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PubMed1993

Parapharyngeal space lesions syncope-syndrome. A newly proposed reflexogenic cardiovascular syndrome.

An intense vaso-vagal reaction characterizes those reflex cardiovascular syncopes in which the glossopharyngeal nerve constitutes the main afferent nerve pathway. In these syndromes, afferent fibres of the glossopharyngeal nerve project from the baroreceptorial area to the medullary cardiac and vasomotor centres, from which efferent fibres descend into the vagus. The most common reflex cardiovascular syndromes linked to the IX nerve are carotid sinus syndrome (CSS) and glossopharyngeal neuralgia-asystole syndrome (GNS). Eleven male patients (mean age 65.4 years) with recurrent and severe vaso-vagal attacks are described. The episodes were characterized by asthenia and general malaise, pallor, sudation, unrecordable or very low (40-60 mmHg) arterial blood pressure, mental disorientation and/or syncope. The admission diagnosis in these patients was CSS, but the clinical picture was quite different from classic CSS: triggering factors were not present, vasovagal episodes were longer, syncopes were more frequent and severe and VVI pacing was ineffective. Further investigation, including computerized tomography, showed in all patients a malignant or benign pathological growth occupying and compressing the parapharyngeal space. The authors think that the symptoms exhibited by their patients may be attributed to parapharyngeal space involvement. The pathogenetic mechanism of syncope in these cases could be similar to that occurring in GNS except for the absence of neuralgia itself. Surgical carotid sinus denervation or A-V sequential DDD pacing were ineffective in completely controlling symptoms. Intracranial section of the IX nerve appears to be the most effective mechanism for controlling the syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Terminal distribution of the branch termed Ramus communicans cum nervo glossopharyngeo of the facial nerve and its morphological significance.

It has already been clarified that the branch termed Ramus communicans cum nervo glossopharyngeo of the facial nerve in the current Nomina anatomica was in fact one of the branches of the glossopharyngeal nerve that ran towards the auricle [Kawai et al., 1989]. For this investigation, using 5 head sides including 3 with this branch, the author studied the course and the terminal distribution of this branch and compared the data with those of the usual vagal auricular branch which is known to be distributed into the auricle. As a result, the author confirmed that the branch in question was distributed into the cutaneous layer of the concha of the auricle and the posterior wall of the external acoustic meatus, into which the vagal auricular branch is usually distributed, and that the usual vagal or glossopharyngeal auricular branch existed simultaneously with the branch in question in 3 cases. These results suggest that this branch of the glossopharyngeal nerve does not appear simply as a compensatory branch in place of the usual vagal auricular branch.

Ear, External↗

PubMed1985

Two distinct projection areas from tongue nerves in the frontal operculum of macaque monkeys as revealed with evoked potential mapping.

Projection areas in the cerebral cortex from tongue nerves were investigated in anesthetized macaque monkeys (Macaca fuscata). Three tongue nerves (lingual nerve, chorda tympani, and a lingual branch of the glossopharyngeal nerve) were electrically stimulated and thereby evoked mass field potentials were recorded with microelectrodes roving through the exposed and buried frontal operculum. Two distinct tongue nerve projection areas were thus located; one in the lower part of the precentral gyrus ventral to the inferior precentral sulcus, and the other in the medial part of the buried frontal operculum. The former corresponds to the "cortical masticatory area", previously defined in macaque monkeys as involved in somatic sensation as well as mastication. However, the prominent projection from the chorda tympani and glossopharyngeal nerve branch, containing taste fibers, to this area suggests its involvement in taste sensation. The latter corresponds to the "pure gustatory area" defined in squirrel monkeys in both location and cytoarchitecture. However, projection to this area from the lingual nerve, which contains only somatic nerve fibers, suggests its involvement in somatic sensation, as well.

Animals↗

PubMed2004

Gustatory neural responses to umami taste stimuli in C57BL/6ByJ and 129P3/J mice.

