Chemical Senses Advance Access originally published online on October 21, 2005
Chemical Senses 2005 30(9):761-769; doi:10.1093/chemse/bji068
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Taste Cell Responses in the Frog Are Modulated by Parasympathetic Efferent Nerve Fibers
1 Division of Integrative Sensory Physiology, 2 Division of Oral Cytology and Cell Biology and 3 Division of Oral Molecular Pharmacology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan
Correspondence to be sent to: Toshihide Sato, Division of Integrative Sensory Physiology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan. e-mail: toshi{at}net.nagasaki-u.ac.jp
We studied the anatomical properties of parasympathetic postganglionic neurons in the frog tongue and their modulatory effects on taste cell responses. Most of the parasympathetic ganglion cell bodies in the tongue were found in extremely small nerve bundles running near the fungiform papillae, which originate from the lingual branches of the glossopharyngeal (GP) nerve. The density of parasympathetic postganglionic neurons in the tongue was 8000–11,000/mm3 of the extremely small nerve bundle. The mean major axis of parasympathetic ganglion cell bodies was 21 µm, and the mean length of parasympathetic postganglionic neurons was 1.45 mm. Electrical stimulation at 30 Hz of either the GP nerve or the papillary nerve produced slow hyperpolarizing potentials (HPs) in taste cells. After nicotinic acetyl choline receptors on the parasympathetic ganglion cells in the tongue had been blocked by intravenous (i.v.) injection of D-tubocurarine (1 mg/kg), stimulation of the GP nerve did not induce any slow HPs in taste cells but that of the papillary nerve did. A further i.v. injection of a substance P NK-1 antagonist, L-703,606, blocked the slow HPs induced by the papillary nerve stimulation. This suggests that the parasympathetic postganglionic efferent fibers innervate taste cells and are related to a generation of the slow HPs and that substance P is released from the parasympathetic postganglionic axon terminals. When the resting membrane potential of a taste cell was hyperpolarized by a prolonged slow HP, the gustatory receptor potentials for NaCl and sugar stimuli were enhanced in amplitude, but those for quinine-HCl and acetic acid stimuli remained unchanged. It is concluded that frog taste cell responses are modulated by activities of parasympathetic postganglionic efferent fibers innervating these cells.
Key words: efferent synapse, frog taste cell, parasympathetic postganglionic neuron, slow hyperpolarizing potential, tastant-induced receptor potential
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  T. Sato, K. Nishishita, Y. Okada, and K. Toda Electrical Properties and Gustatory Responses of Various Taste Disk Cells of Frog Fungiform Papillae Chem Senses, April 1, 2008; 33(4): 371 - 378. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Eguchi, Y. Ohtubo, and K. Yoshii Functional Expression of M3, a Muscarinic Acetylcholine Receptor Subtype, in Taste Bud Cells of Mouse Fungiform Papillae Chem Senses, January 1, 2008; 33(1): 47 - 55. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Sato, K. Nishishita, Y. Okada, and K. Toda Characteristics of Biphasic Slow Depolarizing and Slow Hyperpolarizing Potential in Frog Taste Cell Induced by Parasympathetic Efferent Stimulation Chem Senses, November 1, 2007; 32(9): 817 - 823. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Sato, K. Nishishita, Y. Okada, and K. Toda Analysis of Slow Depolarizing Potential in Frog Taste Cell Induced by Parasympathetic Efferent Stimulation under Hypoxia Chem Senses, May 1, 2007; 32(4): 329 - 336. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Sato, K. Nishishita, T. Mineda, Y. Okada, and K. Toda Depression of Gustatory Receptor Potential in Frog Taste Cell by Parasympathetic Nerve-Induced Slow Hyperpolarizing Potential Chem Senses, January 1, 2007; 32(1): 3 - 10. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Sato, K. Nishishita, Y. Kato, Y. Okada, and K. Toda Tonic Activity of Parasympathetic Efferent Nerve Fibers Hyperpolarizes the Resting Membrane Potential of Frog Taste Cells Chem Senses, May 1, 2006; 31(4): 307 - 313. [Abstract] [Full Text] [PDF]
|
|