Dept. Anatomy

SIU School of Medicine

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Department of Anatomy

  • Anthony Huang
    Assistant Professor
    Ph.D., National Taiwan University School of Medicine
    Anatomy / Neuroscience / Chemosensory
     

      Office:  Life Science III, Room 2069
      Laboratory:  Life Science III, Room 2050
      Phone:  (618) 453-1577 / 453-1532
      E-mail:  ahuang@siumed.edu 

 


Research objectives
    The sensations of taste, which are divisible into several distinct qualities: sweet, sour, bitter, salty, umami, and possibly fatty, play an important role for accepting or rejecting food and serve to protect us from ingesting harmful substances, but also cause the behavioral preferences to some types of foods. Taste sensations begin with the stimulation of taste receptor cells located in taste buds, small clusters of specialized epithelial cells on the tongue and in the oral cavity. Taste cells release transmitters during gustatory stimulation to stimulate primary afferent sensory fibers that carry the gustatory information to the brain. We have identified several transmitters − including serotonin (5-HT), ATP, norepinephrine (NE), and gamma-aminobutyric acid (GABA) − that are secreted from taste bud cells and uncovered novel mechanisms for transmitter secretion.


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A1-2, Micrographs of isolated taste buds immunostained for serotonin (5-HT). Two immunopositive taste cells (red) are visible in this plane of focus. A3, Micrograph of a Fura2-loaded (green) biosensor cell abutted against an isolated taste bud in a living preparation. (adapted from Journal of Neuroscience (2005) 25(4): 843-847; Journal of Neuroscience (2015) 35(37): 12714-12724).

    In addition to transmitting gustatory responses to prototypic taste stimuli, taste transmitters may contribute to regulating the function of adjacent taste cells. It is now being recognized there is a significant degree of information processing in the taste buds during gustatory stimulation. We are learning that cell-to-cell communication between neighboring taste cells is a key event before signals are sent to the brain via primary sensory fibers. My lab studies functions of peripheral gustatory sensory organs -- taste buds, using sophisticated anatomical and physiological methods. We apply an innovated technique, including real-time functional calcium imaging with cellular biosensor cells, to detect the secretion of transmitters, and to examine signal processing in taste buds. We used transgenic mice expressing GFP in taste cells. This will allow us to identify specific types of taste cells, and to selectively test transmitter release from taste bud cells. For instance, we, using GAD67-GFP transgenic mice, identified GABA, which inhibits ATP secretion from adjacent Receptor (Type II) cells, secreted from Presynaptic (Type III) cells.


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GABA immunostaining of an isolated taste bud from a GAD67-GFP mouse. Many GABA immunopositive taste cells express GFP (thick arrows), but some do not (thin arrows). This latter category may be Type I cells (adapted from PLoS ONE 6(10): e25471).

Science News and Information:
Mouse Taste Cells Discriminate Sweet and Sour Tastes by Releasing Neurotransmitters

    Sensory signals from the oral cavity are carried to the brain in chemosensory fibers that contribute to chemesthesis, the general chemical sensitivity of the skin and mucus membranes in the oronasal cavities and being perceived as pungency, irritation or heat. Taste perception alterations follow condition changes in the mouth, such as temperature. For instance, the pungency of foods and beverages is likely highly influenced by the temperature at which they are consumed, their acidity, and, for beverages, their carbonation. Furthermore, electrophysiology revealed that taste perception is enhanced as the temperature of food and beverage products increases. The mechanism why/how this occurs is not fully known. Intriguingly, despite the profusion of work identifying mechanisms of chemosensation, little information has been generated regarding irritant–taste interactions. By the use cellular biosensor strategy, we reported that calcitonin gene-related peptide (CGRP), which may be released from peripheral axon terminals, modulated taste-evoked ATP secretion from taste buds, which is a key transmitter for communication from taste buds to gustatory nerves. Indeed, unambiguously, our findings suggest that the complex interplay between taste cells and chemosensory neurons may play an important role during the processing of the complex stimuli involving both spicy and tasty components.


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Double immunohistochemistry on an isolated taste bud. RCP-immunoreactive (red) taste cells (arrowheads) and SNAP25-immunoreactive (green) Presynaptic (Type III) cells (large arrow) were revealed. Some taste cells exhibit double labeling, suggesting that these Presynaptic (Type III) cells express RCP (small arrows), representing CGRP receptors. (adapted from Journal of Neuroscience (2015) 35(37): 12714-12724).

