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Fenfluramine-induced modification of palatability: analysis by the taste reactivity test.

The ability of various doses (0, 1.25, 2.5, and 5.0 mg/kg) of fenfluramine to modify the palatability of sucrose and quinine solutions was assessed by means of the taste reactivity test. Although fenfluramine did not modify the positive hedonic ingestive reactions elicited by sucrose solution, it consistently enhanced the negatively hedonic aversive reactions elicited by unpalatable 0.05% quinine solution and moderately palatable 2% sucrose solution. The results suggest that fenfluramine enhances the aversive properties of tastants without suppressing the positive hedonic properties of tastants. The results support a two-dimensional model of palatability.

Animals↗

Adaptation to capsaicin within and across days.

Subjects judged the time-course of the burn caused by 100 ppm capsaicin applied to the tongue on Day 1 and Day 5. On Days 2-4, they tasted hard candy containing capsaicin. Most subjects did not show adaptation within Day 1, but either plateaued after about 16 min or rose monotonically for the entire 34 min. Intensity was less on Day 5 and levelled off or declined for most subjects. Data were fit to a mathematical model of adaptation. Adaptation across days was accounted for by changes in the gains of the three processes.

Adaptation, Physiological↗

Averaging expectancies and perceptual experiences in the assessment of quality.

This study examines whether people integrate expectancy information with perceptual experiences when evaluating the quality of consumer products. In particular, we investigate the following three questions: (1) Are expectancy effects observed in the evaluation of consumer products? (2) Can these effects be viewed in cognitive processing terms? (3) Can a mathematical model based on the averaging of attribute information describe the effects? Participants in two experiments blindly evaluated (with the product names removed) consumer products from six sensory modalities: vision (computer printer output), tactile (paper towels), olfaction (men's cologne), taste (corn chips), auditory (audio cassette tapes), and tactile/medicinal (hand lotion). Participants in both experiments were asked to: (1) rate the overall quality of the product given arbitrary quality labels (High Quality, Medium Quality, or Low Quality); (2) rate the overall quality of the product without the labels, and (3) estimate the scale values for the quality labels alone. Group results revealed main effects of the quality labels in all product categories. The pattern of results could be described by an averaging model based on Information Integration Theory. These results have implications for placebo effects in consumer behavior and decision making.

Attitude↗

Preferences for tastes paired with a nicotine antagonist in rats chronically treated with nicotine.

The present report addressed the hypothesis that withdrawal from chronic nicotine treatment activates the same motivational processes as withdrawal from chronic opiate treatment. Conditioning produced by the nicotine antagonist mecamylamine in nicotine-treated animals was studied and compared to the well-known potentiation by opiate treatment of the aversive conditioning produced by the opiate antagonist naloxone. A sensitive two-flavor, three-trial, taste conditioning procedure was used and it was found that chronic treatment using Alzet minipumps for 1 month with nicotine (8 or 16 mg/kg/day) potentiated the ability of mecamylamine to produce taste conditioning. Thus, in nicotine-placebo control animals, only 1.0 mg/kg mecamylamine (s.c.) produced significant conditioning, whereas in nicotine-treated animals 0.5 and 1.0 mg/kg mecamylamine was effective. However, in contrast to chronic opiate treatment, which increases the aversive effect of an opiate antagonist (as confirmed here using treatment for one month with 0.25 mg/kg/day fentanyl and taste conditioning with 0.1 mg/kg naloxone, s.c.), the nicotine treatment changed the valence of the mecamylamine conditioning. The nicotine-naive animals avoided the mecamylamine-paired flavor, whereas the nicotine-exposed subjects preferred it. These findings indicated that there may be important differences between nicotine and opiate withdrawal. Not all effects of nicotine withdrawal in models of addiction can be assumed to be negatively motivating.

Animals↗

PYY(3-36) reduces food intake and body weight and improves insulin sensitivity in rodent models of diet-induced obesity.