In long-term two-bottle tests, mice from the C57BL/6ByJ (B6) strain drink more monosodium L-glutamate (MSG) and inosine-5'-monophosphate (IMP) compared with mice from the 129P3/J (129) strain. The goal of this study was to assess the role of afferent gustatory input in these strain differences. We measured integrated responses of the mouse chorda tympani and glossopharyngeal nerves to lingual application of compounds that evoke umami taste in humans: MSG, monoammonium L-glutamate (NH(4) glutamate), IMP and guanosine-5'-monophosphate (GMP) and also to other taste stimuli. Chorda tympani responses to MSG and NH(4) glutamate were similar in B6 and 129 mice. Chorda tympani responses to IMP and GMP were lower in B6 than in 129 mice. Responses to umami stimuli in the glossopharyngeal nerve did not differ between the B6 and 129 strains. Responses to MSG, IMP and GMP were not affected by sodium present in these compounds because B6 and 129 mice had similar neural taste responses to NaCl. This study has demonstrated that the increased ingestive responses to the umami stimuli in B6 mice are accompanied by either unchanged or decreased neural responses to these stimuli. Lack of support for the role of the chorda tympani or glossopharyngeal nerves in the enhanced consumption of MSG and IMP by B6 mice suggests that it is due to some other factors. Although results of our previous study suggest that postingestive effects of MSG can affect its intake, contribution of other gustatory components (e.g. greater superficial petrosal nerve or central gustatory processing) to the strain differences in consumption of umami compounds also cannot be excluded. Strain differences in gustatory neural responses to nucleotides but not glutamate suggest that these compounds may activate distinct taste transduction mechanisms.

Animals↗

PubMed1982

Role of monoamines in afferent synaptic transmission in frog taste organ.

To examine physiological and pharmacological characteristics of synaptic transmission from taste cells to afferent nerve terminals in frog taste organ, changes in the glossopharyngeal nerve discharges and responses to chemical stimulation of the tongue were examined by intra-arterially perfusing the tongue with Ringer solution containing monoamines and their related substances. Noradrenaline (NA), dopamine (DA), and adrenaline (AD) produced an increase in the spontaneous glossopharyngeal nerve discharges as well as an enhancement of taste responses to various kinds of chemical stimuli, but they did not affect tactile response. NA was the most effective of the three. Monoamine-releasing agents, tyramine and 6OHDA, enhanced spontaneous nerve discharges but depressed taste responses. Antimonoaminergic agents, phentolamine and phenoxybenzamine (alpha-blockers), increased nerve discharges and depressed taste responses, but did not affect tactile response. DCI (beta-blocker), except at high concentrations, affected neither nerve discharges nor taste responses. Pre-treatment of frogs with monoamine-depleting agents, alpha-MPT and 6OHDA, depressed taste responses. Reserpine enhanced the effect of alpha-MPT. The depressed taste responses recovered after perfusion of the tongue with NA. From the results obtained, the possibility of NA being a transmitter at the afferent synapse in the frog taste organ was discussed.

Action Potentials↗

PubMed1991

Lack of amiloride sensitivity in SHR and WKY glossopharyngeal taste responses to NaCl.

To explore possible functional strain differences in taste receptors located on the posterior tongue, we recorded electrophysiological taste responses from the glossopharyngeal nerve of spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Multifiber responses to a concentration series (0.5 M to 2.0 M) of NaCl, KCl and NH4Cl were recorded before and after lingual application of the epithelial sodium transport blocker, amiloride. Responses to a concentration series (0.0025 M to 0.1 M) of quinine hydrochloride were also recorded. When expressed relative to the 0.5-M NH4Cl response, responses to the monochloride salts were equivalent between SHR and WKY. Surprisingly, NaCl responses were not suppressed by the sodium transport blocker, amiloride. This is in direct contrast to the dramatic suppression observed in the chorda tympani. Also, relative responses to quinine were greater in the glossopharyngeal nerve of SHR than WKY. These results indicate that taste receptors innervated by the glossopharyngeal nerve lack amiloride sensitivity and that posterior taste receptor function to monochloride salts is equivalent between SHR and WKY.

