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PubMed1996

Genetic diversity of PTC taste sensitivity among tribal and caste populations of Andhra Pradesh, India.

The present paper reports the variability of PTC taste sensitivity among eight endogamous tribal populations inhabiting the Eastern Ghats of North Coastal Andhra Pradesh. It was compared with the genetic diversity of PTC taste sensitivity among tribal and caste populations of Andhra Pradesh. The tribal and caste groups present a relatively high genetic diversity, of which a major proportion is due to genetic differences within populations rather than that between populations. Castes show a higher heterogeneity than tribes, the difference being significant. The high genetic diversity found among Andhra populations may be attributed to social stratification and the practice of strict endogamy.

Ethnicity↗
PubMed1998

Taste reactivity to alcohol and basic tastes in outbred mice.

The taste reactivity test was used to determine the response of outbred mice to orally infused taste solutions. For the initial measures, mice (n = 10) were tested with 3%, 6%, 9%, and 12% (v/v) alcohol and four taste solutions: sucrose, sodium chloride, hydrochloric acid, and quinine hydrochloride (a single concentration of each). A second group of naive mice (n = 16) was tested with 5%, 10%, 20%, 30%, and 40% alcohol. The final set of measures with naive mice (n = 26) was taken with a range of sucrose concentrations: 0.01 M, 0.05 M, 0.1 M, 0.5 M, and 1.0 M. In general, mice made similar reactivity responses to all solutions tested. A predominant component of the mouse response to all infused fluids was forelimb flailing; gaping was also a common response to all solutions. Despite the large number of aversive-type responses, mice rejected very little fluid via passive drip or fluid expulsion. The single, significant difference in responding to the four taste stimuli was that mice made fewer aversive responses to sucrose. Differential responding to the 5 to 40% alcohol concentrations and sucrose concentrations was observed. Mice increased ingestive responding as the concentration of alcohol and sucrose increased. Aversive responding decreased reliably only with increases in the sucrose concentration. Data provide the first reported taste reactivity responses of mice to orally infused taste solutions. These results can be compared with the extant data available in rats and can also be used as a basis for exploring taste factors in genetically defined mouse populations.

Alcohol Drinking↗
PubMed1998

Influence of PROP-sensitivity on taste perceptions and hedonics in French women. A study performed without retronasal olfaction.

Detection threshold for the taste of PROP (6-n-propyl thiouracil) in aqueous solution was determined in 173 French Caucasian women deprived of retronasal olfaction by blowing an air stream into the nostrils. As expected, the detection thresholds were bimodally distributed, although as many as 73% of the subjects had thresholds above the antimode concentration and therefore qualified as non-tasters. Detection threshold, difference threshold, intensity perceptions and preference ratings were then determined for NaCl, sucrose, caffeine, Na saccharin and naringin in 20 tasters and 20 non-tasters. No differences were found between tasters and non-tasters for detection or difference thresholds of the various tastants. Intensity and preference ratings for solutions of NaCl, saccharin or caffeine were not influenced by taster status. Although ratings of sweetness intensity for sucrose solutions did not differ between tasters and non-tasters, concentrated sucrose solutions were more disliked by non-tasters than by tasters. Non-tasters rated naringin solutions as more bitter than tasters, but naringin preference ratings were independent of taster status. Some of these findings were unexpected and further studies are required to find out whether they stem from the odour-preventing procedure or are of biological or cultural origin.

Adult↗
PubMed1998

A randomized, controlled clinical trial to evaluate the effects of zinc sulfate on cancer patients with taste alterations caused by head and neck irradiation.

BACKGROUND: In uncontrolled clinical trials, the administration of oral zinc sulfate has been reported both to prevent and correct taste abnormalities in cancer patients receiving external radiotherapy (ERT) to the head and neck region. METHODS: Eighteen patients were randomized to receive either zinc sulfate tablets (a dose of 45 mg) or placebo tablets three times a day at the onset of subjective perception of taste alterations during the course of ERT and up to 1 month after ERT termination. Taste acuity was determined by measuring detection and recognition thresholds for four taste qualities. Intolerance of zinc sulfate or placebo administration was investigated, and the oral cavity was examined. All the evaluations were studied prior to, at weekly intervals during, and 1 month after ERT administration. RESULTS: Taste acuity for one or more taste qualities was already impaired before ERT. During ERT treatment, taste alterations were experienced at least once for a minimum of 3 of the 8 measured thresholds by 100% of the patients, and 33.3% of the patients became aware of some alteration within the first week of treatment. The patients treated with placebo experienced a greater worsening of taste acuity during ERT treatment compared with those treated with zinc sulfate. One month after ERT was terminated, the patients receiving zinc sulfate had a quicker recovery of taste acuity than those receiving placebo. Statistically significant differences between the two groups emerged for urea detection and sodium chloride recognition thresholds during ERT treatment and for sodium chloride, saccharose, and hydrogen chloride recognition thresholds after the termination of ERT treatment. CONCLUSIONS: This pharmacologic therapy is effective and well tolerated; it could become a routine in clinical practice to improve the supportive care of patients with taste alterations resulting from head and neck cancer.

