Dopamine D2 receptor

Dopamine D2 Receptor

The Dopamine D2 receptor is a critical component of the dopaminergic system, which plays a significant role in the central nervous system. It is a G protein-coupled receptor that is primarily involved in modulating neurotransmission, influencing various neurological processes, and is a target for many pharmacological agents.

Structure

The Dopamine D2 receptor is a member of the G protein-coupled receptor (GPCR) family, characterized by its seven transmembrane domains. The receptor is encoded by the DRD2 gene, which is located on chromosome 11q23.2 in humans. The receptor exists in two isoforms, D2L (long) and D2S (short), which arise from alternative splicing of the DRD2 gene.

Function

D2 receptors are primarily found in the central nervous system, particularly in the striatum, substantia nigra, and ventral tegmental area. They play a crucial role in modulating dopamine-mediated neurotransmission. The D2 receptor is involved in several physiological processes, including:

• Regulation of motor control
• Modulation of reward and reinforcement pathways
• Influence on prolactin secretion
• Impact on cognitive functions and emotional responses

Pharmacology

Dopamine D2 receptors are the primary target for many antipsychotic drugs, which are used to treat disorders such as schizophrenia and bipolar disorder. These drugs typically act as antagonists, blocking the receptor and thereby reducing dopaminergic activity. Conversely, D2 receptor agonists are used in the treatment of Parkinson's disease to enhance dopaminergic activity.

Antipsychotic Drugs

Typical antipsychotics, such as haloperidol, primarily target D2 receptors, while atypical antipsychotics, like clozapine and risperidone, have a broader spectrum of action, affecting multiple receptor types.

Parkinson's Disease

D2 receptor agonists, such as pramipexole and ropinirole, are used to alleviate symptoms of Parkinson's disease by stimulating dopamine receptors and compensating for the loss of dopaminergic neurons.

Clinical Significance

Alterations in D2 receptor function and expression have been implicated in various neuropsychiatric disorders. Overactivity of D2 receptors is associated with the positive symptoms of schizophrenia, such as hallucinations and delusions. Conversely, reduced D2 receptor activity is linked to the negative symptoms of schizophrenia and cognitive deficits.

Research

Ongoing research is focused on understanding the precise role of D2 receptors in the brain and developing more selective drugs that can modulate these receptors with fewer side effects. Studies are also exploring the genetic variations in the DRD2 gene and their association with susceptibility to psychiatric disorders.

See Also

• Dopamine receptor
• Neurotransmitter
• G protein-coupled receptor

External Links

• DRD2 gene - NCBI
• Dopamine D2 receptor - IUPHAR/BPS Guide to Pharmacology