Amiloride↗

PubMed1996

Sources of afferent fibers from the tongue muscles.

The afferent impulses from the tongue muscles are carried by the hypoglossal nerve, trigeminal nerve, and some of them by glossopharyngeal nerve. The main exit of afferent fibers constitutes the hypoglossal nerve. The location of the ganglion cells responsible for proprioceptive impulses are mainly in the spinal ganglia of the C1-C3 spinal nerves.

Animals↗

PubMed1996

Bilateral reflex vasodilation in the palatal mucosa evoked by unilateral tooth-pulp stimulation in the cat.

In a previous study in cats, we found that electrical stimulation of the tooth pulp caused blood flow increases at various sites in the ipsilateral oral mucosa (upper and lower gingivae, lower lip, buccal mucosa and tongue, and, notably, bilaterally in the palatal mucosa). Tooth-pulp stimulation is well-known to induce severe pain and to evoke autonomic reflex responses in other organs and tissues. The purpose of this study was: to confirm that tooth-pulp stimulation may indeed induce autonomically mediated vasodilator responses in the feline oral mucosa away from the stimulated tooth, and to test our hypothesis that the reflex pathway involves parasympathetic vasodilator fibers as efferents. Dynamic changes in palatal mucosal blood flow (PMBF), with lower lip blood flow (LBF) as a control, were investigated in anesthetized, cervically sympathectomized cats by means of Laser Doppler Flowmetry. Unilateral electrical stimulation of the maxillary canine tooth pulp produced hexamethonium-sensitive bilateral increases in PMBF in a stimulus-intensity-dependent manner, without an increase in systemic blood pressure; LBF increased only ipsilaterally. Bilateral section of the glossopharyngeal nerve roots had no effect on the vasodilator responses, while unilateral section of the facial nerve root or lesion of the pterygopalatine ganglion (PPG) abolished the response on that side. Intracranial electrical stimulation of the peripheral cut ends of the facial or glossopharyngeal nerve roots caused an increase in ipsilateral PMBF. These results indicate that unilateral tooth-pulp stimulation induces a bilateral reflex vasodilator response in the palatal mucosa mediated via parasympathetic vasodilator fibers that emerge from the brain stem with the facial nerve and reach the blood vessels via PPG. Although there is a dual innervation of the cat palatal mucosa by parasympathetic vasodilator fibers running via the facial and glossopharyngeal nerve roots, the latter are not involved in the bilateral reflex responses.

Animals↗

PubMed1978

Rapid penetration of potassium and other salts into the frog tongue papilla.

The permeabilities of the frog tongue epithelium for potassium and other ions during a short time span were investigated electrophysiologically. The fungiform papilla of the bullfrog tongue was suctioned into a U-shaped glass suction electrode, through which Ringer solution was circulated. Compound nerve action potentials were recorded antidromically from the electrode following electrical stimulation of the glossopharyngeal nerve. When more than 5-10 mM potassium salts, 30 mM RbCl, 30 mM CsCl, 0.025 g in dl solution tetrodotoxin, 0.1 g in dl solution lidocaine hydrochloride or 3 g in dl solution ethanol, each of which was dissolved in Ringer solution containing 1.9 mM KCl, were flowed through the suction electrode, only the negative components of action potentials were gradually reduced and finally disappeared. The time needed for 50% reduction of negative components was about 10 sec for 0.1 M potassium salts and longer for the nonelectrolytes. A single suctioned papilla, which was flowed with various test solutions, was stimulated electrically and the change in current threshold of the papillary nerve was measured by recording orthodromic action potentials from the glossopharyngeal nerve. The threshold decreased within 10 sec after 0.05 M BaCl2 was flowed, but increased within 10 sec after 0.1 M KCl was flowed. The reduction of negative components of nerve action potentials may be due to the conduction block induced by potassium and other ions invading to the space around axons terminals. The threshold change also may be induced by the ions reaching the axon. These results suggest that chemical substances can rapidly penetrate the tongue epithelium of the frog, reach the papillary nerve fibers and contribute or modify gustatory informations.

