Chemosensory mechanisms in the vertebrate taste bud have eluded detailed analyses until recently, mainly due to the relative inaccessibility of the taste cells. A particularly important question is how signals are processed in the peripheral taste organs. Ultrastructural studies have shown that there are synapses between taste cells and gustatory axons as well as between taste cells, themselves, raising the possibility that there is synaptic processing in the taste bud. We have recently employed a new approach that will allow us to examine the microphysiology of taste cells in a relatively intact, but exposed preparation and to begin to answer these questions. This preparation consists of a thin slice of lingual epithelium, mounted in a shallow. transparent chamber in such a way that entire taste buds and their cells can be visualized in the living isolated tissue. The objective of the following proposal is to test the hypothesis that there are synaptic connections among cells in the taste bud and that the final output, activity in gustatory sensory axons, represents a complex integration of signals from several different cells within the taste bud. Thus, we propose the following specific aims for the project: 1) We propose to confirm and extend our preliminary findings suggesting that there are synaptic connections between receptor and basal cells: 2) We will examine the properties of these synaptic connections, namely their Ca-dependence, neurotransmitter type, ionic mechanisms and response to repetitive and/or prolonged activation: 3) We will determine whether synaptic connections between receptor cells and basal cells are bidirectional and/or reciprocal, as their morphology suggests. The results of these studies will provide information relevant to signal processing in chemosensory receptor organs in general, such as carotid body responses. Furthermore, the data may provide a baseline for studying the question of how taste stimuli are coded in the vertebrate taste bud.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC001238-02
Application #
3217931
Study Section
Sensory Disorders and Language Study Section (CMS)
Project Start
1991-07-01
Project End
1994-06-30
Budget Start
1992-07-01
Budget End
1993-06-30
Support Year
2
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Colorado State University-Fort Collins
Department
Type
Schools of Veterinary Medicine
DUNS #
112617480
City
Fort Collins
State
CO
Country
United States
Zip Code
80523
Ewald, D A; Roper, S D (1994) Bidirectional synaptic transmission in Necturus taste buds. J Neurosci 14:3791-804