Predominant role of the chorda tympani nerve in the maintenance of the taste pores: the influence of gustatory denervation in ear surgery

2000 ◽  
Vol 114 (8) ◽  
pp. 576-580 ◽  
Author(s):  
Yoshimichi Ohishi ◽  
Sohtaro Komiyama ◽  
Yoshiki Shiba D.D.S
Keyword(s):  
Cross Sections ◽  
Lingual Nerve ◽  
Confocal Laser ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Predominant Role ◽  
Rhodamine Phalloidin ◽  
Ring Shape ◽  
Pore Cells

The effect on the taste pores of denervation of the chorda tympani nerve in the middle-ear cavity was studied comparing confocal laser microscopy with lingual nerve resection. Taste pore cells were stained for actin with rhodamine-phalloidin and positive fluorescence was observed as a ring shape at the transverse cross sections. Within three days after chorda tympani nerve resection the ring reaction disappeared, although the pore morphology remained intact as seen by scanning electron microscopy. On the other hand, lingual nerve resection did not induce such rapid disappearance of the ring reaction. These results suggest that the chorda tympani nerve plays a predominant role in the maintenance of actin filaments in taste pore cells.

Salivary secretion in cat submandibular gland mediated by chorda tympani afferents

1995 ◽  
Vol 268 (2) ◽  
pp. R438-R444 ◽  
Author(s):  
H. Izumi ◽  
K. Karita
Keyword(s):  
Submandibular Gland ◽  
Salivary Secretion ◽  
Lingual Nerve ◽  
Prior Treatment ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Autonomic Ganglion ◽  
Blood Flow Increase ◽  
A Site ◽  
Stimulation Of

The aim of the present study was to investigate whether the afferent traffic from the tongue mediated only via the chorda tympani nerve (CTN) can still elicit reflex salivary and vasodilator responses in the cat submandibular gland (SMG) after section of the lingual nerve proper (LNP). Electrical stimulation of the chorda lingual nerve (CLN) at a site approximately 5 mm distal to the intersection of the CLN and the SMG duct elicited salivary and vasodilator responses in the SMG in sympathectomized cats. Both responses were unaffected by section of the LNP. The optimal frequency of CLN stimulation for submandibular salivation and vasodilation was 20 Hz, regardless of whether the LNP had been cut. Prior treatment with the autonomic ganglion blocker hexamethonium (10 mg/kg iv) virtually abolished the salivation and the blood flow increase in SMG. Prior treatment with scopolamine (0.1 mg/kg iv) almost abolished the salivary secretions but had no effect on the vasodilator responses in the SMG elicited by CLN stimulation after LNP section. The mechanism underlying the reflex submandibular salivation mediated by chorda tympani afferents appears to involve parasympathetic muscarinic receptors, but the mechanism for the vasodilator response has yet to be established. These results indicate that afferent traffic passing through the CTN on CLN stimulation is importantly involved in the parasympathetic reflex secretory and vasodilator responses in the cat SMG.

Modulation of rat chorda tympani nerve activity by lingual nerve stimulation

1995 ◽  
Vol 73 (4) ◽  
pp. 1468-1483 ◽  
Author(s):  
Y. Wang ◽  
R. P. Erickson ◽  
S. A. Simon
Keyword(s):  
Surface Temperature ◽  
Taste Receptor ◽  
Lingual Nerve ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Receptor System ◽  
Axon Reflex ◽  
Subcutaneous Injections ◽  
Peptide Release ◽  
Stimulation Voltage