Action Potentials↗

PubMed2000

Leptin as a modulator of sweet taste sensitivities in mice.

Leptin acts as a potent inhibitory factor against obesity by regulating energy expenditure, food intake, and adiposity. The obese diabetic db/db mouse, which has defects in leptin receptor, displays enhanced neural responses and elevated behavioral preference to sweet stimuli. Here, we show the effects of leptin on the peripheral taste system. An administration of leptin into lean mice suppressed responses of peripheral taste nerves (chorda tympani and glossopharyngeal) to sweet substances (sucrose and saccharin) without affecting responses to sour, salty, and bitter substances. Whole-cell patch-clamp recordings of activities of taste receptor cells isolated from circumvallate papillae (innervated by the glossopharyngeal nerve) demonstrated that leptin activated outward K(+) currents, which resulted in hyperpolarization of taste cells. The db/db mouse with impaired leptin receptors showed no such leptin suppression. Taste tissue (circumvallate papilla) of lean mice expressed leptin-receptor mRNA and some of the taste cells exhibited immunoreactivities to antibodies of the leptin receptor. Taken together, these observations suggest that the taste organ is a peripheral target for leptin, and that leptin may be a sweet-sensing modulator (suppressor) that may take part in regulation of food intake. Defects in this leptin suppression system in db/db mice may lead to their enhanced peripheral neural responses and enhanced behavioral preferences for sweet substances.

Animals↗

PubMed1987

Membrane properties of glossopharyngeal sensory neurons in the petrosal ganglion of the cat.

The active and passive properties of petrosal ganglion sensory neurons with axons in the glossopharyngeal nerve were examined with intracellular microelectrodes in an in vitro preparation. Glossopharyngeal neurons could be classified into two groups: H-cells showing an inflexion or hump on the falling phase of the spike and F-cells, generating a short action potential without a hump. Most of the neurons found (85%) were H-cells. The axonal conduction velocity of both types of cells fell into the A delta range, although the average value for F-cells (13 m/s) was higher than that found for H-cells (10 m/s). H- and F-cells had similar resting membrane potentials and input resistances, but different action potential characteristics. F-cells showed a smaller action potential with a faster rate of depolarization, followed by a shorter after-hyperpolarization. The response to depolarizing current pulses applied through the microelectrode was also different in both types of cells. About half of the H-cells could not be depolarized to threshold while 85% of F-cells generated spikes. It is concluded that two different populations of petrosal ganglion neurons send axons into the glossopharyngeal nerve.

Action Potentials↗

PubMed1986

Selective depressant action of antidromic impulses on gustatory nerve signals.

The depressant action of antidromic volleys of impulses on gustatory nerve signals from the tongues of bullfrogs was studied. Electrical stimulation of the glossopharyngeal nerve at a rate of 100 Hz for 10 s and at supramaximal intensity slightly depressed the integrated glossopharyngeal nerve responses to quinine and to mechanical taps to the tongue. The same antidromic stimuli resulted in a 30-40% reduction in the responses to salt, acid, water, and warmed saline, but depressed greater than 80% of the afferent impulses firing spontaneously. The magnitude of responses to quinine and NaCl and the number of spontaneous discharges decreased gradually with an increase in either the frequency or the duration of antidromic stimuli. Similar results were obtained with intensities above the threshold for exciting gustatory and slowly adapting mechanosensitive fibers. The time required to recover from termination of the antidromic stimuli to two-thirds of the maximal amount of depression ranged between 6 and 7 min, with no significant differences among the depressions. The possible mechanisms involved in the antidromic depression of gustatory nerve signals are discussed.

Afferent Pathways↗

PubMed1981

Glossopharyngeal (vagoglossopharyngeal) neuralgia: a study of 217 cases.

