TY - JOUR T1 - Correlation between Olfactory Receptor Cell Type and Function in the Channel Catfish JF - The Journal of Neuroscience JO - J. Neurosci. SP - 9328 LP - 9339 DO - 10.1523/JNEUROSCI.23-28-09328.2003 VL - 23 IS - 28 AU - Anne Hansen AU - Shane H. Rolen AU - Karl Anderson AU - Yasuhiro Morita AU - John Caprio AU - Thomas E. Finger Y1 - 2003/10/15 UR - http://www.jneurosci.org/content/23/28/9328.abstract N2 - The olfactory epithelium of fish contains three intermingled types of olfactory receptor neurons (ORNs): ciliated, microvillous, and crypt. The present experiments were undertaken to test whether the different types of ORNs respond to different classes of odorants via different families of receptor molecules and G-proteins corresponding to the morphology of the ORN. In catfish, ciliated ORNs express OR-type receptors and Gαolf. Microvillous ORNs are heterogeneous, with many expressing Gαq/11, whereas crypt ORNs express Gαo. Retrograde tracing experiments show that ciliated ORNs project predominantly to regions of the olfactory bulb (OB) that respond to bile salts (medial) and amino acids (ventral) (Nikonov and Caprio, 2001). In contrast, microvillous ORNs project almost entirely to the dorsal surface of the OB, where responses to nucleotides (posterior OB) and amino acids (anterior OB) predominate. These anatomical findings are consistent with our pharmacological results showing that forskolin (which interferes with Gαolf/cAMP signaling) blocks responses to bile salts and markedly reduces responses to amino acids. Conversely, U-73122 and U-73343 (which interfere with Gαq/11/phospholipase C signaling) diminish amino acid responses but leave bile salt and nucleotide responses essentially unchanged. In summary, our results indicate that bile salt odorants are detected predominantly by ciliated ORNs relying on the Gαolf/cAMP transduction cascade. Nucleotides are detected by microvillous ORNs using neither Gαolf/cAMP nor Gαq/11/PLC cascades. Finally, amino acid odorants activate both ciliated and microvillous ORNs but via different transduction pathways in the two types of cells. ER -