Submitted on May 15, 2007
Accepted on August 2, 2007
Highly specific olfactory receptor neurons for types of amino acids in the channel catfish
Alexander A. Nikonov1 and John Caprio1*
1 Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States
* To whom correspondence should be addressed. E-mail: jcap{at}lsu.edu.
Odorant specificity to L-
-amino acids was determined electrophysiologically for 93 single catfish olfactory receptor neurons (ORNs) selected for their narrow excitatory molecular response range (EMRR) to only one type of amino acid (i.e. Group I units). These units were excited by either a basic amino acid, a neutral amino acid with a long-side chain or a neutral amino acid with a short side-chain when tested at 10-7M - 10-5M. Stimulus-induced inhibition, likely for contrast enhancement, was primarily observed in response to the types of amino acid stimuli different from that which activated a specific ORN. The high specificity of single Group I ORNs to type of amino acid was also previously observed for single Group I neurons in both the olfactory bulb (Nikonov and Caprio, 2004) and forebrain (Nikonov and Caprio, 2007) of the same species. These results indicate that for Group I neurons olfactory information concerning specific types of amino acids is processed from receptor neurons through mitral cells of the olfactory bulb to higher forebrain neurons without significant alteration in unit odorant specificity.
