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At least 217 records · Page 12Linked to original sources
PubMed1989

Characteristic response to taste stimuli of the intensities of higher harmonics in an electrochemical oscillatory system.

In general, the electrochemical characteristics of solid/liquid or liquid/liquid interfaces are highly nonlinear, i.e., the capacitance changes markedly according to the applied voltage. In this paper, we propose a novel method for evaluating these nonlinear characteristics quantitatively. That is, a sinusoidal voltage source is applied to a test solution and the waveform of the output current is analyzed by Fourier transformation. It is shown theoretically that higher harmonic components in the Fourier transformation afford us useful information on nonlinear behavior. It is stressed that our technique is entirely different from the classical impedance method, i.e., nonlinear components of the impedance can be evaluated in our method, having been ignored previously in the classical impedance measurement. As an application of this method, we have studied the effect of taste compounds on the intensities of the higher harmonics, using an electrochemical cell containing an aqueous solution of sodium oleate. It has been found that the intensities of the higher harmonics exhibit characteristic changes upon the addition of taste compounds, the change being dependent upon the taste category. The characteristic response to taste compounds in the electrochemical nonlinearity is discussed in relation to the experimental trend of the dynamic isotherm for oleic acid at an air/water interface.

Animals↗
PubMed1995

Transganglionic degeneration in the gustatory system consequent to chorda tympani damage.

The chorda tympani taste nerve is prone to damage in humans. Chorda tympani damage results in taste loss accompanied by altered taste sensations, e.g., phantom tastes. To understand taste alterations this study explores the central and peripheral anatomical consequences of taste nerve injury in an animal model. The chorda tympani was severed in the middle ear of hamsters and the animals were allowed to survive for 2-161 days when sections of the brain were stained for degenerating axons with the Fink-Heimer method. Degenerating axons were present in the chorda tympani termination zone in the nucleus of the solitary tract of every case. Thus, peripheral nerve damage in the taste system results in degeneration of central axonal endings as in other sensory systems (e.g., trigeminal, vestibular). To evaluate whether the central degeneration results from ganglion cell death, geniculate ganglion cells were labeled with Fast blue by tongue injections before neurotomy, and the cells were counted 13-48 days after neurotomy. Numbers of labeled cells from experimental ganglia did not differ significantly from those in control ganglia. Moreover, the experimental cells could be double-labeled by tongue injections with a second marker, diamidino yellow or nuclear yellow, after 40 days postneurotomy. We conclude that degeneration of central axons after taste nerve section represents a long-lasting transganglionic process that likely disrupts the synaptology of the central taste system. The altered synaptology could relate to taste phenomena of central origin reported for nerve-injured patients. Geniculate ganglion cells generally survive neurotomy and can regenerate axons to the tongue.

Animals↗
PubMed2003

Family history of alcoholism and response to sweets.

BACKGROUND: The relationship between a hedonic response to sweet tastes and a propensity to excessive alcohol drinking is supported by both animal and human studies. This study was designed to test the hypothesis that the genetic risk for alcoholism as measured by a paternal history of alcoholism in young social drinkers is associated with sweet-liking, defined as rating the strongest offered sucrose solution (i.e., 0.83 M) as the most palatable during the standard sweet test. METHODS: Participants were 163 subjects (39% male) without a lifetime history of alcohol or drug abuse or dependence. Eighty-one subjects had a paternal history of alcoholism (FH+), and 82 did not (FH-). Each subject rated a series of sucrose solutions for intensity of sweetness and palatability. Subjects were categorized as sweet-likers if they rated the highest sucrose concentration as the most pleasurable. RESULTS: The estimated odds of being a sweet-liker were 2.5 times higher for FH+ than for FH- subjects. FH+ subjects disliked the tastes of the two weakest offered sucrose concentrations (0.05 and 0.10 M), whereas FH- subjects reported these tastes to be neutral. CONCLUSIONS: The results of this study support the hypothesis that sweet-liking is associated with a genetic vulnerability to alcoholism.

Adult↗
PubMed2026

Genome-Wide Association Analyses of Bitter Food Preferences Link Genetic Loci to Sensory and Metabolic Pathways.

