Involvement of amino and sulphydryl groups in olfactory transduction in silk moths.
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Amines↗
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Results for “Taste modeling”
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Sensing with TRP channels.
Drosophila melanogaster flies carrying the trp (transient receptor potential) mutation are rapidly blinded by bright light, because of the absence of a Ca2+-permeable ion channel in their photoreceptors. The identification of the trp gene and the search for homologs in yeast, flies, worms, zebrafish and mammals has led to the discovery of a large superfamily of related cation channels, named TRP channels. Activation of TRP channels is highly sensitive to a variety of chemical and physical stimuli, allowing them to function as dedicated biological sensors that are essential in processes such as vision, taste, tactile sensation and hearing.
Animals↗
Antagonistic sensory cues generate gustatory plasticity in Caenorhabditis elegans.
Caenorhabditis elegans shows chemoattraction to 0.1-200 mM NaCl, avoidance of higher NaCl concentrations, and avoidance of otherwise attractive NaCl concentrations after prolonged exposure to NaCl (gustatory plasticity). Previous studies have shown that the ASE and ASH sensory neurons primarily mediate attraction and avoidance of NaCl, respectively. Here we show that balances between at least four sensory cell types, ASE, ASI, ASH, ADF and perhaps ADL, modulate the response to NaCl. Our results suggest that two NaCl-attraction signalling pathways exist, one of which uses Ca(2+)/cGMP signalling. In addition, we provide evidence that attraction to NaCl is antagonised by G-protein signalling in the ASH neurons, which is desensitised by the G-protein-coupled receptor kinase GRK-2. Finally, the response to NaCl is modulated by G-protein signalling in the ASI and ADF neurons, a second G-protein pathway in ASH and cGMP signalling in neurons exposed to the body fluid.
Animals↗
A method for quantifying overall satisfaction of complete denture patients.
Reproducible and quantitative evaluation of patient satisfaction with their complete dentures is of great importance for preoperative diagnosis, treatment planning and assessment of complete denture treatment outcome. This study attempted (1) to clarify the degree of contribution of various factors to overall satisfaction, and (2) to develop a method for quantitative assessment of overall satisfaction with complete dentures. Twelve satisfaction factors and a three-grade scale were used to assess 302 complete denture patients. The contribution of each grade of the 12 factors to the overall satisfaction level was determined by multiple regression analysis. Seven factors were highly correlated to the overall satisfaction. Based on the level of contribution by these seven significant factors, a scoring method for satisfaction was established. Category scores for these factors were calculated and the sum of the category scores was converted to an integer between 0 and 100. The resulting quantification score was closely correlated with overall satisfaction. A protocol for scoring overall satisfaction was developed based on the scientifically analysed contribution of each satisfaction factor.
Aged↗
Prediction of sweetness intensity for equiratio aspartame/sucrose mixtures.
The Equiratio Mixture Model predicts the responses to a series of equiratio mixtures on the basis of the psychophysical functions for the unmixed components. The model predicts the sweetness of mixtures of sugars and sugar-alcohols successfully, but is unable to predict mixture intensity for substances with different dynamic ranges. In this paper, the equi-intensity concept is introduced in the Equiratio Mixture Model by transforming the physical concentrations expressed in molarity into units that produce approximately equi-intense sensations. An empirical test using aspartame/sucrose mixtures shows that the modified Equiratio Mixture Model yields good predictions of mixture intensities.
Adult↗
Specificity of glossopharyngeal nerve responses to astringent compounds in Xenopus.
Astringent compounds were applied to oral epithelium of the clawed toad, Xenopus laevis, and rapidly rising and highly sensitive responses could be recorded from the whole glossopharyngeal nerve, but not at all from the trigeminal nerve. The response to 10 mM tannic acid decreased progressively with repetitive application. These responses to tannic acid, however, recovered completely by treating with chemicals capable of forming strong hydrogen and hydrophobic bonds. These chemical bondings are generally recognized as a model for polyphenol (tannin)-protein interactions based on physico-chemical measurements in vitro. The high affinities of these chemicals for tannic acid may be effective in releasing both bonds in the interaction of tannic acid with the receptor molecules. Our results provide in vivo evidence for this model.
