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At least 991 records · Page 55Linked to original sources
PubMed1984

Quality-specific taste changes in multiple sclerosis.

Taste sensitivity in 79 patients with multiple sclerosis (MS) and 65 age- and sex-matched control subjects was measured with a sip-and-spit, suprathreshold scaling, magnitude estimation procedure using six concentrations each of sodium chloride, sucrose, citric acid, and quinine hydrochloride. Results were analyzed with a taste scoring system and by plotting psychophysical functions (log concentration versus log magnitude estimate) normalized to 1.0 M sucrose. Gender did not affect taste scores, but age was inversely related, so the results were analyzed by an analysis of covariance with age as the covariant. There was a significant alteration in taste sensitivity in the subjects with MS for sodium chloride and quinine hydrochloride stimuli but not for sucrose and citric acid; these results were confirmed by a separate analysis of the psychophysical functions. Some of the MS taste scores correlated with MS functional and physical disability scores. Taste sensitivity was not correlated with clinical history or presence of facial symptoms.

Humans↗
PubMed2004

Expression of GDNF and GFR alpha 1 in mouse taste bud cells.

GDNF (glial cell line-derived neurotrophic factor) affects the survival and maintenance of central and peripheral neurons. Using an immunocytochemical method, we examined whether the taste bud cells in the circumvallate papillae of normal mice expressed GDNF and its GFR alpha 1 receptor. Using double immunostaining for either of them and NCAM, PGP 9.5, or alpha-gustducin, we additionally sought to determine what type of taste bud cells expressed GDNF or GFR alpha 1, because NCAM is reported to be expressed in type-III cells, PGP 9.5, in type-III and some type-II cells, and alpha-gustducin, in some type-II cells. Normal taste bud cells expressed both GDNF and GFR alpha 1. The percentage of GDNF-immunoreactive cells among all taste bud cells was 31.63%, and that of GFR alpha 1-immunoreactive cells, 83.21%. Confocal laser scanning microscopic observations after double immunostaining showed that almost none of the GDNF-immunoreactive cells in the taste buds were reactive with anti-NCAM or anti-PGP 9.5 antibody, but could be stained with anti-alpha-gustducin antibody. On the other hand, almost all anti-PGP 9.5- or anti-alpha-gustducin-immunoreactive cells were positive for GFR alpha 1. Thus, GDNF-immunoreactive cells did not include type-III cells, but type-II cells, which are alpha-gustducin-immunoreactive; on the other hand, GFR alpha 1-immunoreactive cells included type-II and -III cells, and perhaps type-I cells. We conclude that GDNF in the type-II cells may exert trophic actions on type-I, -II, and -III taste bud cells by binding to their GFR alpha 1 receptors.

Animals↗
PubMed1981

Development of chorda tympani taste responses in rat.

To learn whether neurophysiological taste responses change during structural development of the gustatory system, we recorded from the chorda tympani nerve in rats aged 7 to 92 days after birth. Chemical stimuli applied to the anterior tongue included four monochloride salts, two acids, sucrose, and urea. Responses to all chemicals were obtained as early as 7 days postnatally. Developmental changes in salt, acid, and sucrose responses were observed. Relative to NaCl and LiCl, NH4Cl and KCl gradually decrease in effectiveness as taste stimuli; or, relative to NH4Cl and KCl, NaCl and LiCl become more effective stimuli. These changes are similar to those observed prenatally and postnatally in sheep. Also, relative to NaCl, citric acid, hydrochloric acid, and sucrose become less effective stimuli; or, NaC1 becomes more effective as a stimulus, relative to these acids and sucrose. The period of most rapid functional change overlaps a period of rapid structural change. It seems most reasonable to hypothesize that the altering taste responses reflect developmental changes in receptor membrane composition. Since the taste system is not programmed to respond in a mature manner from the moment function begins, there is ample opportunity for changing taste experience to influence the developing taste system.

