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Development and Organization of the Chemical Senses
The chemical senses, including taste, smell and trigeminal sensitivity, play an important role in social and ingestive activities of all animals. A major emphasis in my laboratory is on questions concerning the development and organization of these systems in several vertebrate models. Three major areas are under investigation at present: 1) morphology and function of solitary chemosensory cells (see Finger et al. PNAS 2003) in protection of the airways and gut, 2) the cellular organization and development of taste buds (see Finger et al, Science 2005, and 3) regulation of feeding behavior by taste and other oropharyngeal chemoreceptors.
Solitary Chemosensory Receptor Cells are situated in the respiratory epithelium of the nasal cavity and make contact with sensory fibers of the trigeminal nerve. These chemoreceptor cells utilize diverse receptor mechanisms to detect noxious substances in the incoming airstream and elicit protective reflexes such as sneezing, coughing or cessation of inspiration (apnea). We are investigating how these cells differentiate from epithelial basal cells and how they detect the presence of noxious substances.
Feeding behavior is regulated largely by gustatory cues in many vertebrates. In order for a potential foodstuff to be swallowed, it must trigger an appetitive gustatory cue. Taste buds utilize a release ATP to activate the gustatory nerves and genetic elimination of ATP receptors on the gustatory nerves results in a mouse unable to taste anything. Yet these animals maintain normal weight and can still react when they ingest certain substances. We are investigating the role of taste and non-taste chemoreceptors in the oropharynx and gut in regulation of food intake in these "tasteless" mice. We also use non-mammalian models to study central processing and transmission of taste information. Goldfish have evolved an elaborate specialization of the pharynx that is involved in sorting food from substrate (Lamb & Finger 1995; Sharp & Finger, 2002). The neuronal machinery involved in this behavior is situated in an easily accessible, laminated structure of the hindbrain. This organization is conducive to in vitro slice physiology and pharmacology as well as to in Ca++ imaging studies on synaptic transmission (Ikenaga et al. 2006) Selected Publications
Lamb, C. and T.E. Finger (1995) Gustatory Control of feeding behavior in goldfish. Physiol. & Behav. 57: 483-488. Yee, C., Yang, R., B. Böttger, T.E. Finger, and J.C. Kinnamon (2001) “Type III” cells of Rat Taste Buds: immunohistochemical and ultrastructural studies of neuron specific enolase, protein gene product 9.5 and serotonin. J. Comp. Neurol. 440: 97-108. Stone, L.M., SS Tan, P.P.L. Tam, and T.E. Finger (2002) Analysis Of Cell Lineage Relationships In Taste Buds. J. Neurosci. 22: 4522-9. Sharp, A. & T.E. Finger (2002) GABAergic Modulation of Primary Gustatory Afferent Synaptic Efficacy. J. Neurobiol. 52:133-43. Finger TE, Böttger B, Hansen A, Anderson KT, Alimohammadi H, Silver WL. (2003) Solitary chemoreceptor cells in the nasal cavity serve as sentinels of respiration. Proc Natl Acad Sci U S A. 100:8981-6. Finger TE, Danilova V, Barrows J, Bartel DL, Vigers AJ, Stone L, Hellekant G, Kinnamon SC. (2005) ATP signaling is crucial for communication from taste buds to gustatory nerves. Science 310:1495-9. Bartel, DL, Sullivan SL, Lavoie ÉG, Sévigny J, Finger TE (2006) Nucleoside Triphosphate Diphosphohydrolase-2 (NTPDase2) is the ecto-ATPase of taste buds. J Comp Neurol. 497: 1-12. Ikenaga, T, Huesa, T and Finger, TE (2006) Co-occurrence of calcium binding proteins and calcium-fluxing glutamate receptors in the primary gustatory nucleus of goldfish. J Comp Neurol. 499(1):90-105. |
Faculty
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Taste buds consist of short, neuroepithelial receptor cells embedded in gustatory epithelia, e.g. of the tongue, palate and larynx. We have shown that taste buds consist of 3 distinct differentiated cell types each serving a distinct function (Yee et al., 2001; Bartel et al, 2006). Our lineage analysis in transgenic mice, shows that taste buds arise from local epithelium and originate from a handful of epithelial progenitors (Stone et al. 2002). Our current experiments examine the role of each type of cell in detection of different taste qualities.