotrimeric G proteins. D2 belongs to this receptor superfamily and signals through inhibitory Gi/o proteins.
Antipsychotic: A medication used chiefly to reduce psychosis, often by altering dopamine or other neurotransmitter signaling. Many antipsychotics reduce psychosis partly by blocking D2 receptor signaling.
Dopamine: A catecholamine neurotransmitter involved in movement, motivation, reward learning, and endocrine regulation. Dopamine is the endogenous ligand that activates D2 receptors.
Dopamine D1 receptor: A dopamine G protein-coupled receptor that typically stimulates adenylyl cyclase through Gs/olf proteins. D1 and D2 receptors often exert opposing effects on cyclic AMP signaling.
Nigrostriatal pathway: A dopamine pathway from the substantia nigra to the striatum that helps regulate movement. D2 receptors in this circuit mediate effects on movement and contribute to drug-induced motor symptoms.
Gi/o protein: A family of heterotrimeric G proteins that commonly inhibits adenylyl cyclase and regulates ion channels. Activated D2 receptors couple mainly to Gi/o, reducing cyclic AMP signaling.
Haloperidol: A first-generation antipsychotic medication that strongly antagonizes dopamine D2 receptors. Its D2 blockade illustrates the receptor's central role in antipsychotic action and adverse effects.
DRD2: The human gene that encodes the dopamine D2 receptor. This gene produces the receptor and its alternative splice variants.
Dopamine D3 receptor: A dopamine D2-like receptor enriched in limbic regions and implicated in reward-related behavior. D3 is a close D2-like relative with a more restricted distribution.
Mesolimbic pathway: A dopamine pathway connecting the ventral tegmental area with limbic structures, including the nucleus accumbens. D2 receptors in this pathway participate in reward learning and are implicated in psychosis.

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