Aging↗
PubMed2004

Decreased taste sensitivity in cancer patients under chemotherapy.

GOALS OF WORK: The aim of the study was to measure taste thresholds among cancer patients under chemotherapy compared to controls. PATIENTS AND METHODS: The study was performed with 110 cancer patients and 170 healthy subjects of similar age distribution were included in the study. The electrogustometric detection threshold was evaluated as the lowest current intensity perceived by the subject in three tongue sites independently with a constant current generator. MAIN RESULTS: Taste thresholds for all cancer patients demonstrated significantly higher values compared to controls. CONCLUSIONS: Cancer patients treated by chemotherapy demonstrated a temporary taste sensitivity deficit. Associated with the illness due to the treatment, this deficit explains the patients complaining of "abnormal or bad tastes", which results in food aversion and has a negative impact on nutritional status and quality of life. In order to prevent the risk of anorexia and the enhanced morbidity related to this deficit, treatment should include relevant information to the subject for anticipating objective taste modifications and a psychological follow-up during the actual change of taste quality perceptions in everyday life.

Adult↗
PubMed1982

Responsiveness of dog thalamic neurons to taste stimulation of various tongue regions.

Receptive fields of single thalamic taste neurons in dogs were studied by examining responses to stimuli representing the four basic taste qualities applied to five different regions on the tongue surface. Twenty single thalamic units responded to taste stimulation of the tongue ipsilateral to the recording site were classified into three types according to characteristics of their receptive fields. In 11 out of 20 units, the location and the size of the receptive field and the most sensitive region in the receptive field did not vary among their effective taste stimuli (type A units). In 5 units, the location and the size of the receptive field varied with taste stimulus, although the most sensitive region was common to the stimuli (type B units). In the remaining 4 units, the most sensitive region varied with taste stimulus (type C units).

Afferent Pathways↗
PubMed1987

Taste effectiveness of some D- and L-amino acids in mice.

To measure the hedonic effectiveness of some D-amino acids two-bottle preference tests were carried out on ddy mice, and subsequently conditioned taste aversion (CTA) experiments were performed to determine to what degree hedonic responses to D- and L-amino acids are related to sweet taste in mice. Mice showed preferences for D-Trp, D-His, and D-Leu over certain concentration ranges, but were behaviorally neutral to D-Ser and D-Val up to 0.1 M. The preference magnitudes for D-amino acids increased with increasing molecular weight (MW) or the bulk of the side chain. CTA experiments using 0.2 M sucrose as a conditioning stimulus and 4 D- and 6 L-amino acids as test stimuli indicated that generalization of sucrose taste became stronger with increasing MW of D-amino acids and decreasing MW of L-amino acids. There was a highly significant positive correlation between the degree of generalization of sucrose taste and the preference magnitude for D- and L-amino acids. The results indicate that preferences for D- and L-amino acids in mice result from sweet taste produced by these chemicals. Comparison of the results with the human psychophysical data reveal similarity between humans and ddy mice in taste sensitivity to amino acids.

Amino Acids↗
PubMed1993

Loss and recovery of sodium-salt taste following bilateral chorda tympani nerve crush.

The ability of the gustatory system to recover following peripheral nerve injury was investigated in adult hamsters. A conditioned taste aversion paradigm was utilized to test sodium salt-taste function after bilateral crush of the chorda tympani nerve and after nerve regeneration. Bilateral chorda tympani crush abolished expression of a previously learned conditioned taste aversion to 0.1 M NaCl. At 10 to 16 weeks following surgery, the hamsters were reconditioned three times to 0.1 M NaCl. The hamsters were able to relearn the conditioned taste aversion and by 16 weeks, the crush and sham groups showed equally strong and specific aversions to 0.1 M NaCl. A second surgery to cut the regenerated chorda tympani nerves resulted, again, in the loss of expression of the conditioned taste aversion. Thus, regenerated chorda tympani nerves are capable of carrying the information needed to form a conditioned taste aversion specific for sodium salts in the adult hamster.