The gut hormone peptide YY (PYY) was recently proposed to comprise an endogenous satiety factor. We have studied acute anorectic functions of PYY(3-36) in mice and rats, as well as metabolic effects of chronic PYY(3-36) administration to diet-induced obese (DIO) mice and rats. A single intraperitoneal injection of PYY(3-36) inhibited food intake in mice, but not in rats. We next investigated the effects of increasing doses (100, 300, and 1,000 microg.kg-1.day-1) of PYY(3-36) administered subcutaneously via osmotic minipumps on food intake and body weight in DIO C57BL/6J mice. Whereas only the highest dose (1,000 microg.kg-1.day-1) of PYY(3-36) significantly reduced food intake over the first 3 days, body weight gain was dose dependently reduced, and on day 28 the group treated with 1,000 microg.kg-1.day-1 PYY(3-36) weighed approximately 10% less than the vehicle-treated group. Mesenteric, epididymal, retroperitoneal, and inguinal fat pad weight was dose dependently reduced. Subcutaneous administration of PYY(3-36) (250 and 1,000 microg.kg-1.day-1) for 28 days reduced body weight and improved glycemic control in glucose-intolerant DIO rats. Neither 250 nor 1,000 microg/kg PYY(3-36) elicited a conditioned taste aversion in male rats.

Animals↗

Age-related changes in sensory and secretomotor nerve endings in the larynx of F344/N rat.

The aim of the present study was to define the age-related changes in sensory and secretomotor nerve endings in the larynx of F344/N rats. For this purpose, laryngeal tissue sections obtained from 12-, 24- and 35-month-old F344/N rats were compared with respect to the density, distribution and morphology of various types of sensory and secretomotor nerve endings immunoreactive for protein gene product 9.5 (PGP 9.5), calcitonin gene-related peptide (CGRP) and substance P (SP). Two distinct forms of PGP 9.5-immunoreactive motor end-plates were noted; the large sized motor end-plates localized in thyroarytenoid and cricoarytenoid muscles were degenerated in aged rats, while the small sized motor end-plates, localized predominantly in vocal muscles, did not show any age-related changes. CGRP- and SP-immunoreactive nerve fibres of the laryngeal glands did not show any age-related changes. Subepithelial laminar nerve endings immunoreactive to PGP 9.5 showed degeneration with ageing. Aggregates of terminal arborisations in the subepithelial region were smaller in aged animals. PGP 9.5-immunostained taste cells and well-developed subgemmal network were abundant in 12- and 24-month-old rats, but only a few were noted in aged rats. The total number of taste buds decreased significantly with ageing. CGRP- and SP-immunostained taste bud-nerve endings were noted in 12- and 24-month-old rats, but only rarely in 35-month-old rats. The laryngeal epithelium contained PGP 9.5-, CGRP- and SP-immunoreactive thin free nerve endings with many varicosities; their number and distribution were similar between 12- and 24-month-old rats, while only a few endings were observed in 35-month-old rats. Our results indicated that ageing is associated with the reduction of laryngeal sensory and secretomotor nerve endings.

Aging↗

The mechanism of interaction of sweet proteins with the T1R2-T1R3 receptor: evidence from the solution structure of G16A-MNEI.

The mechanism by which sweet proteins elicit a response on the T1R2-T1R3 sweet taste receptor is still mostly unknown but has been so far related to the presence of "sweet fingers" on the protein surface able to interact with the same mechanism as that of low molecular mass sweeteners. In the search for the identification of sweet fingers, we have solved the solution structure of G16A MNEI, a structural mutant that shows a reduction of one order of magnitude in sweetness with respect to its parent protein, MNEI, a single-chain monellin. Comparison of the structures of wild-type monellin and its G16A mutant shows that the mutation does not affect the structure of potential glucophores but produces a distortion of the surface owing to the partial relative displacement of elements of secondary structure. These results show conclusively that sweet proteins do not possess a sweet finger and strongly support the hypothesis that the mechanism of interaction of sweet-tasting proteins with the recently identified T1R2-T1R3 GPC receptor is different from that of low molecular mass sweeteners.

Binding Sites↗

The behavior of APO-SUS rats in animal models with construct validity for schizophrenia.

