Morphological and biochemical heterogeneity in facial and vagal nerve innervated taste buds of the channel catfish, Ictalurus punctatus
Version of Record online: 20 APR 2005
Copyright © 2005 Wiley-Liss, Inc.
Journal of Comparative Neurology
Volume 486, Issue 2, pages 132–144, 30 May 2005
How to Cite
Eram, M. and Michel, W. C. (2005), Morphological and biochemical heterogeneity in facial and vagal nerve innervated taste buds of the channel catfish, Ictalurus punctatus. J. Comp. Neurol., 486: 132–144. doi: 10.1002/cne.20543
- Issue online: 20 APR 2005
- Version of Record online: 20 APR 2005
- Manuscript Accepted: 11 JAN 2005
- Manuscript Revised: 19 MAY 2004
- Manuscript Received: 24 DEC 2003
- National Institutes of Health. Grant Numbers: DC01418, NS07938
- Willard L. Eccles Charitable Foundation
In catfish, the facial nerve innervates taste buds distributed over the entire body including the barbels, while the glossopharyngeal and vagal nerves innervate oropharyngeal taste buds. Facial nerve innervated taste buds (FITBs) are thought to be involved in food detection and localization, while glossopharyngeal and vagal nerve innervated taste buds (VITBs) evaluate the palatability of food prior to ingestion. Physiological studies indicate that both oral and extra-oral taste buds detect sapid substances such as amino acids and nucleotides, but the facial taste system is more sensitive to some of these substances. The anatomical, molecular, and/or physiological mechanisms underlying the functional differences in these two gustatory pathways remain to be identified. In the current investigation we compare the basic morphological features of FITBs and VITBs and the distribution of the following metabolites: γ-aminobutyric acid (GABA), glutamate, aspartate, alanine, taurine, and glutathione. Vagal innervated taste buds are significantly longer and narrower than FITBs, with fewer taste cells and a smaller nerve plexus. Each of the metabolites examined was heterogeneously distributed in taste cells with notably more GABA positive cells present in the VITBs. Patterns of metabolite colocalization suggest the presence of several taste cell subtypes. The morphological and metabolite differences noted between FITBs and VITBs provide a potential anatomical basis for the previously noted differences in physiological sensitivity. J. Comp. Neurol. 486:132–144, 2005. © 2005 Wiley-Liss, Inc.