Taste receptor end-organs have long been recognized to depend upon their innervation for maintenance of their structural integrity. Indeed, taste bud degeneration following denervation is, perhaps, the most commonly cited example of neurotrophism for the sensory nervous system. Recent anatomical studies, however, have raised questions about the nature of the structural changes that occur in taste buds after interruption of the gustatory nerves. Notably, in the hamster, fungiform taste buds persist after chorda/lingual denervation although the denervated buds exhibit measurable morphological changes including atrophy and disruption of the taste pore. Apparently, the degree to which the structural integrity of taste buds depends on innervation differs dramatically between species and papillae. Factors accounting for this difference will be investigated in this project. The magnitude of taste bud degeneration following denervation might be related to the rate of cell turnover in the bud. This will be evaluated with tritiated thymidine autoradiography. Intermediate high voltage electron microscopy will establish the ultrastructural types of cells generated in denervated taste buds. The possibility that denervation may be incomplete or impermanent following gustatory nerve resection in hamsters will be evaluated with routine electron microscopy and labelling studies. The proposed labelling studies will employ injections of cholera toxin or fluorescent tracers to determine the ganglionic sources of nerve fibers that innervate taste buds before, or may innervate buds long after, chorda/lingual denervation. These studies will provide basic information concerning nerve-taste bud interactions. The studies are relevant to an understanding of how nerves maintain taste buds, and they have implications for explaining the relative vulnerability of permanence of taste compared with other sensory systems.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
1R01DC001901-01
Application #
3218471
Study Section
Sensory Disorders and Language Study Section (CMS)
Project Start
1993-04-01
Project End
1996-03-31
Budget Start
1993-04-01
Budget End
1994-03-31
Support Year
1
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Type
Schools of Medicine
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
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Zaidi, Faisal N; Todd, Krista; Enquist, Lynn et al. (2008) Types of taste circuits synaptically linked to a few geniculate ganglion neurons. J Comp Neurol 511:753-72
Ganchrow, Donald; Ganchrow, Judith R; Verdin-Alcazar, Mary et al. (2003) Brain-derived neurotrophic factor-, neurotrophin-3-, and tyrosine kinase receptor-like immunoreactivity in lingual taste bud fields of mature hamster. J Comp Neurol 455:11-24
Ganchrow, Donald; Ganchrow, Judith R; Verdin-Alcazar, Mary et al. (2003) Brain-derived neurotrophic factor-, neurotrophin-3-, and tyrosine kinase receptor-like immunoreactivity in lingual taste bud fields of mature hamster after sensory denervation. J Comp Neurol 455:25-39
Whitehead, M C; McGlathery, S T; Manion, B G (1995) Transganglionic degeneration in the gustatory system consequent to chorda tympani damage. Exp Neurol 132:239-50