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Taste receptors, first described for their gustatory functions within the oral cavity and oropharynx, are now known to be expressed in many organ systems. Even intraoral taste receptors regulate non-sensory pathways, and recent literature has connected bitter taste receptors to various states of health and disease. These extragustatory pathways involve previously unexplored, clinically relevant roles for taste signaling in areas including susceptibility to infection, antibiotic efficacy, and cancer outcomes. Among other physicians, otolaryngologists who manage head and neck diseases should be aware of this growing body of evidence and its relevance to their fields. In this review, we describe the role of extragustatory taste receptors in head and neck health and disease, highlighting recent advances, clinical implications, and directions for future investigation. Additionally, this review will discuss known TAS2R polymorphisms and the associated implications for clinical prognosis. [ABSTRACT FROM AUTHOR]

Rationale: Flavors can alter the orosensory properties of tobacco products. Specifically, flavors can serve as an oral cue for smokeless tobacco products. Objectives: We aimed to investigate the impact of oral vanillin, the principal chemical of vanilla flavor in tobacco products, on nicotine's taste, and nicotine choice, intake, and seeking behaviors. Methods: Experiments were performed in young adult Sprague Dawley rats. We employed a two-bottle free-choice test (2BC) to measure the preference for different concentrations of vanillin and its effect on nicotine preference. To explore the long-term effects of early exposure to sweetened vanillin, we utilized a combined 2BC and intraoral self-administration (IOSA) model. We assessed the nicotine taking and seeking behaviors in the presence or absence of vanillin. We performed a taste reactivity test (TRT) to quantify liking (ingestive) and disliking (aversive) taste responses to oral nicotine with or without vanillin. Results: In 2BC, female rats preferred vanillin containing solutions more than their male counterparts. In IOSA, vanillin alone and in combination with nicotine led to greater IOSA compared to water. Female rats self-administered vanillin plus nicotine more than male rats. Vanillin increased motivation to nicotine taking, but only in females. In TRT, vanillin increased nicotine's ingestive responses but blocked aversive responses in both sexes. Conclusions: These results indicate that vanilla flavor can increase oral nicotine intake. It can also increase liking and decrease disliking of nicotine's taste. Furthermore, the impact of vanilla flavor on nicotine taste and nicotine choice, intake, and seeking behaviors is concentration and sex dependent. [ABSTRACT FROM AUTHOR]

Taste buds contain 2 types of GABA-producing cells: sour-responsive Type III cells and glial-like Type I cells. The physiological role of GABA, released by Type III cells is not fully understood. Here, we investigated the role of GABA released from Type III cells using transgenic mice lacking the expression of GAD67 in taste bud cells (Gad67-cKO mice). Immunohistochemical experiments confirmed the absence of GAD67 in Type III cells of Gad67-cKO mice. Furthermore, no difference was observed in the expression and localization of cell type markers, ectonucleoside triphosphate diphosphohydrolase 2 (ENTPD2), gustducin, and carbonic anhydrase 4 (CA4) in taste buds between wild-type (WT) and Gad67-cKO mice. Short-term lick tests demonstrated that both WT and Gad67-cKO mice exhibited normal licking behaviors to each of the five basic tastants. Gustatory nerve recordings from the chorda tympani nerve demonstrated that both WT and Gad67-cKO mice similarly responded to five basic tastants when they were applied individually. However, gustatory nerve responses to sweet–sour mixtures were significantly smaller than the sum of responses to each tastant in WT mice but not in Gad67-cKO mice. In summary, elimination of GABA signalling by sour-responsive Type III taste cells eliminates the inhibitory cell–cell interactions seen with application of sour–sweet mixtures. [ABSTRACT FROM AUTHOR]

