| Symbol |
DRD2 |
| Full Name |
Dopamine Receptor D2 |
| Chromosome |
11q23.2 |
| NCBI Gene |
1819 |
| Ensembl |
ENSG00000149295 |
| UniProt |
P14416 |
| Diseases |
[Parkinson's Disease](/diseases/parkinsons-disease), [Schizophrenia](/diseases/schizophrenia), [Parkinsonism](/diseases/parkinsonism) |
| Expression |
Striatum, Substantia nigra, Pituitary, [Cortex](/brain-regions/cortex) |
Drd2 Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
DRD2 (Dopamine Receptor D2) encodes the D2 dopamine receptor, a G protein-coupled receptor that inhibits adenylyl cyclase and reduces intracellular cAMP. It functions as both a presynaptic autoreceptor and postsynaptic receptor, critical for motor control, reward, and prolactin regulation.
- Gi/o coupling: Inhibits adenylyl cyclase
- Reduced cAMP: Decreases PKA activity
- Beta-arrestin pathways: G protein-independent signaling
- GIRK channel activation: Hyperpolarization through potassium channels
- PI3K/Akt pathway: Anti-apoptotic signaling
- Motor inhibition: Indirect pathway in basal ganglia
- Reward: Modulates dopaminergic tone
- Presynaptic autoreceptor: Regulates dopamine release
- Motor learning: Procedural memory formation
- Endocrine control: Prolactin inhibition
Presynaptic D2 receptors (autoreceptors):
- Located on dopamine neuron terminals
- Detect ambient dopamine levels
- Inhibit dopamine release (negative feedback)
- Regulate firing rate through somatodendritic signaling
- Lower affinity for dopamine than postsynaptic receptors
Postsynaptic D2 receptors:
- Located on indirect pathway striatal neurons
- Also on cortex, hippocampus, amygdala
- Mediate motor inhibition and reward modulation
- Different isoforms: D2S (short) and D2L (long)
- Primary therapeutic target for motor symptoms
- D2 agonists (ropinirole, pramipexole, rotigotine)
- Levodopa works through D2 receptors
- D2 receptor blockade by antipsychotics
- D2 hypersensitivity theory
- Most antipsychotics are D2 antagonists
- D2 receptors inhibit prolactin secretion
- D2 agonists treat hyperprolactinemia
- D2 receptor expression changes in AD
- Interactions with cholinergic system
- Cognitive effects of D2 modulation
- Potential for neuropsychiatric symptoms
- Early loss of D2 receptors
- Contributes to motor dysfunction
- D2 agonist trials in HD
- Loss of D2 autoreceptor function leads to excessive dopamine release
- Excitotoxic vulnerability from dysregulated neurotransmission
- Oxidative stress from dopamine metabolism
- D2 receptor internalization in PD
- Altered desensitization patterns
- Impaired receptor recycling
- D2 receptors on microglia
- Anti-inflammatory effects of D2 activation
- Therapeutic implications for PD
- Predominantly presynaptic
- Functions as autoreceptor
- Alternative splicing creates isoforms
- Predominantly postsynaptic
- Mediates motor inhibition
- Expressed in striatum
D2 receptors are the primary therapeutic target for PD motor symptoms. Several drug classes target D2 receptors:
- D2 Agonists: Ropinirole, Pramipexole, Rotigotine, Apomorphine
- Dopamine Replacement: Levodopa (converted to dopamine, activates D2)
- COMT Inhibitors: Entacapone, Opicapone (prolong levodopa effect)
Most antipsychotics work by blocking D2 receptors:
- First-generation: Haloperidol, Chlorpromazine
- Second-generation: Risperidone, Olanzapine, Quetiapine, Aripiprazole (partial agonist)
D2 agonists are first-line treatment for RLS
The D2 receptor couples to Gi/o proteins, leading to:
- Inhibition of adenylyl cyclase
- Reduced cAMP production
- Decreased PKA activity
- Reduced phosphorylation of DARPP-32
- Activation of GIRK channels → hyperpolarization
D2 receptors can signal through beta-arrestin independently of G proteins, which may contribute to:
- Receptor desensitization
- Beta-arrestin mediated MAPK activation
- Distinct behavioral effects
- D2 can form homomers
- D1-D2 heteromers have unique signaling
- Receptor-receptor interactions in disease
The "braking" pathway involves D2 receptors:
- Cortex → striatum (D2 neurons)
- D2 neurons → external globus pallidus (GPe)
- GPe inhibits subthalamic nucleus (STN)
- STN excites substantia nigra pars reticulata (SNr)
- SNr inhibits thalamus → reduced movement
- D2 neurons receive input from associative/cognitive cortices
- D2 has shorter dendritic spines
- D2 signaling reduces signal-to-noise ratio
- Loss of D2 neurons contributes to hypokinesia
- Taq1A A1 allele: Associated with reduced D2 receptor density
- C957T: Affects receptor binding affinity
- -141C Ins/Del: Alters promoter activity
- These variants may influence:
- DRD2 variants predict antipsychotic response
- Side effect profiles associated with specific alleles
- Pharmacogenomic testing for clozapine, risperidone
- Drd2 knockout mice show hyperactivity
- Impaired presynaptic regulation
- Reward deficits
- D2 overexpression: reduced locomotion
- Cre driver lines for cell-specific manipulation
- D2 agonists for PD motor symptoms
- Antipsychotic-induced hyperprolactinemia
- D2 partial agonists for schizophrenia
- Dyskinesia with long-term agonist use
- Impulse control disorders
- Sleep attacks