Administration, Oral↗
PubMed1976

How many tastes are there for low concentration "sweet" and "sour" stimuli? - Threshold implications.

Ascending series of solutions of sucrose, glucose, and citric acid were tasted and detection and recognition thresholds were noted; subjects were also required to determine the number of taste sensations that occurred and their sequence of occurrence. It was found that subjects varied in their reports of the number of taste changes and hence potential criteria for detection and recognition. Even among those subjects who reported the same number of criteria there was little consistency as to which were actually chosen for detection and recognition. Some subjects even used an intensity change rather than a quality change to signal a threshold. They criterion can thus be seen to be a potential variable in threshold measurement, and criterion-free measures of sensitivity are recommended. Taste quality descriptions were also studied and a high proportion of novel descriptions was noted; it was hypothesised that this was due to the fact that subjects were not primed with traditional descriptive terms during the instructions.

Adolescent↗
PubMed1976

Effects of lesions of the gustatory necortex on taste aversion learning in the rat.

Normal rats and rats with lesions of the gustatory neocortex (GN) were compared for their ability to learn aversions to taste cues paired with toxicosis. When the taste presentation was followed immediately by toxicosis, normal rats and rats with lesions of the posterior (visual) neocortex learned aversions to sucrose, sodium chloride, quinine hydrochloride, and hydrochloric acid solutions. Rats with GN lesions learned aversions to all solutions except sucrose. In preference tests, all solutions were shown to be discriminable from water by both normal rats and rats with GN lesions. Under conditions in which a 6-hr delay separated taste presentation and toxicosis, normal rats again learned specific aversions to all four solutions, but rats with GN lesions failed to learn specific aversions to sucrose, sodium chloride, and hydrochloric acid solutions. It was shown that the ability of rats with GN lesions to learn aversions to sucrose and quinine depended on stimulus concentration; and it was proposed that the data could be accounted for by postulating a change in the threshold for taste-illness associations following GN lesions.

Animals↗
PubMed2002

[Analysis of saccharin and aspirin tasting ability among Mongolians of Xinjiang].

The saccharin and aspirin tasting abilities have been detected and analyzed in 710 individuals (328men, 382women) of Xinjiang Mongol. It is showed that the saccharin taste-blindness ratio among Mongolians was 4.648%,frequency of the recessive gene determining taste-blindness and the dominant gene determining taste ability was 0.2156, and 0.7844 respectively,and its mean testable threshold was 8.00+/-1.34 (0.108mol/L). Distribution of aspirin tasting threshold appeared a distinct curve with double peaks and single bottom,and demonstrated the aspirin tasting ability was a monogenic character. Solution NO.7 (3.00x10(-4)mol/L) at the bottom in the curve was the boundary of taste-blindness. The peak of taste-blindness was at the solution NO.1 (1.7x10(-2)mol/L), and the peak of tasters was at the solution NO.11 (1.25x10(-5)mol/L), The ratio of aspirin taste-blindness was 90.28%. The chi2 test has been used to evaluate the statistical difference in aspirin taste-blindness ratio between male and female, the result showed that there was no significant difference (P>0.90), and the gene determining for aspirin tasting ability located on autosomes.

English Abstract↗
PubMed1989

The effect of chorda tympani section on ipsilateral and contralateral salivary secretion and taste in man.

Bilateral chorda tympani section is an accepted treatment for troublesome sialorrhoea. Nevertheless the effects of this operation have been poorly studied. Twenty patients were studied with unilateral chorda tympani section and a healthy contralateral ear. The effects on ipsilateral and contralateral stimulated submandibular and parotid flow and taste recognition and detection thresholds were measured. Stimulated submandibular flow accounted for only 27% of the total salivary flow. Chorda tympani section had no effect on submandibular flow in seven patients and only reduced submandibular flow by approximately 54% in the remaining 13 patients. No significant effect was observed on ipsilateral parotid flow rate. Electrogustometric taste detection thresholds were more than twice the accepted upper limit of normal on the lesioned side and taste recognition thresholds were also markedly abnormal. Chorda tympani section alone is a poor method of reducing stimulated salivary flow.

Adolescent↗
PubMed2006

Taste deficits related to dental deafferentation: an electrogustometric study in humans.

