Olfactory receptor neurons transduce odorant binding through which second messenger pathway?

• A Odorant-gated chloride channels open directly, hyperpolarising the neuron
• B Transducin activates phosphodiesterase, lowering cGMP and closing ion channels
• C Gustducin raises IP3, releasing calcium from intracellular stores
• D Golf stimulates adenylyl cyclase, raising cAMP, which opens a cyclic nucleotide-gated cation channel ✓

Explanation

Olfactant receptors are GPCRs coupled to Golf, which activates adenylyl cyclase type III; rising cAMP opens a cyclic nucleotide-gated cation channel admitting sodium and calcium, depolarising the neuron. Transducin and phosphodiesterase belong to photoreceptors, and gustducin to taste cells, making B and C wrong-system traps. Calcium entering through the CNG channel subsequently opens Ca-activated chloride channels that amplify depolarisation because olfactory neurons have unusually high intracellular chloride.

Reference: Kandel Principles of Neural Science, 5th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.