Schizophrenic patients are known to suffer from a number of information processing disturbances, including deficits in both prepulse inhibition of startle and latent inhibition. Since these behavioral phenomena can also be observed in animals, they represent an ideal starting point for developing animal models having construct validity for specific deficits observed in schizophrenia. The principal question is how to induce a condition in animals most similar to the schizophrenic deficit. In the present study, we have selected rats on the basis of their response to an open filed or to the dopaminergic agonist apomorphine, and evaluated their prepulse inhibition and latent inhibition. We used three different selection procedures (open field selection for novelty response, gnawing cage selection for apomorphine response, and pharmacogenetic selection for apomorphine response). The results show that, irrespective of the selection procedure used, rats with a high response to novelty or apomorphine susceptible (collectively called APO-SUS rats) show diminished prepulse inhibition of the acoustic startle response as compared to rats with a low response to novelty or apomorphine unsusceptible (collectively called APO-UNSUS rats). This difference was apparent only at low prepulse intensities. Moreover, these APO-SUS rats show diminished latent inhibition in a conditioned taste aversion paradigm as compared to APO-UNSUS rats. Given the fact that the pharmacogenetically bred APO-SUS rats show several central nervous, endocrinological, and immunological similarities to schizophrenic patients, they are hypothesised to represent an interesting nonpharmacological animal model for schizophrenia-prone patients.

Animals↗

Neuropeptides and appetite: contribution of neuropharmacological modeling.

It is now clear that a variety of neuropeptides interact with the more classically defined neurotransmitters to stimulate or inhibit feeding. An extensive peripheral peptide satiety system has been identified. Peptides involved in this system include cholecystokinin, bombesin, gastrin-releasing peptide, glucagon, somatostatin, and possibly thyrotropin-releasing hormone and calcitonin. Some of these peptides appear to inhibit feeding by activating ascending fibers in the vagus, whereas others exert their actions independent of the vagus. In addition, neuropeptides appear to play a role in producing the neuromodulatory effects of taste on appetite, and hormones from the endocrine system modulate neuropeptide effects on feeding. The central appetite regulatory system appears to be arranged in a cascade, with an interaction between dynorphin and dopamine producing a part of the feeding drive. This drive is held in check by a variety of neuropeptides including calcitonin, corticotropin-releasing factor, and bombesin. In turn, these peptides are modulated by a norepinephrine-alpha-aminobutyric acid (GABA) system. Neurotensin, serotonin, cyclohistidyl proline diketopiperazine, and the peripheral satiety system appear to modulate the norepinephrine-GABA disinhibitory system. By the judicious use of neuropharmacological modeling we have developed a model of the neurotransmitter interactions involved in appetite regulation that can act as a springboard for the design of future experiments to unravel the mysteries of appetite regulation.

Animals↗

Peptides from milk proteins and their properties.

This review has attempted to study the literature pertaining to peptides derived from milk proteins. Hydrolysis of milk proteins to generate peptides has been practiced for a long time and it was recognized early on in this process that the taste of hydrolyzates might hinder use of these products in food formulations. Modification of protein is necessary to form a more acceptable or utilizable product, to form a product that is less susceptible to deteriorative reactions and to form a product that is of higher nutritionall quality. Modifications may be achieved by a number of chemical and enzymatic means. This review has considered only enzymatic modification of dairy proteins. Modified proteins contain peptides and some of these peptides have been purified and their functionalities have been compared with unmodified proteins. This paper has examined the literature pertaining to improvement in functionality of enzyme-modified proteins. Improvements in solubility, emulsification, foaming and gelation were examined. There is limited information available on the sequence of the peptides necessary to improve the functional characteristics of proteins. Knowing the sequences of desirable functional peptides can lead to genetic alteration of proteins to improve functionality. Addition of synthetic peptides to intact proteins may be another way in which the functionality of proteins can be augmented. Some of the peptides in milk proteins are capable of affecting biological functions of an organism. These effects can be antimicrobial and probiotic, i.e., prevent the growth and proliferation of undesirable and pathogenic organisms, or they may promote the growth of desirable bacteria in the digestive tract of humans and animals. Peptides derived from milk protein have been shown to exert digestive and metabolic effects as well. They may also influence the immune system. These biological effects may play an important role in the development of medical foods that treat or mitigate the effects of diseases. Proteins are allergens and therefore it is possible that products derived from modification of proteins may also be allergens. The known literature about the allergenicity of peptides derived from milk proteins has been examined in this article. Last, but not the least, the taste attributes of peptides is also considered. Bitterness of hydrolyzates is a common occurrence and the origins of these bitter peptides and possible ways of mitigating this sensory defect has been discussed. Many of the peptides that enhance functionality and exert biological activity are likely to be bitter. Therefore, the bitter taste of hydrolysis products has to be dealt with in boosting the functional or nutraceutical aspects of foods containing these peptides. Analytical techniques for sequencing peptides have become more accessible and purification of peptides is commercially feasible. Computer based modeling techniques have aided the prediction of structures in these peptides. These advances, coupled with the advances in biotechnology, promise to revolutionize the future of nutraceutical and functional foods.