    The characterization of local transmitters and their effects in the taste bud is essential not only for basic understanding of sensory afferent excitation but also for potential clinical applications. These include development of taste modifiers for potential use in management of obesity, compliance in taking medications (particularly in pediatrics), and pharmaceutical development in the context of diminished taste sensation or ageusia (lack of taste) related to age or disease chemotherapy. Indeed, taste perceptions are altered by medications that inadvertently also act on taste bud transmitters. For example, selective serotonin reuptake inhibitors such as Prozac have known taste side effects. Nevertheless, my lab plays a pioneering role in exploring the mechanisms of taste reception, and in providing the important information for sensory processing in human health and diseases.


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Schematic drawing represents the postulated scenario of CGRP, a putative efferent transmitter, in taste buds. A, Red box represents approximate position of the taste buds in B. B, Numerous CGRP-immunoreactive nerve fibers forming a dense network (large arrows) are seen in the connective tissue core of the papilla, and fine fibers (small arrows) run within, or in close association with, taste buds (areas of dashed lines). C, Chemesthetic stimulation activates sensory afferent fibers that propagate signals centrally (double-headed arrows) and have the ability to release the stored transmitter, CGRP (orange curved arrow). The activation of the CGRP receptors triggers Presynaptic (Type III) cells to secrete 5-HT, which inhibits ATP release from Receptor (Type II) cells (black symbol). (adapted from Journal of Neuroscience (2015) 35(37): 12714-12724).

Science News and Information:
Chemesthesis Affects Taste


Recent Publications (since 2005)

Huang AY, Wu SY. (2015) Calcitonin gene-related peptide reduces taste-evoked ATP secretion from mouse taste buds. J Neurosci. 35(37):12714-12724.

Huang AY, Chen MH, Wu SY, Lu KS. (2015) Tight junctions in Gerbil von Ebner's gland: horseradish peroxidase and freeze-fracture studies. Microsc Res Tech. 78(3):213-219.

Rodriguez-Diaz R, Dando R, Huang YA, Berggren P-O, Roper SD, Caicedo A (2012) Real time detection of acetylcholine release from the human endocrine pancreas. Nature Protocols 7(6):1015-1023.

Huang YA, Grant J, Roper SD (2012) Glutamate may be an efferent transmitter that elicits inhibition in mouse taste buds. PLoS ONE 7(1):e30662.

Huang YA, Pereira E, Roper SD (2011) Acid stimulation (sour taste) elicits GABA and serotonin release from mouse taste cells. PLoS ONE 6(10):e25471.

Huang YA, Stone LM, Pereira E, Yang R, Kinnamon JC, Dvoryanchikov G, Chaudhari N, Finger TE, Kinnamon SC, Roper SD (2011) Knocking out P2X receptors reduces transmitter secretion in taste buds. J Neurosci. 31(38): 13654-13661.

Dvoryanchikov G*, Huang YA*, Barro-Soria R, Chaudhari N, Roper SD (2011) GABA, its receptors, and GABAergic inhibition in mouse taste buds. J Neurosci. 31(15):5782-5791. * These authors contributed equally.

Huang YA, Roper SD (2010) Intracellular Ca2+ and TRPM5-mediated membrane depolarization produce ATP secretion from taste receptor cells. J Physiol. 588(13):2343-2350.

Huang YA, Dando RP, Roper SD (2009) Autocrine and paracrine roles of ATP and Serotonin in mouse taste buds. J Neurosci 29(44): 13909-13918.

Huang YA, Maruyama Y, Roper SD (2008) Norepinephrine is co-released with serotonin in mouse taste buds. J. Neurosci. 28(49): 13088-13093.

Huang YA, Maruyama Y, Stimac R, Roper SD (2008) Presynaptic (Type III) cells in mouse taste buds sense sour (acid) taste. J Physiol. 586: 2903-2912.

Huang YA, Maruyama Y, Dvoryanchikov G, Pereira E, Chaudhari N, Roper SD (2007) The role of pannexin 1 hemichannels in ATP release and cell-cell communication in mouse taste buds. Proc Natl Acad Sci. USA. 104(15): 6436-6441.

Huang YA, Maruyama Y, Lu KS, Pereira E, Plonsky I, Baur JE, Roper SD (2005) Mouse taste buds use serotonin as a neurotransmitter. J Neurosci. 25(4): 843-847.

Huang YA, Maruyama Y, Lu KS, Pereira E, Plonsky I, Baur JE, Roper SD (2005) Using biosensors to detect the release of serotonin from taste buds during taste stimulation. Arch Ital Biol. 143: 87-96.

Huang YA, Maruyama Y, Lu KS, Pereira E, Roper SD (2005) Mouse taste buds release serotonin in response to taste stimuli. Chem Senses Suppl 1, 30: i39-i40.