BACKGROUND: Genetic variation is implicated in individual preferences for bitter-tasting foods. However, previous studies have focused on candidate genes and limited varieties of bitter-tasting foods and have treated food preference scale responses as continuous data. OBJECTIVES: The present investigation aimed to identify genetic variants associated with preferences for bitter-tasting foods using ordinal multinomial regression models in genome-wide association studies (GWAS). In addition, post-GWAS functional annotation and mapping, genetic correlations, and associations with dietary intake were examined. METHODS: Food preference and genome-wide genotyping data were used from the UK Biobank (n = 125,578). Preference data from Likert scale rankings (from 1 to 9) for 12 individual foods were analyzed using ordinal multinomial regression GWAS. In addition, 1 composite continuous variable was created for preference for cruciferous vegetables as a group and analyzed using a linear mixed-model GWAS to enable the calculation of a polygenic score (PGS) for cruciferous vegetable preference. Convergent validity of GWAS results was assessed with dietary intake data for the same food items in the CARTaGENE cohort (n = 8176). Post-GWAS gene-level and pathway-level association analyses were conducted in MAGMA (Multimarker Analysis of GenoMic Annotation). RESULTS: Forty-six single-nucleotide polymorphisms (SNPs) were identified for preferences for 11 bitter-tasting foods at a genome-wide significance level (P < 7.14 &#xd7; 10-9). Gene-set analysis for enrichment identified pathways related to caffeine metabolism and bitter taste perception for preference of coffee without sugar and grapefruit, respectively. Genes with higher expression in brain tissues showed stronger genetic associations with cruciferous vegetable preference. The PGS for cruciferous vegetable preference was weakly correlated with intake (r = 0.05, P < 0.0001), but individual SNPs were not associated with intake in a consistent manner. CONCLUSIONS: Genetic variation contributes to preferences for bitter-tasting foods among adults, and some links with food intake are detectable. Nevertheless, effect sizes are small and inconsistent, reflecting the multifactorial complexity of food intake.

bitter taste↗
PubMed2000

Cyclodextrin encapsulation to prevent the loss of l-menthol and its retention during drying.

The taste and flavor of spray-dried powdered products are the most important quality factors. In the present study, molecular encapsulation in cyclodextrin was applied to prevent the loss of a hydrophobic flavor compound (l-menthol) during the drying of a droplet. beta-Cyclodextrin appeared to be a better encapsulant for menthol than alpha- and gamma-cyclodextrin. The retention of menthol increased with increasing concentration of both cyclodextrin and maltodextrin. A simple mathematical model is proposed for estimating the flavor retention. The theoretical results by this model estimated well the final retention of menthol encapsulated in a blend of beta-cyclodextrin and maltodextrin.

Cyclodextrins↗
PubMed1989

Examination of specific nutrition/health behaviors using a social cognitive model.

Nutrition intervention programs are not always successful. In some cases, an insufficient understanding of the interrelationships among factors influencing health behaviors may be responsible for the failures. This study used social cognitive theory, a framework for studying behaviors, to structure the relationships between measurable factors important to the frequency of health-oriented food consumption. We developed a model that incorporated factors for social environment, reinforcement, commitment, behavior modeling, knowledge, and attitude relative to the frequency of consumption of four beverages (whole milk, low-fat/skin milk, regular soda, and diet soda). Four-hundred fifty-seven middle-aged adults (mean age, 47 years; 58% female) and 709 college students (mean age, 21 years; 50% female) responded to a written questionnaire designed as a self-report on frequency of consumption and measures for 10 social cognitive variables. For all four beverages, the model explained 35% or more of the variance in frequency of consumption, thus confirming its predictive power. We used the statistical approach known as path analysis to examine the relationships within the model. The analysis demonstrated that factors influencing the consumption varied between the two age groups (e.g., nutrition knowledge was related to attitude in adult soda-drinking models but not in student soda-drinking models) and between forms of the beverages (e.g., for student models, nutrition knowledge was related to taste enjoyment for low-fat/skim milk but not for whole milk).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

Aversive sensation in the brain after eating unpalatable food.

Taste plays an important role in the regulation of food and fluid intake in animals. Taste information on the tongue is transmitted to the brain, and we feel hedonic or aversive sensation from the taste of a food. Various studies have shown that opioids or the dopamigenic system is deeply related to the hedonic response in the brain. Few studies have been made, however, about the aversion to food, which is an important signal for animals to protect them from poison that usually has a bitter taste and causes an aversive sensation. We recently suggested that diazepam binding inhibitor (DBI) was released in the brain after stimulation by an aversive taste and might be involved in the aversive sensations of taste. In this review we describe the studies on aversive sensation after eating and propose a novel concept that food aversion may be divided into aversion and rejection. Furthermore, we suggest that DBI is involved in aversion.

Animals↗
PubMed2004

Taste perception: how to make a gourmet mouse.

Sugars and amino acids are mainly associated with desirable taste sensation. A new study using knockout mouse models shows that the detection of various sugars, artificial sweeteners and L-amino acids is exclusively mediated by taste cells that express one or pair-wise combinations of three G protein coupled receptors, T1R1, T1R2 and T1R3

Afferent Pathways↗
PubMed1998

Neurotrophic factors in the tongue: expression patterns, biological activity, relation to innervation and studies of neurotrophin knockout mice.

