Tuberoinfundibular Prolactin — MRCPsych Paper B MCQ

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EasySchizophrenia & PsychosisTuberoinfundibular ProlactinMRCPsych Paper B

Antipsychotic blockade of dopamine D2 receptors can remove tonic dopaminergic inhibition of prolactin secretion from the anterior pituitary. Which dopaminergic pathway mediates this effect?

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Correct answer: B — Tuberoinfundibular pathway

The correct answer is B, the tuberoinfundibular pathway. Dopamine released by hypothalamic tuberoinfundibular neurons reaches anterior pituitary lactotrophs through the hypophyseal portal circulation and tonically inhibits prolactin secretion via D2 receptors. Antipsychotic D2 receptor blockade removes this inhibition, causing hyperprolactinaemia. Mesolimbic D2 antagonism is principally associated with improvement in positive psychotic symptoms, while mesocortical dysfunction is associated with negative and cognitive symptoms. Nigrostriatal D2 blockade causes extrapyramidal adverse effects. A medullary dopaminergic pathway does not mediate the physiological inhibition of anterior pituitary prolactin secretion.

Reference: Marken PA, Haykal RF, Fisher JN. Antipsychotics: impact on prolactin levels. Annals of Pharmacotherapy. 2002;36(12):1974–1981. https://pubmed.ncbi.nlm.nih.gov/12387684/