Dental treatments, the prevalence of which increases with age, can cause orofacial somatosensory deficits. In order to examine whether they may also affect taste sensitivity, electrogustometric thresholds were measured at 9 loci on the tongue surface in 391 healthy non-smoking, non-medicated subjects. Results showed that the greater the number of deafferented teeth, the higher the thresholds. Irrespective of age, subjects with more than 7 deafferented teeth exhibited significantly higher thresholds than subjects with fewer than 7 deafferented teeth. Conversely, across age groups, no statistical difference was observed among subjects with no, or few, deafferented teeth. Hence, a taste deficit, which was not correlated to aging, was observed. An association was noticed between the location of taste deficits and the location of deafferented teeth. Higher thresholds at anterior sites, with no possible traumatic injury relationship, suggested that neurophysiological convergence between dental somatosensory and taste pathways - possibly in the nucleus tractus solitarius - could be responsible for these relative decreases of taste sensitivity when dental afferences were lacking. Among trigeminal contributions, lingual nerve and inferior alveolar nerve may synergize taste.

Adult↗
PubMed2004

Glutamate taste: Discrimination between the tastes of glutamate agonists and monosodium glutamate in rats.

Taste aversion studies have demonstrated that rats conditioned to avoid monosodium glutamate (MSG) with amiloride added to reduce the intensity of the sodium component of MSG taste, generalize this aversion to aspartic acid and to L-AP4, but not to ionotropic glutamate receptor agonists. That is, MSG, L-AP4 and aspartate have similar tastes to rats. However, conditioned taste aversion methods are unable to show to what extent the tastes of two substances are different. If two substances activate the same afferent processes (e.g. taste receptors), they are likely to produce the same tastes, but if they activate different afferent processes, the subject may detect differences between the tastes of the substances. In this study, rats were tested to determine if they could discriminate between the tastes of these agonists and MSG. We also established the detection thresholds for NMDA, aspartic acid and L-AP4, with and without amiloride (a sodium channel antagonist). Taste threshold values were 1-4 mM for NMDA and aspartic acid and 0.5-2.5 microM for L-AP4. None were affected by 30 micro M amiloride. Rats could readily distinguish between the tastes of MSG and NMDA but they had difficulty discriminating between the tastes of aspartic acid and MSG. Rats could also easily distinguish between 10-100 mM MSG and 0.01-5 mM L-AP4. However, in two separate experiments error rates increased significantly when L-AP4 concentrations were between 10-100 mM, indicating that the tastes of L-AP4 and MSG were similar at these concentrations.

Amiloride↗
PubMed1990

Ibotenic acid lesion of the lateral hypothalamus increases preference and aversion thresholds for saccharin and alters the morphine modulation of taste.

In a previous study we showed that bilateral ibotenic acid lesions of the lateral hypothalamus in rats induced an increase in gustatory preference thresholds for saccharin solutions and which were associated with body weight and daily water intake impairments. The first aim of the present study was an attempt to dissociate the body weight and water intake deficits from the increase in gustatory thresholds. For this purpose we compared the effect of simultaneous bilateral lesions of the lateral hypothalamus with the effect of successive lesions in which each unilateral destruction was separated by a 10-day interval. Rats injected with vehicle only (either simultaneously or successively) served as controls. The two types of lesion produced very similar deficits, namely permanent body weight and water intake decreases, as well as a shift to the right in gustatory preference-aversion functions for saccharin (two-bottle procedure). The second aim of the present study was to analyse the effect of morphine (2 mg/kg SC) on saccharin preference in both lesioned and control rats. It was observed that for moderate and high concentrations of the sweetener morphine increased preference for saccharin over water but this effect was similar in both groups of rats. However, with a low concentration of the sweetener (0.3 mM) morphine clearly induced an opposite effect in the two groups of rats: the significant preference for this concentration shown by the control rats after vehicle injection was converted to a neutral response, whereas the neutral response of the lesioned animals after vehicle injection was transformed by morphine to a significant preference for saccharin over water.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Is the bitter rejection response always adaptive?

