A 28-year-old woman presents with galactorrhoea and amenorrhoea. Serum prolactin is elevated at 120 ng/mL. Prolactin secretion from lactotrophs is tonically inhibited by which hypothalamic factor?
- A Dopamine (prolactin-inhibiting factor) ✓
- B Gonadotropin-releasing hormone (GnRH)
- C Somatostatin
- D Corticotropin-releasing hormone (CRH)
Correct answer: A. Dopamine (prolactin-inhibiting factor)
Explanation
Dopamine secreted by tuberoinfundibular dopaminergic neurons tonically inhibits prolactin release from anterior pituitary lactotrophs via D2 receptors. Loss of dopaminergic inhibition (prolactinoma, dopamine antagonists) causes hyperprolactinaemia. GnRH controls gonadotropins, not prolactin. Somatostatin inhibits growth hormone and TSH.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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