Neurophysiology and special senses: capsaicin and pain: 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 · Neurophysiology and special senses: capsaicin and pain

Sample item

Topical capsaicin cream is used for post-herpetic neuralgia. Which receptor on nociceptive C fibres does it activate, eventually depleting substance P?

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

The answer and the reasoning

D. TRPV1

Capsaicin activates TRPV1, a heat- and capsaicin-sensitive cation channel on nociceptive C fibres. Repeated application depletes substance P and desensitises the endings, which reduces pain.

Option by option

  • A. Nicotinic acetylcholine receptor

    The nicotinic receptor binds acetylcholine and is not the target of capsaicin.

  • B. Mu opioid receptor

    Mu opioid receptors bind opioids, not capsaicin.

  • C. NMDA receptor

    The NMDA receptor binds glutamate and is not the receptor for capsaicin.

  • D. TRPV1 (correct)

    Correct. Capsaicin activates the TRPV1 channel, depleting substance P with repeated use.

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, TRPV1. Capsaicin activates TRPV1, a heat- and capsaicin-sensitive cation channel on nociceptive C fibres.

Why is "Nicotinic acetylcholine receptor" not the answer?

The nicotinic receptor binds acetylcholine and is not the target of capsaicin.

Why is "Mu opioid receptor" not the answer?

Mu opioid receptors bind opioids, not capsaicin.

Why is "NMDA receptor" not the answer?

The NMDA receptor binds glutamate and is not the receptor for capsaicin.

What concept does this question test?

It tests Neurophysiology and special senses: capsaicin and pain in Physiology. Repeated application depletes substance P and desensitises the endings, which reduces pain.

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 Neurophysiology and special senses: capsaicin and pain?

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.