Reproduction: pulsatile GnRH and puberty: 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 · Reproduction: pulsatile GnRH and puberty

Sample item

A 7-year-old girl with central precocious puberty is treated with a long-acting GnRH agonist, after which LH and FSH fall and breast development regresses. Why does a continuously acting agonist suppress puberty?

AIt blocks oestrogen receptors in breast tissueBIt inhibits aromatase in the ovaryCContinuous receptor stimulation desensitises and downregulates gonadotroph GnRH receptors, unlike the physiological pulsesDIt directly blocks kisspeptin synthesis in the arcuate nucleus

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

The answer and the reasoning

C. Continuous receptor stimulation desensitises and downregulates gonadotroph GnRH receptors, unlike the physiological pulses

Puberty depends on pulsatile GnRH release, driven by kisspeptin neurones, which stimulates LH and FSH secretion. Continuous GnRH agonist exposure first causes a brief flare and then desensitisation and downregulation of pituitary receptors, so gonadotrophins and sex steroids fall. The same principle is used in treating prostate cancer.

Option by option

A. It blocks oestrogen receptors in breast tissue
Receptor antagonism at the breast is the action of drugs like tamoxifen.
B. It inhibits aromatase in the ovary
Aromatase inhibitors act at a different step and are not GnRH analogues.
C. Continuous receptor stimulation desensitises and downregulates gonadotroph GnRH receptors, unlike the physiological pulses (correct)
Correct. Non-pulsatile exposure desensitises the receptors.
D. It directly blocks kisspeptin synthesis in the arcuate nucleus
Agonists act at the pituitary and do not block kisspeptin synthesis.

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.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is C, Continuous receptor stimulation desensitises and downregulates gonadotroph GnRH receptors, unlike the physiological pulses. Puberty depends on pulsatile GnRH release, driven by kisspeptin neurones, which stimulates LH and FSH secretion.

Why is "It blocks oestrogen receptors in breast tissue" not the answer?

Receptor antagonism at the breast is the action of drugs like tamoxifen.

Why is "It inhibits aromatase in the ovary" not the answer?

Aromatase inhibitors act at a different step and are not GnRH analogues.

Why is "It directly blocks kisspeptin synthesis in the arcuate nucleus" not the answer?

Agonists act at the pituitary and do not block kisspeptin synthesis.

What concept does this question test?

It tests Reproduction: pulsatile GnRH and puberty in Physiology. Continuous GnRH agonist exposure first causes a brief flare and then desensitisation and downregulation of pituitary receptors, so gonadotrophins and sex steroids fall. The same principle is used in treating prostate cancer.

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 Reproduction: pulsatile GnRH and puberty?

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.