1. A subpopulation of lingual nerve (LN) fibers surround and/or terminate in taste buds in fungiform papillae. One possible function of these fibers is to modulate chorda tympani fiber (CT) or taste responses. To test this hypothesis, the rat LN was stimulated electrically at various voltages (to 20 V), and single- and multiunit CT responses to water-0.1 M NaCl cycles were recorded before, during, and after LN stimulation. 2. When a thermally controlled water-0.1 M NaCl stimulus cycle was applied onto the tongue's surface, the surface temperature remained constant, independent of the stimulation voltage. In the absence of a liquid stimulus, the tongue's surface temperature increased approximately 4 degrees C upon LN stimulation for voltages > or = 5 V. This temperature increase, caused by vasodilation by way of the axon reflex flare mechanism, was taken as evidence that LN stimulation induces peptide release. 3. Comparison of CT activity before LN stimulation with the activity either during or after stimulation revealed statistically significant changes in CT activity. During LN stimulation the CT activity decreased. After LN stimulation, the variability in amount of CT activity increased. 4. In rats treated postnatally with subcutaneous injections of capsaicin to reduce or eliminate polymodal nociceptors, LN stimulation did not produce increases in the tongue's surface temperature or changes in CT activity. 5. Changes in CT activity could be detected seconds after LN stimulation, suggesting that the intragemmal and/or perigemmal LN fibers modulate CT activity. 6. The physiological implications of this study suggest that CT responses to salt can be modulated by endogenous compounds (probably peptides), eating foods that activate LN responses (e.g., foods that are very acidic or contain capsaicin) may modulate taste responses, and peri- and intragemmal fibers should be considered an integral part of the taste receptor system.

scholarly journals T1R3 taste receptor is critical for sucrose but not Polycose taste

2009 ◽  
Vol 296 (4) ◽  
pp. R866-R876 ◽  
Author(s):  
Steven Zukerman ◽  
John I. Glendinning ◽  
Robert F. Margolskee ◽  
Anthony Sclafani
Keyword(s):  
Critical Role ◽  
Taste Receptor ◽  
Sweet Taste ◽  
Sucrose Preference ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Sweet Taste Receptor ◽  
Sucrose Solutions ◽  
Nerve Recordings

In addition to their well-known preference for sugars, mice and rats avidly consume starch-derived glucose polymers (e.g., Polycose). T1R3 is a component of the mammalian sweet taste receptor that mediates the preference for sugars and artificial sweeteners in mammals. We examined the role of the T1R3 receptor in the ingestive response of mice to Polycose and sucrose. In 60-s two-bottle tests, knockout (KO) mice preferred Polycose solutions (4–32%) to water, although their overall preference was lower than WT mice (82% vs. 94%). KO mice also preferred Polycose (0.5–32%) in 24-h two-bottle tests, although less so than WT mice at dilute concentrations (0.5–4%). In contrast, KO mice failed to prefer sucrose to water in 60-s tests. In 24-h tests, KO mice were indifferent to 0.5–8% sucrose, but preferred 16–32% sucrose; this latter result may reflect the post-oral effects of sucrose. Overall sucrose preference and intake were substantially less in KO mice than WT mice. However, when retested with 0.5–32% sucrose solutions, the KO mice preferred all sucrose concentrations, although they drank less sugar than WT mice. The experience-induced sucrose preference is attributed to a post-oral conditioned preference for the T1R3-independent orosensory features of the sugar solutions (odor, texture, T1R2-mediated taste). Chorda tympani nerve recordings revealed virtually no response to sucrose in KO mice, but a near-normal response to Polycose. These results indicate that the T1R3 receptor plays a critical role in the taste-mediated response to sucrose but not Polycose.

Glossopharyngeal nerve transection does not compromise the specificity of taste-guided sodium appetite in rats

1995 ◽  
Vol 269 (1) ◽  
pp. R215-R221 ◽  
Author(s):  
S. Markison ◽  
S. J. St John ◽  
A. C. Spector
Keyword(s):  
Salivary Glands ◽  
Drinking Behavior ◽  
Lick Rate ◽  
Glossopharyngeal Nerve ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Sodium Appetite ◽  
Response Profiles ◽  
Altered Response

The chorda tympani nerve (CT) has been shown to be critical in the sodium-specific drinking behavior of sodium-depleted rats, but the role of other gustatory nerves and the contribution of the major salivary glands remain to be elucidated. In this study, rats received either bilateral section of the CT (CTX) or the glossopharyngeal nerve (GLX), extirpation of the sublingual and submaxillary salivary glands (DSAL), or sham surgery. After recovery, rats were sodium depleted with furosemide and tested for their licking responses to 0.05 and 0.3 M NaCl, KCl, CaCl2, and NH4Cl, as well as distilled water in an automated gustometer. Rats that received GLX maintained a specific sodium appetite comparable to controls despite denervation of approximately 64% of the taste buds. In contrast, compared with control rats, CTX and DSAL rats had altered response profiles, showing much smaller differences in licking to NaCl relative to the other stimuli. This was accompanied by a substantially lower lick rate in DSAL rats, raising the possibility that general licking impairments contributed to the decreased NaCl responsiveness in these rats. These findings imply that the CT, but not the glossopharyngeal nerve, is necessary for the maintenance of normal sodium-specific, taste-guided behavior under sodium deplete conditions.

