A schizophrenic presents with galactorrhea. The patient’s medication regimen includes haloperidol. Blockade of which neurotransmitters is responsible for this patient's clinical presentation?
Dopamine. Since it is a Prolactin Inhibitor - Inhibition of Dopamine causes hyperprolatctinemia.
Doubt: Level of dopamine also decreases in Parkinson's disease. So can hyperprolactinemia also be seen in Parkinson's disease?
In Parkinson's, there is loss of dopamine only in the substantia niagra.
There are 4 main dopaminergic pathways in the CNS:
1. Nigrostrial pathway which is involved in Parkinson's disease.
2. Mesolimbic pathway involved in Schizophrenia.
3. Paraventricular pathway involved in satiety.
4. Tuberoinfundibular pathway involved in prolactin secretion.
Drugs can affect all pathways, that's why, the side effects. But Parkinson's only hits the nigrostrial pathway.