The bitter rejection response consists of a suite of withdrawal reflexes and negative affective responses. It is generally assumed to have evolved as a way to facilitate avoidance of foods that are poisonous because they usually taste bitter to humans. Using previously published studies, the present paper examines the relationship between bitterness and toxicity in mammals, and then assesses the ecological costs and benefits of the bitter rejection response in carnivorous, omnivorous, and herbivorous (grazing and browsing) mammals. If the bitter rejection response accurately predicts the potential toxicity of foods, then one would expect the threshold for the response to be lower for highly toxic compounds than for nontoxic compounds. The data revealed no such relationship. Bitter taste thresholds varied independently of toxicity thresholds, indicating that the bitter rejection response is just as likely to be elicited by a harmless bitter food as it is by a harmful one. Thus, it is not necessarily in an animal's best interest to have an extremely high or low bitter threshold. Based on this observation, it was hypothesized that the adaptiveness of the bitter rejection response depends upon the relative occurrence of bitter and potentially toxic compounds in an animal's diet. Animals with a relatively high occurrence of bitter and potentially toxic compounds in their diet (e.g., browsing herbivores) were predicted to have evolved a high bitter taste threshold and tolerance to dietary poisons. Such an adaptation would be necessary because a browser cannot "afford" to reject all foods that are bitter and potentially toxic without unduly restricting its dietary options. At the other extreme, animals that rarely encounter bitter and potentially toxic compounds in their diet (e.g., carnivores) were predicted to have evolved a low bitter threshold. Carnivores could "afford" to utilize such a stringent rejection mechanism because foods containing bitter and potentially toxic compounds constitute a small portion of their diet. Since the low bitter threshold would reduce substantially the risk of ingesting anything poisonous, carnivores were also expected to have a relatively low tolerance to dietary poisons. This hypothesis was supported by a comparison involving 30 mammal species, in which a suggestive relationship was found between quinine hydrochloride sensitivity and trophic group, with carnivores > omnivores > grazers > browsers. Further support for the hypothesis was provided by a comparison across browsers and grazers in terms of the production of tannin-binding salivary proteins, which probably represent an adaptation for reducing the bitterness and astringency of tannins.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1996

Supertasting, earaches and head injury: genetics and pathology alter our taste worlds.

Family studies using thresholds showed that PROP (6-n-propylthiouracil) tasting is produced by a dominant allele, T. Nontasters have two recessive alleles and tasters have one or two dominant alleles. The bitterness of suprathreshold PROP and anatomical criteria subdivide tasters into medium and supertasters. Supertasters may be TT tasters, but this has yet to be demonstrated. Supertasters preceive the greatest bitterness and sweetness from many stimuli as well as the greatest oral burn from alcohol and capsaicin. Women are more likely than men to be supertasters. Otitis media and head trauma can alter taste and thus PROP classifications, complicating studies on PROP genetics. Some subjects with a history of otitis media show taste reductions, but others show enhanced tastes and appear to have more taste buds per fungiform papilla. Subjects with head trauma show reduced tastes on some oral loci, but there is evidence that severe reductions on the front of the tongue ameliorate reductions at the circumvallate papillae on the back of the tongue by a release of inhibition mechanism.

Brain Injuries↗
PubMed1991

Children's food preferences and genetic sensitivity to the bitter taste of 6-n-propylthiouracil (PROP).

Genetic sensitivity to bitter taste may be associated with preference or rejection of some foods by children. Thirty-four children aged 5-7 y participated in the following assessments: a threshold test for 6-n-propylthiouracil (PROP), a scaling test to determine PROP sensitivity above threshold concentrations, a taste test of 11 foods and beverages with two methods of assessing preference (order of food selection and hedonic rating), and a verbally administered food-preference questionnaire. The 30 children who completed these tests successfully were classified as nontasters or tasters based on their PROP thresholds as well as their suprathreshold PROP functions. Analysis of variance showed significant differences in acceptance of cheese and milk for the two taste groups on one of the three preference tasks, selection of foods in order of preference. Tasters selected cheese later than did nontasters, suggesting that they like it less. Tasters selected milk earlier than did nontasters, suggesting that they like it more.

Animals↗
PubMed1988

Taste acuity and zinc metabolism in captopril-treated hypertensive male patients.

Hypogeusia is a reported side effect of captopril. Linkage of hypogeusia to zinc deficiency has been suggested. We objectively assessed taste acuity using Henkin's three-drop stimulus technique and measured plasma zinc (PZn) level and urinary zinc excretion in 31 hypertensive patients. Of these, 11 were long-term, high-dose captopril recipients (more than 6 months, 266 +/- 34 mg/day), six were short-term captopril recipients (less than 6 months, 104 +/- 40 mg/daily dose), and the remaining 14 served as noncaptopril controls. Compared to controls, the long-term captopril group had significantly higher taste detection and recognition thresholds, lower PZn (91 +/- 3 vs. 100 +/- 3 micrograms/dl, P less than 0.05) and higher urinary zinc excretion (1017 +/- 89 vs. 609 +/- 76 micrograms/day, P less than 0.005). The short-term captopril group did not differ significantly from the noncaptopril group except for higher taste-recognition thresholds for NaCl and sucrose (P less than 0.05). Discontinuing captopril improved taste acuity and almost normalized zinc parameters in two patients on long-term captopril. These results suggest that abnormalities of taste are commonly associated with captopril therapy and may be related to changes in zinc metabolism. This is especially true in patients on long-term, high-dose captopril therapy.

Captopril↗