Animals↗
Brazzein, a small, sweet protein: effects of mutations on its structure, dynamics and functional properties.
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Animals↗
Reflex topography in the nucleus of the solitary tract.
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Animal Feed↗
Independent components of the neural population response for discrimination of quality and intensity of chemical stimuli.
The responses of a population of 30 olfactory receptor cells from spiny lobsters to 8 behaviorally relevant complex types of stimuli at 0.005, 0.05 and 0.5 mM were analyzed using multidimensional scaling to evaluate their potential for coding quality and intensity. A discrimination index was derived from the resulting stimulus coordinates, which takes into account the response similarities within type/concentration and the response dissimilarities between types/concentrations. The results indicate that quality and intensity can be discriminated by separate components of the response of the population of neurons: quality by the pattern of responses produced across the neuronal population, and intensity by the absolute response magnitude.
Animals↗
Neuronal and neurochemical substrates of reinforcement.
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Animals↗
[Local and regional complications of a fixed partial denture].
Local and regional complications of the partial dentures are rare and usually benign. Their effects are variable and include: pain, mobility, elocution difficulties, metallic or burnt taste, nausea, esthetic problems or repeated fractures. They are, to a great extent, avoidable if the prosthesis has been well conceived and produced from models studied on a parallelizer, and if occlusion was investigated in all its positions. Their numbers can be reduced by regular surveillance.
Denture Retention↗
[Phylogenetic aspects of the Jacobson's organ and nasopalatine duct topography in insectivores, primates, Tupaia and Didelphis].
A comparative study was made of the anatomy of the skeletal structures of Jacobson's organs and the nasopalatine ducts in insectivores, primates, Tupaia and Didelphis. The adult animals investigated can be devided in 2 groups according to the topography of this region. Each group has its characteristic structures. Tupaia, although a member of the eutherian mammals, shows striking similarities to the marsupial Didelphis. The structure of the nasal region of both points towards an ancestral origin. The organ of Jacobson of those primates and insectivores which were studied, are quite different with respect to the anatomy of these skeletal structures. Closest similarities within these both orders are found in Erinaceus and primates. The other insectivores studied, Talpa and the shrews, differ from them in so far as their cartilages of the corresponding region are for the most part ossificated. It seems that this nasal part is of value in revealing early phylogenetic relations.
Animals↗
Antiaversive properties of opioids in the conditioned taste aversion test in the rat.
The antiaversive effect of mu-, kappa- and delta-opioid receptor agonists against conditioned taste aversion (CTA) induced by apomorphine, lithium chloride and copper sulphate in the rat was studied, in order to evaluate whether prevention of CTA is a suitable model for the study of antiemetics. Anti-aversion was not a general characteristic of all opioid substances tested. Only one dose of the mu-agonist morphine and only one dose of the kappa-agonist ethylketocyclazocine had a consistent antiaversive effect against CTA induced by apomorphine; one dose of the delta-agonist [D-Ala2, Met5]enkephalinamide antagonized the aversion induced by lithium chloride. As the results do not correspond to our previous findings on the antiemetic effects of these opioids in the dog (all mu- and kappa-agonists tested having an antiemetic effect), we conclude that the CTA test cannot be used as a screening test for potentially antiemetic drugs.
Animals↗
Is rat LRRP Ba1-651 a Delta-1-pyrroline-5-carboxylate dehydrogenase activated by changes in the concentration of sweet molecules?