Animals↗

Meat consumption and commitments on meat policy: combining individual and public health.

Although meat consumption plays a significant role for individual and public health, there is only little empirical research on the motives of meat consumption informed by health psychology and hardly any on socio-political commitments concerning general meat production taking on a public health perspective. To fill this gap, a questionnaire study was conducted to examine the links between both disciplines. Correlational and multiple regression analyses reveal that individual meat consumption is primarily based on self-centred judgments of control beliefs protecting ones health and of taste, whereas socio-political commitments are based on a mixture of self-centred judgments and animal ethics. Based on these results, it is concluded, that models on health behaviour should integrate the social perspective, and that in intervention programs issues of individual as well as public health should be given equal importance.

Adult↗

Effects of priming positive and negative outcomes on drinking responses.

The purpose of this investigation was to study the effects of priming positive and negative expectancy outcomes on the drinking responses of college students. Men and women (N = 64) were randomly assigned to 1 of 3 priming conditions: a positive expectancy outcome condition, a negative expectancy outcome condition, and a neutral (control) condition. Participants were exposed to a series of semantic primes corresponding to their condition and then asked to complete a beer taste-rating task. Planned comparisons revealed that the average ratio of beer consumed to body weight in the positive condition was significantly greater than the average ratio in the neutral condition, and the average ratio of beer consumed to body weight was significantly less in the negative condition than the average ratio in the neutral condition. These findings are discussed as they relate to cognitive models of alcohol use.

Adolescent↗

Discriminating memories for actual and imagined taste experiences: a reality monitoring approach.

Blindfolded subjects tasted 4 common fruits and imagined the taste of 4 others while focusing on either a few (low sensory detail [SD] or many (high SD) of the fruit's sensory qualities. One week later, subjects judged whether each of 12 fruit names represented a fruit that was previously tasted, imagined tasted, or new (reality monitoring). The major finding was a significant interaction between source (imagined, perceived) and SD level (low, high). Source monitoring was accurate for imagined and perceived fruits in the low SD condition and for perceived fruits in the high SD condition. As predicted, subjects tended to misattribute memories for imagined fruits to perception in the high SD condition. The findings are discussed with reference to the Johnson-Raye reality monitoring model and recent work on memory source confusions.

Adult↗

Relating ionisation of calcium chloride in saliva to bitterness perception.

Saliva plays a role in the perception of bitter, sour and salty tastes that are presumed to be derived from the concentration of free cations or anions ions dissolved in saliva. The role of ionisation of calcium in bitter taste was studied by determining binding in vitro mixture of saliva and protein solutions and in spit. In vitro, the addition of whey to calcium chloride solutions increased the calcium binding, pH and viscosity. The addition of saliva to these mixtures, the increased calcium binding and the induced small changes in viscosity and pH were thought not to contribute significantly to bitterness perception. Nonstimulated saliva, at pH 7.5, contained about 5 mM calcium, of which about one third was ionised. The bitter threshold of fully ionised calcium chloride in water varied between 1 and 15 mM among individuals. In spit, after tasting whey, ionised calcium was found to have increased at low, but decreased at high, calcium concentrations and varied 30% among individuals. Bitterness was related, on average, to the concentration of ionised calcium and not to the total concentration of calcium in spit. A general explicative model based on the composition of bulk saliva is discussed in relation to perception threshold and the likely importance of saliva from von Ebner's gland.

Adult↗

Comfort and Usability of Digital Versus Conventional Custom-Fit Mouthguards: A Randomized Clinical Trial.

