Loss of sensitivity to low concentrations of NaCl following bilateral chorda tympani nerve sections in rats

The effects of changed ionic environments on the canine taste responses to sugars were examined by recording the activity of the chorda tympani nerve. a) The responses to various sugars were greatly enhanced by the presence of salts having monovalent cations such as Na+, K+, choline+, or Tris+. The responses to sugars were suppressed by high concentrations of salts. (b) The presence of 100 mM NaCl in fructose solution did not affect the maximal response and changed the Hill constant for the concentration-response relationship from 1.3 to 2.4. (c) CaCl2 greatly enhanced the response to fructose, while MgCl2 exhibited practically no effect. The presence of 20 mM CaCl2 in fructose solution changed the Hill constant from 1.2 to 2.4. (d) CaCl2 suppressed the responses to 0.5 M sugars except for fructose and sucrose and enhanced the responses to all sugars examined at 1 M. In the glucose response, the slope of the concentration-response curve was increased by the presence of CaCl2. Here the curve in the absence of CaCl2 intersected with that in the presence of CaCl2, indicating that CaCl2 suppressed the response to glucose of low concentrations and enhanced that of high concentrations. (e) The enhancement of the sugar responses by salts was not simply explained in terms of ionic permeability at the apical membranes of taste cells. The enhanced and suppressed effects of salts on the sugar responses were interpreted in terms of the cooperativity between receptor molecules for sugars.

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Synaptic reformation between salt-sensitive taste cells and axons after denervation of mouse chorda tympani nerve and recovery of behavioral discriminability between sodium and potassium salts

Neuroscience Research ◽

10.1016/s0168-0102(00)80994-3 ◽

2000 ◽

Vol 38 ◽

pp. S24

Author(s):

K Yasumatsu

Keyword(s):

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Potassium Salts ◽

Taste Cells ◽

Sodium And Potassium

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Cell non-autonomous requirement of p75 in the development of geniculate oral sensory neurons

Scientific Reports ◽

10.1038/s41598-020-78816-y ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Tao Tang ◽

Christopher R. Donnelly ◽

Amol A. Shah ◽

Robert M. Bradley ◽

Charlotte M. Mistretta ◽

...

Keyword(s):

Sensory Neurons ◽

Significant Loss ◽

Taste Buds ◽

Neurotrophin Receptor ◽

P75 Neurotrophin Receptor ◽

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Tactile Stimuli ◽

Oral Sensory ◽

Nerve Recordings

AbstractDuring development of the peripheral taste system, oral sensory neurons of the geniculate ganglion project via the chorda tympani nerve to innervate taste buds in fungiform papillae. Germline deletion of the p75 neurotrophin receptor causes dramatic axon guidance and branching deficits, leading to a loss of geniculate neurons. To determine whether the developmental functions of p75 in geniculate neurons are cell autonomous, we deleted p75 specifically in Phox2b + oral sensory neurons (Phox2b-Cre; p75fx/fx) or in neural crest-derived cells (P0-Cre; p75fx/fx) and examined geniculate neuron development. In germline p75−/− mice half of all geniculate neurons were lost. The proportion of Phox2b + neurons, as compared to Phox2b-pinna-projecting neurons, was not altered, indicating that both populations were affected similarly. Chorda tympani nerve recordings demonstrated that p75−/− mice exhibit profound deficits in responses to taste and tactile stimuli. In contrast to p75−/− mice, there was no loss of geniculate neurons in either Phox2b-Cre; p75fx/fx or P0-Cre; p75fx/fx mice. Electrophysiological analyses demonstrated that Phox2b-Cre; p75fx/fx mice had normal taste and oral tactile responses. There was a modest but significant loss of fungiform taste buds in Phox2b-Cre; p75fx/fx mice, although there was not a loss of chemosensory innervation of the remaining fungiform taste buds. Overall, these data suggest that the developmental functions of p75 are largely cell non-autonomous and require p75 expression in other cell types of the chorda tympani circuit.

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Rate of Recovery of Taste Function after Preservation of Chorda Tympani Nerve in Middle Ear Surgery with Special Reference to Type of Disease

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348940311200111 ◽

2003 ◽

Vol 112 (1) ◽

pp. 52-56 ◽

Cited By ~ 33

Author(s):

Masafumi Sakagami ◽

Mieko Sone ◽

Keijiro Fukazawa ◽

Kojiro Tsuji ◽

Yasuo Mishiro

Keyword(s):