Animals↗
PubMed1994

Differences in taste responses to Polycose and common sugars in the rat as revealed by behavioral and electrophysiological studies.

Behavioral and electrophysiological experiments were performed to examine the suggestion that rats have two types of carbohydrate taste receptors, one for polysaccharides (e.g., Polycose) and one for common sugars (e.g., sucrose). Qualitative difference between the tastes of Polycose and sugars including sucrose, maltose, glucose, and fructose was surveyed by means of a conditioned taste aversion paradigm in which the number of licks for 20 s to each taste stimulus was measured. Aversive conditioning to Polycose did not generalize to sugars, while aversive conditioning to sucrose generalized to other sugars, but not to Polycose. In the electrophysiological study, taste responses of the whole chorda tympani were recorded. A proteolytic enzyme, pronase E, suppressed nerve responses to both Polycose and sugars to less than 50%. A novel anti-sweet peptide, gurmarin, strongly suppressed responses to sugars, but had essentially no effect on Polycose responses. On the other hand, KHCO3 enhanced responses to sugars to about 300%, but had little effect on Polycose responses. These results have confirmed the notion that rats can differentiate the tastes between Polycose and common sugars and that rats have two types of carbohydrate receptors.

Animals↗
PubMed1994

Electrophysiological and behavioral studies of taste discrimination in the axolotl (Ambystoma mexicanum).

Electrophysiological and behavioral experiments were performed to determine whether the taste system of the aquatic salamander, axolotl, discriminates taste stimuli. Taste responses were recorded extracellularly from the glossopharyngeal nerve bundle. The behavioral responses of axolotls towards various concentrations of NaCl, KCl, citric acid, quinine-hydrochloride, and sucrose were quantified by measuring the ratio of rejection towards gel pellets, each containing either unitary stimuli or binary mixtures of these chemicals. Rejection ratios [rejection/(rejection+swallowing)] towards the unitary stimuli except sucrose increased with concentration, but were not a single function of the magnitude of neural response induced by the stimuli. Degree of rejection was different depending on the quality of taste stimuli, suggesting that information processing of taste quality occurs in axolotls. The potential of NaCl to induce positive feeding behavior (swallowing) was suggested by a reduction in the rejection ratio of quinine-tainted pellets when they were mixed with 100 mM NaCl. Differential behavioral responses to quinine and NaCl show that axolotls have the ability to discriminate the taste quality of these stimuli.

Ambystoma mexicanum↗
PubMed1994

Molecular cloning of G proteins and phosphodiesterases from rat taste cells.

To identify and characterize those proteins involved in taste transduction, we cloned G proteins and phosphodiesterases from rat taste tissue. Using degenerate primers corresponding to conserved regions of G protein alpha subunits, the polymerase chain reaction was used to amplify and clone eight distinct cDNAs: alpha i-2, alpha i-3, alpha 12, alpha 14, a(s), alpha t-rod, alpha t-cone and alpha gustducin. alpha i-3, alpha 14, alpha s, and alpha t-rod are more highly expressed in taste tissue than in the surrounding nonsensory tissue. alpha gustducin is only expressed in taste cells. Rod transducin had previously been found only in the rod cells of the retina, where it converts light stimulation of rhodopsin into activation of cGMP phosphodiesterase. The primary sequence of alpha gustducin shows striking similarities to rod transducin in the receptor interaction domain and the phosphodiesterase activation site. We propose that gustducin and transducin regulate phosphodiesterase activity in taste cells and that this may promote bitter transduction and inhibit sweet transduction. Consistent with this proposal, we cloned two types of cAMP PDE from taste tissue: dnc-1 and PDE-3.

Amino Acid Sequence↗
PubMed1995

Effects of capsaicin desensitization on taste in humans.