scholarly journals Saliva and other taste stimuli are important for gustatory processing of linoleic acid

2009 ◽  
Vol 297 (4) ◽  
pp. R1162-R1170 ◽  
Author(s):  
Jennifer M. Stratford ◽  
Robert J. Contreras
Keyword(s):  
Linoleic Acid ◽  
Salivary Glands ◽  
Artificial Saliva ◽  
Monosodium Glutamate ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Quinine Hydrochloride ◽  
Taste Discrimination ◽  
Saliva Production

Paradoxically, bilateral transection of the chorda tympani nerve (CTX) raises the taste discrimination threshold for the free fatty acid, linoleic acid (LA), yet the chorda tympani nerve (CT) is unresponsive to lingual application of LA alone. LA may require a background of saliva to activate taste cells, since CTX decreases saliva production through denervation of the submaxillary and sublingual salivary glands. To assess the role of saliva, we measured LA taste discrimination thresholds for animals whose submaxillary and sublingual salivary glands were removed and also recorded CT responses to LA mixed in artificial saliva. Partial desalivation shifted LA discrimination thresholds from between 5.5 and 11 μM to between 11 and 22 μM. However, this effect was not as pronounced as previously seen with CTX animals. Surprisingly, the CT was unresponsive to LA mixed with artificial saliva, suggesting that artificial saliva may lack components necessary for LA taste. Additionally, fats may primarily enhance other tastes. We previously reported that LA increases CT responses to monosodium glutamate (MSG). Thus we also recorded CT whole nerve responses to taste mixtures of LA and sodium chloride (NaCl), sucrose (SUC), citric acid (CA), or quinine hydrochloride (QHCl) in anesthetized rats. We found that LA increased CT responses to NaCl but did not alter CT responses to SUC, CA, and QHCl. Thus CT recordings either lack the sensitivity to detect small changes to SUC, CA, and QHCl or LA may affect CT responses to MSG and NaCl only, perhaps by specifically modulating gustatory processing of Na+.

The role of the chorda tympani nerve in the activation of the rat hypothalamic histaminergic system by leptin

2001 ◽  
Vol 300 (2) ◽  
pp. 107-110 ◽  
Author(s):  
Tomoko Morimoto-Ishizuka ◽  
Yumiko Yamamoto ◽  
Atsushi Yamatodani
Keyword(s):  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Histaminergic System

Photo-ionization and the electrical breakdown of gases

1953 ◽  
Vol 218 (1133) ◽  
pp. 206-223 ◽  
Keyword(s):  
Cross Sections ◽  
Electrical Breakdown ◽  
Secondary Emission ◽  
Ionization Process ◽  
Predominant Role ◽  
Quantitative Investigation ◽  
Ionization Coefficients ◽  
Photo Ionization ◽  
Molecule Interaction

A quantitative theoretical investigation is made of the role of photo-ionization of the gas in the development of ionization currents in gases under uniform fields. Using published values of the relevant absorption coefficients and atomic cross-sections, the theory is applied to the case of air, and the results then compared with those previously obtained experimentally, It is shown that photo-ionization can lead to electrical breakdown only under certain restricted conditions, which relate the ionization coefficients and atomic cross-sections for photon-molecule interaction; these restrictions are such that there must be considerable penetration of the gas by ionizing photons, and in many cases a high proportion of all the photons thus reach the cathode. It is also found that the theoretical curve for the growth of current, obtained on the assumption that photo-ionization is the only operative secondary ionization process, has the same general form as the growth curve based on the other secondary processes, e. g. secondary emission from the cathode; there are, however, significant differences in detail. This quantitative investigation supports the view that photo-ionization does not play a predominant role as a secondary ionization process leading to the electrical breakdown of air at values of p x d ~ 760 cm mm Hg in uniform fields.

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