Dopaminergic Pathways
Mesocortical Pathway
- Projections from ventral tegmental area to prefrontal cortex.
- Responsible for behavioral/executive function.
- Dopamine hypothesis of Schizophrenia:
- Hypodopaminergic activity in D1 receptors in this pathway produces negative symptoms in schizophrenia (eg, apathy).
Mesolimbic Pathway
- Projections from ventral tegmental area to forebrain (esp. nucleus accumbens in the basal forebrain).
- Responsible for emotional function.
- Dopamine hypothesis of Schizophrenia:
- Hyperdopaminergic activity in D2 receptors in this pathway produces positive symptoms in schizophrenia (eg, hallucinations).
Nigrostriatal Pathway
- Projections from the substantia nigra to striatum (caudate and putamen).
- Responsible for movement.
- Decreased activity from psychotropic agents produce movement abnormalities: extrapyramidal side effects (hypokinetic and hyperkinetic movement disorders).
Tuberoinfundibular pathway
- Projections from the hypothalamus to the pituitary gland.
- The origins of the pathway are classically assigned to the periventricular and arcuate (infundibular) nuclei.
- The termination within the pituitary gland is in the median eminence.
- Responsible for prolactin release: prolactin is under tonic inhibition by dopamine.
- Decreased dopamine activity from psychotropic agents reduces prolactin inhibition (disinhibits prolactin release) and results in hyperprolactinemia: gynecomastia, galactorrhea, amenorrhea, infertility, etc...