Cysteinyl leukotrienes (LTC4, LTD4, LTE4) produced by the 5-lipoxygenase pathway mediate their bronchospastic, mucus-secreting, and eosinophil-chemotactic effects via which receptor?
- A BLT1 receptor on neutrophils
- B EP3 receptor coupled to Gi protein
- C CysLT1 receptor on airway smooth muscle, goblet cells, and eosinophils ✓
- D DP2 (CRTH2) receptor on mast cells
Correct answer: C. CysLT1 receptor on airway smooth muscle, goblet cells, and eosinophils
Explanation
Cysteinyl leukotrienes (LTC4, LTD4, LTE4) act primarily on the CysLT1 receptor, which is expressed on airway smooth muscle (causing bronchoconstriction), goblet cells (increasing mucus secretion), and eosinophils (mediating chemotaxis and tissue inflammation). Montelukast and zafirlukast block the CysLT1 receptor, providing bronchodilation and anti-inflammatory effects in asthma and allergic rhinitis. BLT1 is the LTB4 receptor on neutrophils; DP2/CRTH2 is the receptor for prostaglandin D2 involved in mast cell and Th2 responses.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
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