ABSTRACT
CNG channels also play a critical role in olfactory transduction (Lancet, 1986; Nakamura and Gold, 1987; Menini, 1995). Olfactory sensory neurons (OSNs) in the olfactory epithelium detect odorants via diverse G protein-coupled olfactory receptors. Olfactory receptors are coupled to Golf activation, which turns on adenylate cyclase (AC), thus leading to increased production of cAMP. Increased cAMP opens the olfactory CNG channels, which depolarize the olfactory neurons. Native olfactory CNG channels are highly permeable to Ca2+, and Ca2+ amplies olfactory signal transduction by opening Ca2+-activated chloride channels. Chloride ions owing out of the cell further depolarize the OSNs, which helps induce neurotransmitter release from olfactory receptor cells onto second-order neurons (Frings, 2001). A subset of olfactory receptor neurons utilize cGMP signaling components, including a specialized CNG channel, rather than the cAMP-based components found in the principal olfactory neurons (Meyer et al., 2000).