While previous research has shown the potential links between taste perception pathways and brain-related conditions, the area involving Alzheimer's disease remains incompletely understood. Taste perception involves neurotransmitter signaling, including serotonin, glutamate, and dopamine. Disruptions in these pathways are implicated in neurodegenerative diseases. The integration of olfactory and taste signals in flavor perception may impact brain health, evident in olfactory dysfunction as an early symptom in neurodegenerative conditions. Shared immune response and inflammatory pathways may contribute to the association between altered taste perception and conditions like neurodegeneration, present in Alzheimer's disease. This study consists of an exploration of expression-quantitative trait loci (eQTL), utilizing whole-blood transcriptome profiles, of 28 taste perception genes, from a combined cohort of 475 African American subjects. This comprehensive dataset was subsequently intersected with single-nucleotide polymorphisms (SNPs) identified in Genome-Wide Association Studies (GWAS) of Alzheimer's Disease (AD). Finally, the investigation delved into assessing the association between eQTLs reported in GWAS of AD and the profiles of 741 proteins from the Olink Neurological Panel. The eQTL analysis unveiled 3,547 statistically significant SNP-Gene associations, involving 412 distinct SNPs that spanned all 28 taste genes. In 17 GWAS studies encompassing various traits, a total of 14 SNPs associated with 12 genes were identified, with three SNPs consistently linked to Alzheimer's disease across four GWAS studies. All three SNPs demonstrated significant associations with the down-regulation of TAS2R41, and two of them were additionally associated with the down-regulation of TAS2R60. In the subsequent pQTL analysis, two of the SNPs linked to TAS2R41 and TAS2R60 genes (rs117771145 and rs10228407) were correlated with the upregulation of two proteins, namely EPHB6 and ADGRB3. Our investigation introduces a new perspective to the understanding of Alzheimer's disease, emphasizing the significance of bitter taste receptor genes in its pathogenesis. These discoveries set the stage for subsequent research to delve into these receptors as promising avenues for both intervention and diagnosis. Nevertheless, the translation of these genetic insights into clinical practice requires a more profound understanding of the implicated pathways and their pertinence to the disease's progression across diverse populations. [ABSTRACT FROM AUTHOR]

Purpose: gustatory ability is a marker of health not routinely tested in the medical practice. The current study wants to assess whether taste strips can be useful to monitor taste function from home. Methods: we performed simple sensory tests in lab setting vs. unassisted testing at home, and compared the results with self-reports ability to taste and smell. Using paper strips impregnated with sweet, bitter, salty, or sour tastants, and with two trigeminal stimuli (capsaicin, tannins) in high and low concentrations, we assessed gustatory and trigeminal function in 74 participants (47 women) in the lab, where paper strips were administered by an experimenter, and in 77 participants (59 women) at home, where they self-administered the test. Results: we found that high (but not low) concentration taste strips are correctly identified by vast majority of participants. On average, taste identification, intensity and pleasantness scores did not differ for the 8 taste strips, while identification of capsaicin was significantly better in the lab. Taste identification scores correlated with intensity ratings in both settings (r = 0.56, in the lab, r = 0.48, at home, p < 0.005). Self-rated taste ability correlated with self-rated smell ability (r = 0.68, and r = 0.39, p ≤ 0.005), but not with scores in the strips test. Conclusion: home testing with impregnated taste strips is feasible, and can be used for telemedical purposes. [ABSTRACT FROM AUTHOR]

Sucrose provides both sweetness and energy by binding to both Venus flytrap domains (VFD) of the heterodimeric sweet taste receptor (T1R2/T1R3). In contrast, non-caloric sweeteners such as sucralose and aspartame only bind to one specific domain (VFD2) of T1R2, resulting in high-intensity sweetness. In this study, we investigate the binding mechanism of various steviol glycosides, artificial sweeteners, and a negative allosteric modulator (lactisole) at four distinct binding sites: VFD2, VFD3, transmembrane domain 2 (TMD2), and TMD3 through binding experiments and computational docking studies. Our docking results reveal multiple binding sites for the tested ligands, including the radiolabeled ligands. Our experimental evidence demonstrates that the C20 carboxy terminus of the Gα protein can bind to the intracellular region of either TMD2 or TMD3, altering GPCR affinity to the high-affinity state for steviol glycosides. These findings provide a mechanistic understanding of the structure and function of this heterodimeric sweet taste receptor. Sucrose and other non-caloric sweeteners can bind to different domains of the heterodimeric sweet taste receptor (T1R2/T1R3), resulting in different levels of sweetness. Here, the authors investigate the binding mechanism of various steviol glycosides, artificial sweeteners, and a negative allosteric modulator (lactisole) at four distinct binding sites of T1R2/T1R3 through binding experiments and computational docking studies, revealing multiple binding sites for the tested ligands and structural– function correlations of ligand–receptor interactions. [ABSTRACT FROM AUTHOR]