How taste buds develop and how they become innervated has been a matter of debate for a long time. Brain-derived neurotropic factor (BDNF) and neurotrophin-3 (NT3) mRNA expression patterns suggested a possible involvement in lingual gustatory and somatosensory innervation. Studies of null-mutated mice showed that BDNF-/- mice had few abnormal taste buds and were unable to discriminate between primary tastes. NT3-/- mice had a severe loss of lingual somatosensory innervation. These novel findings may have clinical implications in rare human conditions such as familial dysautonomia and/or in more common cases of problems with loss of taste and sensation in the mouth such as those seen after injury to the nerves, either by accident or following oral/facial surgery. Knowledge about which proteins that are required to stimulate nerve fibers to grow into mucous membranes of the oral cavity during development suggests that these same proteins might become helpful in stimulating regeneration of injured nerves in patients, perhaps helping them to regain lost taste and sensory functions. Here, the presence of glial cell-derived neurotrophic factor (GDNF) families of neurotrophic factors and receptors in the tongue is also discussed. Further, a model for the development and innervation of taste buds in mammals is proposed.

Animals↗
PubMed2001

Seeing mum drinking a 'light' product: is social learning a stronger determinant of taste preference acquisition than caloric conditioning?

OBJECTIVE: It was examined whether caloric conditioning or social learning strategies dominate in taste preference acquisition in children. The caloric learning paradigm predicts that eating or drinking artificially sweetened products, which deliver virtually no energy, will not lead to a taste preference whereas the social learning paradigm predicts that seeing important others modelling the eating and drinking of these 'light' products will induce a preference for the taste of light products in the child. DESIGN: In a 2 x 2 between subjects factorial design, the amount of energy and social modelling was varied. SETTING: The study was undertaken at primary schools in Maastricht, The Netherlands. SUBJECTS: Forty-five children participated and six children dropped out. The 39 children who completed the study (14 boys and 25 girls) had a mean age of 67 months (range 51--81, s.d. 5.6). INTERVENTIONS: Each subject took part in nine conditioning trials with an individually selected tasting yoghurt which was not preferred very much at the pre-test. RESULTS: The children in the combined caloric and social condition showed an increase in their preference for the conditioned taste which was larger than a regression-to-the-mean effect (P=0.007), whereas children in the other groups did not. CONCLUSION: Caloric and social learning combined, ie modelling the consumption of energy-rich foods or drinks, is the best way to establish taste preferences. Children more easily learn a preference for energy-rich food that is eaten by significant others than for food that is low in energy and eaten by significant others.

Child↗
PubMed2002

Why are sweet proteins sweet? Interaction of brazzein, monellin and thaumatin with the T1R2-T1R3 receptor.

Sweet tasting proteins interact with the same receptor that binds small molecular weight sweeteners, the T1R2-T1R3 G-protein coupled receptor, but the key groups on the protein surface responsible for the biological activity have not yet been identified. I propose that sweet proteins, contrary to small ligands, do not bind to the 'glutamate-like' pocket but stabilize the free form II of the T1R2-T1R3 receptor by attachment to a secondary binding site. Docking of brazzein, monellin and thaumatin with a model of the T1R2-T1R3 sweet taste receptor shows that the most likely complexes can indeed stabilize the active form of the receptor.

Arabidopsis Proteins↗
PubMed1996

Mechanism of nonlinear responses of taste cells to mixed tastes.

Coupling between ionic flows through different kinds of channels affects essentially the responses of multisensitive taste cells to single- and mixed-taste stimuli. The mechanism of taste transduction is studied by using a realistic model of the multisensitive cells of the rat. The transduction pathways considered are amiloride-sensitive Na+ channels for NaCl and HCl and adenosine 3',5'-cyclic monophosphate-mediating K+ channels for sucrose. Contributions of paracellular pathways and taste-insensitive ionic channels are also studied. The calculated responses of various multisensitive cells induced by single stimuli of NaCl, HCl, or sucrose reproduce experimentally observed responses as well. The two main conclusions are as follows. 1) Whether the response of a cell to a binary mixture becomes synergetic or antagonistic can be estimated from the individual responses of the cell to each component of the mixture. 2) Whether the response is enhanced or suppressed by addition of a new taste to the original taste can be determined, for most receptive cells, from a viewpoint of linear superposition of the individual responses.

Animals↗
PubMed2001

Calcium: taste, intake, and appetite.