The liver is one of the most complex organs in the body, which responds to hepatocellular damage with inflammatory, regenerative and repair processes designed to restore functional liver tissue mass. Rat LRRP Ba1-651, a liver regeneration related protein induced during partial hepatectomy, is classified as a member of the aldehyde dehydrogenase (ALDh) 4A1 superfamily. During a BLAST protein search, this protein basically showed three structural and functional domains: an intermediate filament-like protein, a Delta-1-pyrroline-5-carboxylate dehydrogenase (P5CDh) and an atrial natriuretic factor (ANF) receptor. We suggest that all amniotic mammals possess a Ba1-651 ortholog to that of rats. The ANF receptor domain of rat LRRP Ba1-651, which domain is part of the receptor family ligand binding region, shows a very high sequence homology (almost identity) to the extracellular amino-terminal domains of the mammalian sweet taste receptor T1R2. This receptor belongs to the type C family of G protein coupled receptors (GPCRs) and is characterized by the presence of large extracellular amino-terminal domains, a nine cysteine domain of family 3 GPCR and a 7tm_3 transmembrane type domain. We suggest that rat LRRP Ba1-651 protein is a liver P5CDh-ANF that is activated by changes in the concentration of sweet molecules. If the sugar concentration in the organ increases due to liver damage or the intake of carbohydrate-rich or protein-rich foods, the P5CDh-ANF enzyme is activated to help in P5C catabolism. The hormone insulin probably plays a key role in the regulation of this enzyme. In the model that we propose, the P5CDh-ANF enzyme is activated by a conformational change in protein structure in the P5C docking site due to sugars binding in the AFN receptor region of the LRRP Ba1-651 protein. Our research could be a further understanding of the biological significance of this P5CDh-ANF enzyme, with important potential applications in the treatment of HPII and liver diseases and in liver transplantation. Further studies of our P5CDh-ANF enzyme are needed to clarify its features and functions, and which substances are involved in its induction. These might use liver cell lines or purified LRRP Ba1-651 protein with sweet molecules in vitro. Other experiments may help to localize LRRP Bal-651 in the organ and to link its abnormal presence or absence to certain tumors like hepatocellular carcinoma.
1-Pyrroline-5-Carboxylate Dehydrogenase↗
Differential involvement of cortical muscarinic and NMDA receptors in short- and long-term taste aversion memory.
In conditioned taste aversion, an animal avoids a taste previously associated with toxic effects, and this aversive memory formation requires an intact insular cortex. In this paper, we investigated the possible differential involvement of cholinergic and glutamatergic receptors in the insular cortex in short-term memory (STM) and long-term memory (LTM) of taste aversion in rats. Taste aversion was induced by intraperitoneal administration of lithium chloride (a malaise-inducing drug) 15 min after experience with an unfamiliar taste. In order to test STM and LTM of taste aversion, taste stimulus was again presented 4 h and 72 h after lithium injection, respectively. During the acquisition, microinjection of the muscarinic antagonist, scopolamine, in the insular cortex before, but not after, the presentation of the new taste, abolished STM as well as LTM. Blockade of the NMDA receptor, in the insular cortex, by AP5 before, but not after, the presentation of the taste stimulus, impaired LTM but left STM intact. Moreover, when injected 1 h after malaise induction (i.e., during taste-illness association), AP5 disrupted both STM and LTM. These results suggest that activation of muscarinic receptors in the insular cortex is involved in the acquisition of taste memory, whereas NMDA receptors participate in taste memory consolidation. These data demonstrate that different neurochemical mechanisms subserve different memory phases. NMDA receptors are also probably involved in processing the visceral input, thus allowing subsequent taste-illness association. This indicates that in the same cortical area the same neurotransmitter system can be involved in distinct processes: taste memory consolidation vs. taste-illness association.
2-Amino-5-phosphonovalerate↗
The effects of phencyclidine on latent inhibition in taste aversion conditioning: differential effects of preexposure and conditioning.
