Anterior pituitary: prolactin regulation: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Anterior pituitary: prolactin regulation

Sample item

A 29-year-old woman on risperidone develops amenorrhoea and galactorrhoea with a raised serum prolactin and a normal pituitary scan. What is the mechanism?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Blockade of dopamine D2 receptors removes tonic inhibition of lactotrophs

Prolactin is the one anterior pituitary hormone mainly under tonic inhibitory control, by hypothalamic dopamine acting on D2 receptors of lactotrophs. Antipsychotics that block D2 receptors, or stalk compression, remove this inhibition and prolactin rises. High prolactin suppresses GnRH, causing amenorrhoea.

Option by option

  • A. Stimulation of dopamine receptors increases prolactin release

    Dopamine receptor stimulation, as with cabergoline, lowers prolactin.

  • B. Reduced oestrogen feedback on lactotrophs

    Oestrogen stimulates prolactin; reduced oestrogen would not raise it.

  • C. Direct stimulation of lactotrophs by TRH

    TRH can stimulate prolactin in primary hypothyroidism, but this does not account for the drug effect.

  • D. Blockade of dopamine D2 receptors removes tonic inhibition of lactotrophs (correct)

    Correct. Loss of dopamine inhibition raises prolactin.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is D, Blockade of dopamine D2 receptors removes tonic inhibition of lactotrophs. Prolactin is the one anterior pituitary hormone mainly under tonic inhibitory control, by hypothalamic dopamine acting on D2 receptors of lactotrophs.

Why is "Stimulation of dopamine receptors increases prolactin release" not the answer?

Dopamine receptor stimulation, as with cabergoline, lowers prolactin.

Why is "Reduced oestrogen feedback on lactotrophs" not the answer?

Oestrogen stimulates prolactin; reduced oestrogen would not raise it.

Why is "Direct stimulation of lactotrophs by TRH" not the answer?

TRH can stimulate prolactin in primary hypothyroidism, but this does not account for the drug effect.

What concept does this question test?

It tests Anterior pituitary: prolactin regulation in Physiology. Antipsychotics that block D2 receptors, or stalk compression, remove this inhibition and prolactin rises. High prolactin suppresses GnRH, causing amenorrhoea.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Anterior pituitary: prolactin regulation?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.