This review summarizes research on sensory and behavioral aspects of calcium homeostasis. These are fragmented fields, with essentially independent lines of research involving gustatory electrophysiology in amphibians, ethological studies in wild birds, nutritional studies in poultry, and experimental behavioral studies focused primarily on characterizing the specificity of the appetite in rats. Recently, investigators have begun to examine potential physiological mechanisms underlying calcium intake and appetite. These include changes in the taste perception of calcium, signals related to blood calcium concentrations, and actions of the primary hormones of calcium homeostasis: parathyroid hormone, calcitonin, and 1,25-dihydroxyvitamin D. Other influences on calcium intake include reproductive and adrenal hormones and learning. The possibility that a calcium appetite exists in humans is discussed. The broad range of observations documenting the existence of a behavioral limb of calcium homeostasis provides a strong foundation for future genetic and physiological analyses of this behavior.

Animals↗
PubMed1993

What's so special about special visceral?

The brainstem is classically divided into functional columns including special and general subdivisions for somatic and visceral components. The term 'special visceral motor' is applied to branchiomotor nuclei, while 'special visceral sensory' refers to nuclei devoted to incoming gustatory and olfactory senses. The use of the term 'special visceral motor' is questioned in that the branchiomotor neurons function more like general somatic than general visceral motoneurons. The designation of taste and smell as 'special visceral sensory' systems seems inconsistent on several bases. First, taste and smell are not homologous systems: (1) the receptors are grossly dissimilar in morphology and relationship to other elements of the nervous system; (2) the two systems mediate very different behaviors and respond to different types of chemical stimuli, and (3) chemosensory systems are not 'special' (i.e. limited to cranial nerves) in that solitary chemoreceptor cells, which are distributed across the body surface, can be innervated by spinal or cranial nerves. Finally, taste is considered 'special' because it involves specialized chemosensory end organs; the visceral nerves also provide innervation to other specialized chemoreceptors (e.g. carotid body) which are considered part of the general visceral sensory system. Thus the term 'special visceral sensory' appears without solid foundation when applied to gustatory systems in contradistinction to nongustatory branchial and thoracic interoceptive systems. A reformulation of the functional columns of the brainstem is suggested in which six columns can be identified: (1) somatic motor; (2) branchial motor; (3) visceral motor; (4) visceral sensory; (5) somatic sensory, and (6) hair cell (dorsolateral placode) sensory.

Animals↗
PubMed2006

Crystal structure of neoculin: insights into its sweetness and taste-modifying activity.

Although the majority of sweet compounds are of low molecular mass, several proteins are known to elicit sweet taste responses in humans. The fruit of Curculigo latifolia contains a heterodimeric protein, neoculin, which has both sweetness and a taste-modifying activity that converts sourness to sweetness. Here, we report the crystal structure of neoculin at 2.76A resolution. This is the first well-defined tertiary structure of a taste-modifying protein of this kind. The overall structure is quite similar to those of monocot mannose-binding lectins. However, crucial topological differences are observed in the C-terminal regions of both subunits. In both subunits of neoculin, the C-terminal tails turn up to form loops fixed by inter-subunit disulfide bonds that are not observed in the lectins. Indeed, the corresponding regions of the lectins stretch straight over the surface of another subunit. Such a C-terminal structural feature as is observed in neoculin results in a decrease in subunit-subunit interactions. Moreover, distribution of electrostatic potential on the surface of neoculin is unique and significantly different from those of the lectins, particularly in the basic subunit (NBS). We have found that there is a large cluster composed of six basic residues on the surface of NBS, and speculate that it might be involved in the elicitation of sweetness and/or taste-modifying activity of neoculin. Molecular dynamics simulation based on the crystallography results suggests that neoculin may adopt a widely "open" conformation at acidic pH, while unprotonated neoculin at neutral pH is in a "closed" conformation. Based on these simulations and the generation of a docking model between neoculin and the sweet-taste receptor, T1R2-T1R3, we propose the hypothesis that neoculin is in dynamic equilibrium between open and closed states, and that the addition of an acid shifts the equilibrium to the open state, allowing ligand-receptor interaction.

Amino Acid Sequence↗
PubMed2006

Natural sweet macromolecules: how sweet proteins work.

A few proteins, discovered mainly in tropical fruits, have a distinct sweet taste. These proteins have played an important role towards a molecular understanding of the mechanisms of taste. Owing to the huge difference in size, between most sweeteners and sweet proteins, it was believed that they must interact with a different receptor from that of small molecular weight sweeteners. Recent modelling studies have shown that the single sweet taste receptor has multiple active sites and that the mechanism of interaction of sweet proteins is intrinsically different from that of small sweeteners. Small molecular weight sweeteners occupy small receptor cavities inside two subdomains of the receptor, whereas sweet proteins can interact with the sweet receptor according to a mechanism called the 'wedge model' in which they bind to a large external cavity. This review describes these mechanisms and outlines a history of sweet proteins.

Amino Acid Sequence↗