In contrast to the abundance of information available regarding the development and organization of the visual, somatosensory and auditory systems, we know relatively little about the role of the central nervous system in gustation. The experiments described in this proposal are designed to provide data that will significantly improve our understanding of gustatory function. The proposed studies are based on the following three hypotheses: 1) Morphologically defined cell types of the rat nucleus of the solitary tract (NST) differ in their response properties; 2) The dendritic synaptic architecture of NST neurons reflects the response properties of these cells; 3) Changes in gustatory sensibility during development are correlated with specific morphological changes in the NST (this hypothesis will be addressed upon the completion of studies in adult animals). We will address the first hypothesis by labeling individual physiologically-characterized NST gustatory neurons in the adult rat with the intracellular injection of horseradish peroxidase (HRP). Using computerized three dimensional reconstruction techniques, we will correlate each neuron's morphological traits with its physiological response properties. The second hypothesis will be addressed by determining the density of presynaptic terminals on the dendrites of adult gustatory neurons. Individual NST neurons will be labeled with HRP and processed for electron microscopy. Segments of the first-, second-, and third-order dendrites will be reconstructed in three dimensions and the type, location and number of synapses will be ascertained. We will begin to test the third hypothesis by employing the intracellular labeling technique in postnatal animals aged 10 days (permitting optimal contrast between the immature and adult NST). At the conclusion of the proposed funding period, we expect to have described the morphological characteristics of physiologically-defined cell types in the NST. In addition, we will have characterized the dendritic synaptology of these cells. Finally, we will have begun to determine the relationship between changes in the morphology and physiology of NST neurons in developing animals.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC001074-03
Application #
2126227
Study Section
Sensory Disorders and Language Study Section (CMS)
Project Start
1992-04-01
Project End
1995-03-31
Budget Start
1994-04-01
Budget End
1995-03-31
Support Year
3
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Henry Ford Health System
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
073134603
City
Detroit
State
MI
Country
United States
Zip Code
48202
Heck, W L; Basaraba, A M; Slusarczyk, A et al. (2003) Early GABA(A) receptor clustering during the development of the rostral nucleus of the solitary tract. J Anat 202:387-96
Heck, Wendy L; Slusarczyk, Arkadiusz; Basaraba, Ana Maria et al. (2002) Subcellular localization of GABA receptors in the central nervous system using post-embedding immunohistochemistry. Brain Res Brain Res Protoc 9:173-80
Heck, W L; Renehan, W E; Schweitzer, L (2001) Redistribution and increased specificity of GABA(B) receptors during development of the rostral nucleus of the solitary tract. Int J Dev Neurosci 19:503-15
Brown, M; Renehan, W E; Schweitzer, L (2000) Changes in GABA-immunoreactivity during development of the rostral subdivision of the nucleus of the solitary tract. Neuroscience 100:849-59
Leonard, N L; Renehan, W E; Schweitzer, L (1999) Structure and function of gustatory neurons in the nucleus of the solitary tract. IV. The morphology and synaptology of GABA-immunoreactive terminals. Neuroscience 92:151-62
Wetherton, B M; Leonard, N L; Renehan, W E et al. (1998) Structure and function of gustatory neurons in the nucleus of the solitary tract. III. Classification of terminals using cluster analysis. Biotech Histochem 73:164-73
Renehan, W E; Massey, J; Jin, Z et al. (1997) Developmental changes in the dendritic architecture of salt-sensitive neurons in the nucleus of the solitary tract. Brain Res Dev Brain Res 102:231-46
Schweitzer, L; Renehan, W E (1997) The use of cluster analysis for cell typing. Brain Res Brain Res Protoc 1:100-8
Renehan, W E; Jin, Z; Zhang, X et al. (1996) Structure and function of gustatory neurons in the nucleus of the solitary tract: II. Relationships between neuronal morphology and physiology. J Comp Neurol 367:205-21
Renehan, W E; Zhang, X; Beierwaltes, W H et al. (1995) Neurons in the dorsal motor nucleus of the vagus may integrate vagal and spinal information from the GI tract. Am J Physiol 268:G780-90

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