Recovery Of Function ◽

Inflammatory Diseases ◽

Chronic Otitis Media ◽

Normal Function ◽

Middle Ear Surgery ◽

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Taste Disturbance ◽

Postoperative Symptoms ◽

Rate Of Recovery

To study the recovery of function of the chorda tympani nerve, we examined by electrogustometry 79 patients (83 ears) with both preoperative normal function of the nerve and operative preservation of the nerve, every 2 days during hospitalization and at 6 months after surgery. For symptoms such as tongue numbness and taste disturbance, patients with noninflammmatory (NI) diseases (13/20 or 65.0%) showed a significantly higher rate of symptoms than did patients with chronic otitis media (COM; 13/35 or 37.1%) at 2 weeks after surgery (p = .032). The patients with NI diseases (5/20 or 25.0%) tended to show a higher rate of symptoms than did the COM patients (2/35 or 5.7%) or cholesteatoma patients (2/28 or 7.1%) at 6 months after surgery. The rate of recovery of the EGM threshold to normal at 2 weeks after surgery was significantly lower in NI disease patients (6/20 or 30.0%) than in COM patients (23/ 35 or 62.9%) or cholesteatoma patients (19/28 or 67.9%; p = .015 and .008, respectively). Thus, the patients with NI diseases had postoperative symptoms and elevation of EGM threshold more frequently than did the patients with inflammatory diseases.

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Chorda tympani nerve, may it have a role in stabilizing middle ear pressure?

Medical Hypotheses ◽

10.1016/j.mehy.2013.02.021 ◽

2013 ◽

Vol 80 (6) ◽

pp. 726-727 ◽

Cited By ~ 1

Author(s):

V. Rinaldi ◽

M. Cappadona ◽

M. Gaffuri ◽

S. Torretta ◽

L. Pignataro

Keyword(s):

Middle Ear ◽

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Middle Ear Pressure

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Regeneration of the Nerves in the Aerial Cavity with an Artificial Nerve Conduit -Reconstruction of Chorda Tympani Nerve Gaps-

PLoS ONE ◽

10.1371/journal.pone.0092258 ◽

2014 ◽

Vol 9 (4) ◽

pp. e92258 ◽

Cited By ~ 10

Author(s):

Toshiaki Yamanaka ◽

Hiroshi Hosoi ◽

Takayuki Murai ◽

Takehiko Kobayashi ◽

Yuji Inada ◽

...

Keyword(s):

Nerve Conduit ◽

Chorda Tympani ◽

Chorda Tympani Nerve

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Efferent Impulses in the Chorda Tympani Nerve of the Rat

Acta Physiologica Scandinavica ◽

10.1111/j.1748-1716.1971.tb05070.x ◽

1971 ◽

Vol 83 (2) ◽

pp. 203-209 ◽

Cited By ~ 18

Author(s):

Göran Hellekant

Keyword(s):

Chorda Tympani ◽

Chorda Tympani Nerve

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Amino Acids as Gustatory Stimuli in the Rat

The Journal of General Physiology ◽

10.1085/jgp.45.4.681 ◽

1962 ◽

Vol 45 (4) ◽

pp. 681-701 ◽

Cited By ~ 33

Author(s):

Bruce P. Halpern ◽

Rudy A. Bernard ◽

Morley R. Kare

Keyword(s):

Amino Acids ◽

Neural Activity ◽

Receptor Site ◽

Chorda Tympani ◽

Chorda Tympani Nerve ◽

High Concentration ◽

Low Concentration ◽

Common Receptor ◽

Amino Acid Solutions ◽

Selection Of

Neural activity in intact chorda tympani nerve of rats was studied with an electronic summator. Neural activity increased when amino acid solutions 0.01 M or above passed over the tongue. Response magnitude, at concentrations close to solubility limits for the amino acids tested, was: DL-methionine < DL-tryptophan < DL-valine < DL-alanine < glycine < 0.1 M NaCl. Maximum response magnitudes to 1 M D-, and 1.2 M DL-alanine, and 1.5 M glycine developed in 1 to 3 minutes. Following such stimulation, a 63 per cent reduction in response to 0.1 M NaCl occurred 60 minutes after the first stimulation (medians). The depression was still present 20 hours later. Responses to glycine and alanine were not depressed. Amino acids vs. water preferences were investigated. With ascending concentration sequences, rats selected low concentration DL- and L-alanine and glycine; accepted D-, L-, and DL-tryptophan and low concentration DL-methionine; and rejected high concentration glycine, DL-alanine, and DL-methionine. Descending sequences showed depressed and delayed selection of glycine and DL-alanine, and DL-methionine and D- and L-tryptophan rejection. Both groups rejected DL-valine. It is concluded that glycine and alanine receptor effects differ from those of NaCl, but that all three compounds may affect a common receptor site. Prior exposure to amino acids may modify subsequent neural and/or behavioral responses.

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