In 217 cases of glossopharyngeal neuralgia seen at the Mayo Clinic between 1922 and 1977, the disease was more common in patients older than 50 years (57%), but also occurred in 43% who were between 18 and 50. Spontaneous remissions were noted by 161 patients, but 37 had no periods of pain relief. Syncope was rarely a problem. Involvement was bilateral in 12%. The combination of glossopharyngeal and trigeminal neuralgia was found in 25 patients. Positive results on the cocaine test in 112 of 125 patients aided in diagnosis. Carbamazepine is the favored medication. Early surgical experience consisted of extracranial avulsion of the glossopharyngeal nerve or intracranial section at the jugular foramen; since 1948, surgical treatment has included section of the glossopharyngeal nerve and usually the upper rootlets of the vagus nerve and additional section of the fifth cranial nerve when trigeminal neuralgia was associated. Good relief of pain was obtained surgically in 110 patients.

Adolescent↗

PubMed1995

An anterograde-retrograde labeling study of the carotid sinus nerve of the Japanese monkey (Macaca fuscata).

The sites of origin and termination of efferent and afferent fibers in the carotid sinus nerve (CSN) were investigated in the Japanese monkey. After application of a mixture of horseradish peroxidase (HRP) and wheat germ aggulutinin-conjugated HRP to the central cut end of the CSN, sensory ganglion neurons were labeled in the jugular ganglion of the vagus nerve, as well as in the superior and petrosal ganglia of the glossopharyngeal nerve. Many sympathetic ganglion neurons were also labeled retrogradely in the superior cervical ganglion. In the brain, many labeled terminals were seen ipsilaterally in the lateral division of the nucleus of the solitary tract (NST). A few neuronal cell bodies were also labeled ipsilaterally in a reticular region dorsomedial to the caudal one-third of the facial nucleus. The results indicate that the CSN of the Japanese monkey is composed mainly of afferent fibers terminating in the NST, that the afferent fibers in the CSN originate not only from the superior and petrosal ganglia of the glossopharyngeal nerve but also from the jugular ganglion of the vagus nerve, and that efferent fibers contained in the CSN arise from the medullary reticular formation and superior cervical ganglion.

Animals↗

PubMed1987

Complications in the management of large glomus jugulare tumors.

This study analyzes the complications encountered in the surgical treatment of 17 patients with large glomus jugulare tumors. All 17 patients sustained either new cranial nerve palsies or exacerbation of preexisting palsies. These involved, in descending order of frequency, the facial nerve, the vagus and glossopharyngeal nerves, and the hypoglossal nerve. Postoperative palsies of the facial nerve involved 17 patients, as compared to 5 preoperatively. Fifteen patients had postoperative partial or complete paralysis of the vagus nerve as compared to eight preoperatively. Ten patients had postoperative palsies of the hypoglossal nerve as compared to six preoperatively. Other complications included CSF leak, meningitis, and wound infection. Aspiration and dysphagia were encountered postoperatively in 13 patients. Teflon injection of paretic vocal cords and cricopharyngeal myotomy effectively improved the ability to swallow and the quality of the voice. Prompt recognition and treatment of complications is essential for effective surgical management of large glomus jugulare tumors.

Adolescent↗

PubMed1983

Morphology of the rat carotid sinus nerve. I. Course, connections, dimensions and ultrastructure.