Latent inhibition (LI) is a behavioural procedure in which preexposure to a stimulus not followed by reinforcement retards subsequent conditioning to this stimulus when it is paired with reinforcement. Changes in LI thus reflect greater or lesser retardation of learning which essentially implies a potentiation or an attenuation of the LI effect. LI has proved sensitive to psychotomimetic and antipsychotic treatment, which has encouraged its use to model learning and attention deficits in schizophrenia. In the present study, experiments were conducted to evaluate the effects of the psychotomimetic drug, phencyclidine (PCP, 2 mg/kg), and compare it with D-amphetamine (D-AMP, 0.33 and 1 mg/kg), on LI using a conditioned taste aversion procedure. PCP was found to potentiate LI when administered acutely prior to the conditioning trails, while no such effect was observed when administered prior to the preexposure trials. D-AMP, on the other hand, disrupted LI possibly due to a failure to induce a persistent taste aversion conditioning.
Analysis of Variance↗
Social blockade of taste-aversion learning in Norway rats (Rattus norvegicus): is it a social phenomenon?
In Experiment 1, hooded rats (Rattus norvegicus) were exposed to a novel diet in a food dish or on a conspecific; they were allowed to consume the same diet and then were injected with a toxin LiCl. Later both groups ate more of the novel diet than animals that had not been exposed, and the conspecific-exposed group ate more than the dish-exposed group. Reducing aversion learning by exposure on a conspecific is known as social blockade. We examined if this effect is because a conspecific intensifies dietary cues and thereby increases latent inhibition. Experiment 2 failed to show that diet on a conspecific is a more effective conditioned stimulus for taste-aversion learning than diet in a dish, and Experiment 3 showed that diet in a dish is an effective overshadowing stimulus in aversion learning but diet on a conspecific is not. These results suggest that social blockade cannot readily be assimilated to a latent-inhibition model and may be a distinctly social form of learning.
Animals↗
Bitterness suppression with zinc sulfate and na-cyclamate: a model of combined peripheral and central neural approaches to flavor modification.
PURPOSE: Zinc sulfate is known to inhibit the bitterness of the antimalarial agent quinine [R. S. J. Keast. The effect of zinc on human taste perception. J. Food Sci. 68:1871-1877 (2003)]. In the present work, we investigated whether zinc sulfate would inhibit other bitter-tasting compounds and pharmaceuticals. The utility of zinc as a general bitterness inhibitor is compromised, however, by the fact that it is also a good sweetness inhibitor [R. S. J. Keast, T. Canty, and P. A. S. Breslin. Oral zinc sulfate solutions inhibit sweet taste perception. Chem. Senses 29:513-521 (2004)] and would interfere with the taste of complex formulations. Yet, zinc sulfate does not inhibit the sweetener Na-cyclamate. Thus, we determined whether a mixture of zinc sulfate and Na-cyclamate would be a particularly effective combination for bitterness inhibition (Zn) and masking (cyclamate). METHOD: We used human taste psychophysical procedures with chemical solutions to assess bitterness blocking. RESULTS: Zinc sulfate significantly inhibited the bitterness of quinine-HCl, Tetralone, and denatonium benzoate (DB) (p < 0.05), but had no significant effect on the bitterness of sucrose octa-acetate, pseudoephedrine (PSE), and dextromethorphan. A second experiment examined the influence of zinc sulfate on bittersweet mixtures. The bitter compounds were DB and PSE, and the sweeteners were sucrose (inhibited by 25 mM zinc sulfate) and Na-cyclamate (not inhibited by zinc sulfate). The combination of zinc sulfate and Na-cyclamate most effectively inhibited DB bitterness (86%) (p < 0.0016), whereas the mixture's inhibition of PSE bitterness was not different from that of Na-cyclamate alone. CONCLUSION: A combination of Na-cyclamate and zinc sulfate was most effective at inhibiting bitterness. Thus, the combined use of peripheral oral and central cognitive bitterness reduction strategies should be particularly effective for improving the flavor profile of bitter-tasting foods and pharmaceutical formulations.
Adult↗