Dopamine pathways
- Commonly altered by drugs (eg. antipsychotics) and movement disorders (eg. Parkinson disease).
- The mesocortical and mesolimbic pathways are involved in addiction behaviors.
Pathway | Projection | Function | Symtoms of altered activity | Notes |
Mesocortical | Ventral tegmental area → prefrontal cortex | Motivation and reward | Reduce activity → - symptoms | Antipsychotics have limited effect |
Mesolimbic | Ventral tegmental area → nucleus accumbens | Motivation and reward | Increase activity → + symptoms | 1° therapeutic target of antipsychotics |
Nigrostriatal | Substantia nigra → dorsal striatum | Motor control (pronounce “nigrostrideatal”) | Reduce activity → extrapyramidal symptoms | Significantly affected by antipsychotics and in Parkinson disease |
Tuberoinfundibular | Hypothalamus → pituitary | Regulation of prolactin secretion | Reduce activity → Increase prolactin | Significantly affected by antipsychotics |
- Chemoreceptor trigger zone
- Activation of DA receptors → increase emesis.
- DA agonists (e.g., apomorphine) are emetic,
- DA antagonists are antiemetic.
- Ventral tegmental area
- Is often difficult to distinguish from substantia nigra in the midbrain
- Sends dopaminergic projections to the
- Nucleus accumbens/olfactory tubercle (mesolimbic circuit),
- Prefrontal and cingulate cortex (mesocortical circuit),
- Hippocampus/amygdala.
- It is thought to play a role in reward behaviors.
Dopamine receptors
- D1-like
- Gs coupled
- D2-like
- Gi coupled 0
- D2A: nigrostriatal
- D2C: mesolimbic
The neuroleptic malignant syndrome
- A life-threatening reaction to a
- Dopamine antagonist
- Neuroleptic medication.
- Patients present with hyperthermia, cardiovascular instability, muscle rigidity, and altered mental status
- Due to enhanced sensitivity of dopamine receptors to blocking agents.
- This life-threatening condition
- Treated
See Parkinson’s
- Dopamine agonist
- Cabergoline
- Bromocriptine
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