An analysis of the morphology of the carotid sinus nerve in 39 rats revealed that the nerve emerged from the glossopharyngeal nerve (nerve IX) 0.6-1.0 mm beyond the distal extent of the petrosal ganglion. In 68% of cases the nerve consisted of a single bundle of axons; two bundles were present in the other nerves. Near the rostral pole of the carotid body, the nerve divided into multiple bundles of axons. Most axon bundles entered the carotid body, but some instead joined sympathetic nerves from the superior cervical ganglion. Some of the latter group of sinus nerve axons innervated the wall of the carotid sinus. Other presumptive baroreceptor axons reached the carotid sinus from the sinus nerve by first traversing the carotid body. The sinus nerve had an average length of 2.0 +/- 0.13 mm (mean +/- S.E.M., range = 1.3-2.9 mm, N = 15) and was elliptical in cross-section (major axis = 77 microns, minor axis = 46 microns). The nerve contained an average of 625 axons, 86% of which were unmyelinated. The perineurial sheath that enveloped the circumference of the nerve was comprised of 3 or 4 layers of cells interconnected by gap junctions and tight junctions. Near the carotid body, the perineurium extended into the nerve where it compartmentalized fascicles of axons. The endoneurium consisted mainly of collagenous fibres (mean diameter 40 nm) that were only half the size of those outside the perineurium. Endoneurial connective tissue cells were sparse, being only 5% as numerous as Schwann cells. The one blood vessel in the nerve (mean luminal diameter 12.4 +/- 1.2 microns) usually arose from vessels in nerve IX and terminated in a venule at the rostral surface of the carotid body. Ganglion cells were located in nerve IX near the origin of the sinus nerve and along the length of the sinus nerve itself. All ganglion cells examined were postsynaptic to vesicle-containing nerve terminals, and therefore were presumed to be autonomic rather than sensory. Ganglion cells were more numerous in terminal branches of the sinus nerve on the ventral surface of the carotid body. Most other ganglion cells in the carotid body were located among axons of the ganglioglomerular nerve, although some were associated with a small branch of the vagus nerve. Paraganglia were located within the sinus nerve in 15% of cases, and in another 10% of cases they were found nearby in nerve IX. The paraganglia, which measured approximately 50 X 50 X 100 microns, were innervated by axons that resembled sensory nerves of the carotid body.

Animals↗

PubMed1989

Gustatory-salivary reflex: neural activity of sympathetic and parasympathetic fibers innervating the submandibular gland of the hamster.

Electrophysiological experiments were performed to clarify the neural control mechanisms subserving gustatory-salivary reflex in anesthetized and decerebrate hamsters. Efferent neural activities of postganglionic sympathetic and preganglionic parasympathetic fibers, innervating the submandibular gland, were recorded when taste stimuli were infused into the oral cavity. Neural activities of primary gustatory afferents were also recorded from the chorda tympani (innervating the anterior part of the tongue) and the glossopharyngeal nerve (innervating the posterior part of the tongue). The parasympathetic fibers showed a low rate of spontaneous discharges (about 0.3 Hz), and responded tonically in an excitatory manner to taste stimulation. The magnitude of parasympathetic activity was highly correlated with the magnitude of gustatory afferent responses of the chorda tympani rather than that of the glossopharyngeal nerve. On the other hand, the sympathetic fibers showed irregular burst discharges (1.5 burst/s), and the rate of burst discharges was increased in response to high concentrations of HCl (0.03 M) or NaCl (1 M) solutions. Deafferentation experiments suggest that the parasympathetic activity is mainly influenced by gustatory information via the chorda tympani, while the sympathetic activity can be evoked by both the chorda tympani and glossopharyngeal nerve.

Action Potentials↗

PubMed1976

On the elicitation of the diving responses in ducks.

Peripheral receptors signalling in both the 3 main divisions of the trigeminal nerves and in the glossopharyngeal nerves are most likely involved in the onset of the apnea in diving ducks. Since the response also takes place when ducks are submerged in mercury, these peripheral receptors are hardly specific to water. Neither any of the 3 main groups of trigeminal, nor the glossopharyngeal receptors are alone responsible for the initiation of the apnea. Most likely the apnea takes place when the total impact on the 'respiratory centre' in the brain exceeds a certain treshold value, due to activation of a certain number of both trigeminal and glossopharyngeal peripheral receptors. However, even very local stimulation of the glottal area invariably evoked apnea, indicating a higher density of receptors there than for example on the beak or in the nares. This idea is supported by the fact that not even heavy rain evokes any response at all. It is unlikely that the cardiovascular adjustments displayed by diving ducks are directly coupled to the apnea response (i.e. to stimulation of peripheral receptors). Rather they are supposed to be components in orienting and chemoreceptor reflexes.

Animals↗