The desensitization effects on taste resulting from application of 100 or 10 ppm capsaicin, accompanied by daily testing of a capsaicin series (1-1000 ppm, in log steps), or the desensitization resulting from application of 100 ppm capsaicin without the daily capsaicin testing, were investigated. The taste stimuli were three concentrations each of NaCl, sucrose, citric acid, quinine and 6-n-propylthiouracil. Following either type of 100 ppm desensitization, the magnitude estimates of the two bitter tastes, in particular, and citric acid showed significant decrements. Following 10 ppm capsaicin or an ethanol control procedure, there were no such effects. Recovery was complete in 1-3 days. It seems possible that the taste decrements are due to effects on both the taste and tactile components of taste, though there is a stronger case for effects on the tactile component.

Adolescent↗
PubMed1981

Access to the cerebral cortex of extra-lingual taste inputs in the rat.

Rats with their intra-lingual taste nerves (the chorda tympani and the glossopharyngeal nerve) sectioned were trained to avoid drinking 0.5 M NaCl solution by associating NaCl drinking with subsequent LiCl poisoning. The acquired learned aversion in these rats was abolished after ablations of the neocortical area for the intra-lingual taste nerves. This result indicates that extra-lingual taste inputs from the palatine and epiglottal taste buds share the neocortical taste area with intra-lingual taste inputs.

Animals↗
PubMed1982

Long-term effects of radiotherapy on taste and salivary function in man.

The long-term effects of radiotherapy on taste and salivary function were studied in 13 patients treated by radiation 1--7 years previously for tumors of the head and neck. Taste function was quantitatively evaluated using a standard forced choice, three-stimulus-drop technique for the determination of detection and recognition thresholds and a forced-scaling technique for the determination of taste intensity responsiveness. Parotid salivary function was quantitatively evaluated by determination of flow rate and protein secretion rate. Nine of the 13 patients studied (69%) had measurable taste loss; every patient who had radiotherapy including the parotid glands had measurable salivary dysfunction. Our results demonstrate that curative courses of radiotherapy for tumours of the head and neck may result in long-term changes in taste and salivary function. From the present study, the maximum tolerance doses resulting in a 50% complication rate 5 years after treatment (TD 50/5) are estimated to be 40--65 Gy for xerostomia and 50--65 Gy for taste loss. Therefore, in a standard treatment regimen for tumors of the head and neck, with curative intent, gustatory and salivary gland tissues frequently sustain maximum tolerance injury.

Follow-Up Studies↗
PubMed2004

The sixth taste?

Five taste qualities are recognized in humans: sweet, bitter, sour, salty, and umami. Rats and some other species may also have a sixth taste. Behavioral and electrophysiological data suggest that rats can taste polysaccharides derived from starch. Furthermore, the tastes of sugars and polysaccharides appear to differ in quality. Rats also discriminate different types of polysaccharide and starch molecules. Recent studies indicate that sweet taste is mediated by a T1R2 and T1R3 receptor complex but the identity of the hypothesized polysaccharide taste receptor remains to be established.

Animals↗
PubMed2004

Biochemical analysis of saliva and taste acuity evaluation in patients with burning mouth syndrome, xerostomia and/or gustatory disturbances.

OBJECTIVE: In the current study, we performed taste and salivary analysis on patients suffering from burning mouth syndrome and xerostomia or taste disturbances. STUDY DESIGN: A total of 180 patients who complained of idiopathic burning mouth syndrome (BMS) and taste aberrations and/or xerostomia that may accompany BMS were evaluated. These patients were compared with 90 healthy, age- and sex-matched controls. Salivary flow rate, biochemical and immunological analysis and taste acuity by the forced-choice drop technique were performed for all subjects. These analyses were found to be conclusive in distinguishing controls from patients with complaints. RESULTS: The great similarity of both salivary and taste analysis in the BMS, taste aberration and xerostomia groups, which were significantly different from the results obtained in the control group, was found to be the most striking result. Higher salivary concentrations in the experimental group were consistent with a lower saliva (water) flow rate. CONCLUSION: An oral neuropathy and/or neurological transduction interruption induced by salivary compositional alterations is suggested as the possible aetiology for the complaints. This report may add an important objective diagnostic tool to the clinician treating these patients.