BACKGROUND/OBJECTIVES: The use of mouthguards protects teeth and the supporting tissues against impacts. Digital impressions and 3D-printed models can reduce manufacturing steps and minimize discomfort. This study evaluated the fit, comfort, and usability of custom-made mouthguards, obtained by conventional and digital workflow, in amateur athletes. MATERIALS AND METHODS: Amateur athletes were recruited for this randomized, double-blind, crossover clinical study. Each participant received two 4-mm-thick custom-fit mouthguards made of ethylene vinyl acetate (EVA) sheets using two protocols: conventional impression using alginate to produce dental stone cast (CMP) and intraoral digital scanning to produce 3D-printed resin models (DMP). Each mouthguard was worn during all training and matches over 3&#x2009;months. The order of mouthguard use was randomly assigned. Patient satisfaction with the impression protocol and mouthguard use, model accuracy, and mouthguard fit were assessed. RESULTS: Overall, 46 participants completed the study. The DMP protocol required less execution time (p&#x2009;=&#x2009;0.023), caused less discomfort (p&#x2009;=&#x2009;0.018), anxiety (p&#x2009;=&#x2009;0.008), nausea (p&#x2009;=&#x2009;0.027), difficulty breathing (p&#x2009;<&#x2009;0.001), and unpleasant taste (p&#x2009;=&#x2009;0.006) compared to the CMP protocol. The pain (p&#x2009;=&#x2009;0.971) perceived by the participants was similar in both impression protocols. The CMP-mouthguards were considered to be better fitting by the majority of participants (p&#x2009;=&#x2009;0.027). Between-group comparisons revealed that DMP-mouthguard caused less discomfort immediately postadaptation (p&#x2009;=&#x2009;0.034), with no significant differences observed at 30 or 90&#x2009;days. CONCLUSIONS: The digital workflow demonstrated to be efficient in the fabrication of mouthguards. Digital impression was more comfortable, requiring less execution time, with more accurate printed models and produced mouthguards with reported comfort and fit levels similar to those manufactured conventionally.

Humans↗

Scanning electron microscopy of the tongue papillae in the pig (Sus scrofa).

A clear understanding of the role of different papillae in the pig may permit the development of a more palatable diet, thus, better utilizing anatomical structures and morphological characteristics to enhance health and productivity in this domestic species. The study used ten healthy market-size, mixed-breed pigs to properly describe the surface structure of the tongue papillae using standard scanning electron microscopic techniques. Two types of sharp and blunt filiform papillae were identified. Fungiform papillae, located on the lateral side of the tongue, were circular and large with surface taste pores. The majority of oval papillae on the dorsal surface of the tongue contained multidirectional surface grooves and lacked taste pores. The foliate papillae, located principally on the caudal third and lateral part of the tongue, were comprised of four to five leaves and they had additional pseudopapillae. The two vallate papillae, found in the caudal third and dorsum of the tongue, had a well-defined vallum and pseudopapillae on their surface. At the root of the tongue, two types of conical papillae with or without apex were observed. The entire area covered by conical papillae was deeply occupied by lingual tonsils. The lingual tonsils were scattered with varying sized lymph nodules in the propria mucosa of the conical papillae deep to epithelium. Functionally, the filiform and conical papillae appeared to have a mechanical role whereas fungiform, foliate, and vallate papillae apparently perform a gustatory role in the pig. The tonsillar location at the root of the tongue provides an ideal experimental model for immunohistological and immunological studies on the lymphoid tissue in man.

Animals↗

Reproducing bursting interspike interval statistics of the gustatory cortex.

Cortical neurons in vivo generate highly irregular spike sequences. Recently, it was experimentally found that the local variation of interspike intervals, LV, is nearly constant for every spike sequence for the same neurons. On the contrary, the coefficient of variation, CV, varies over different spike sequences. Here, we first show that these characteristic features are also applicable in bursting spike sequences that are obtained from the rat gustatory cortex. Next, we show that the conventional leaky integrate-and-fire model does not fully account for reproducing these statistical features in data of real bursting spike sequences. We resolve this difficulty by proposing an alternative neuron model which is a reduction of the bursting neuron model involving the persistent sodium current. Our study implies that (1) the characteristic features of CV and LV are the results of the endogenous bursting and (2) the bursting behavior in the gustatory cortex is caused mainly by the persistent sodium current.

Animals↗