Adolescent↗
PubMed2005

The relationship between phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) taster status and taste thresholds for sucrose and quinine.

OBJECTIVE: The aim of this study was to investigate the relationship of taster status with taste detection and recognition thresholds for sucrose and quinine. DESIGN: Sixty-nine subjects (35 men and 34 women; mean age, 23.9+/-1.2 years) were included. Stimulus fluids were prepared, one each for phenylthiocarbamide (PTC), 6-n-propylthiouracil (PROP), sucrose and quinine HCl. In each series, successive solutions, which comprised a total of 15 grades, differed by 0.25log units of the molar concentration. Two concentrations of NaCl (0.32 and 1.0 M) were prepared. The subjects were classified as nontasters and tasters using their PTC and PROP perceptions. Tasters were classified as medium-tasters and supertasters by the ratio of perceived bitterness of above-threshold PROP relative to the perceived saltiness of NaCl (PROP ratio). Taste detection and recognition thresholds for sucrose and quinine were determined by standard two-alternative forced choice trials. A Student's t-test, a Pearson's correlation analysis and linear contrasts in a one-way analysis of variance (ANOVA) were used. RESULTS: The percentages of nontaster, medium-taster and supertaster were 13, 70 and 17%, respectively. There were no significant gender differences in the taste detection and recognition thresholds for sucrose and quinine. The threshold for PTC and PROP showed significant correlations with taste threshold for quinine. Linear contrast in one-way ANOVA showed that the greater the value of PROP ratio, the more sensitive to sweet and bitter tastes (p<0.001). CONCLUSION: The PTC and PROP taster status is closely related with taste detection and recognition thresholds for sucrose and quinine.

Adult↗
PubMed2005

Evaluation of taste sensation following tongue reconstruction by microvascular forearm free flap.

PURPOSE: The objective of this study was to examine the restoration process of taste perception in patients after reconstruction of the tongue using microvascular forearm flaps. PATIENTS AND METHODS: Twelve patients, aged 28 to 70 years with a mean of 59.6 years consisting of 9 men and 3 women, were enrolled in this study. Examination results based on the filter paper disk and whole mouth methods were evaluated on a 6-point rating scale. RESULTS: In none of the patients was it possible to detect any perception of the test tastes in the regions under the control of the chorda tympani and glossopharyngeal nerves on the reconstructed side, indicating a "nondetectable" grade 6 result. The evaluation results for the normal tongue region under the control of the chorda tympani in the patients after tongue reconstruction showed a mean grade of 4.7 for the sweet, 4.9 for the salty, 4.6 for the sour, and 4.4 for the bitter taste. Mean grade determined by the whole mouth method was 3.6 for sweet, 3.3 for salty, 3.0 for sour, and 3.6 for bitter. CONCLUSION: No taste perception was detected in the regions of the tongue reconstructed with forearm flaps. These results led us to assume that compensatory taste perception must occur in other regions of the oral cavity because none of our postsurgery patients showed any serious taste disorder.

Adult↗
PubMed2003

Long-term recordings from afferent taste fibers.

The receptor cells of taste buds have a life span of about 10 days but it is not known if response characteristics of these receptors alter during the turnover cycle. To examine taste cell responses over time, a micromachined polyimide sieve electrode array was implanted between the cut ends of the rat chorda tympani nerve, which then regenerated through the electrode array. Long-term stable recordings from regenerated single afferent fibers innervating taste buds were possible using this technique for up to 21 days. Responses to taste stimuli recorded from the same fiber changed with time. The changes occurred in both the magnitude of response and the relative response profiles to four chemical stimuli, NaCl, sucrose, HCl, and quinine HCl. These changes in response characteristics were hypothesized to result from changes in the taste receptor cells as the receptor cells turnover in the taste buds.

Action Potentials↗