Disorders of gallbladder motility can lead to serious pathology. Bitter tastants acting upon bitter taste receptors (TAS2R family) have been proposed as a novel class of smooth muscle relaxants to combat excessive contraction in the airways and other organs. To explore whether this might also emerge as an option for gallbladder diseases, we here tested bitter tastants for relaxant properties and profiled Tas2r expression in the mouse gallbladder. In organ bath experiments, the bitter tastants denatonium, quinine, dextromethorphan, and noscapine, dose-dependently relaxed the pre-contracted gallbladder. Utilizing gene-deficient mouse strains, neither transient receptor potential family member 5 (TRPM5), nor the Tas2r143/Tas2r135/Tas2r126 gene cluster, nor tuft cells proved to be required for this relaxation, indicating direct action upon smooth muscle cells (SMC). Accordingly, denatonium, quinine and dextromethorphan increased intracellular calcium concentration preferentially in isolated gallbladder SMC and, again, this effect was independent of TRPM5. RT-PCR revealed transcripts of Tas2r108, Tas2r126, Tas2r135, Tas2r137, and Tas2r143, and analysis of gallbladders from mice lacking tuft cells revealed preferential expression of Tas2r108 and Tas2r137 in tuft cells. A TAS2R143-mCherry reporter mouse labeled tuft cells in the gallbladder epithelium. An in silico analysis of a scRNA sequencing data set revealed Tas2r expression in only few cells of different identity, and from in situ hybridization histochemistry, which did not label distinct cells. Our findings demonstrate profound tuft cell- and TRPM5-independent relaxing effects of bitter tastants on gallbladder smooth muscle, but do not support the concept that these effects are mediated by bitter receptors. [ABSTRACT FROM AUTHOR]

Sour taste is detected by type III taste receptor cells that generate membrane depolarization with action potentials in response to HCl applied to the apical membranes. The shape of action potentials in type III cells exhibits larger afterhyperpolarization due to activation of transient A-type voltage-gated K+ currents. Although action potentials play an important role in neurotransmitter release, the electrophysiological features of A-type K+ currents in taste buds remain unclear. Here, we examined the electrophysiological properties of A-type K+ currents in mouse fungiform taste bud cells using in-situ whole-cell patch clamping. Type III cells were identified with SNAP-25 immunoreactivity and/or electrophysiological features of voltage-gated currents. Type III cells expressed A-type K+ currents which were completely inhibited by 10 mM TEA, whereas IP3R3-immunoreactive type II cells did not. The half-maximal activation and steady-state inactivation of A-type K+ currents were 17.9 ± 4.5 (n = 17) and − 11.0 ± 5.7 (n = 17) mV, respectively, which are similar to the features of Kv3.3 and Kv3.4 channels (transient and high voltage-activated K+ channels). The recovery from inactivation was well fitted with a double exponential equation; the fast and slow time constants were 6.4 ± 0.6 ms and 0.76 ± 0.26 s (n = 6), respectively. RT-PCR experiments suggest that Kv3.3 and Kv3.4 mRNAs were detected at the taste bud level, but not at single-cell levels. As the phosphorylation of Kv3.3 and Kv3.4 channels generally leads to the modulation of cell excitability, neuromodulator-mediated A-type K+ channel phosphorylation likely affects the signal transduction of taste. [ABSTRACT FROM AUTHOR]

This paper introduces the Virtual Taste Interface, a digital control system that simulates the sensation of taste (gustation) on humans. Our approach studies electrical and thermal stimulation on the tip of the human tongue to produce different taste sensations. It consists of two modules: a control system and a specially designed separate module to attach to a user's tongue. Several experimental studies were conducted with human participants based on 1) different properties of electrical stimulation such as the magnitude of current and frequency, 2) temperature change (heating and cooling), and 3) hybrid stimulation by combining both electrical and thermal stimulation. Experimental results show that the system successfully generates salty, sour, and bitter tastes among the five basic taste sensations (i.e., salty, sour, sweet, bitter, and umami). This approach deserves future investigation as the reported sensations show subjective results on a few occasions and to further study the evidence of actuating sweet taste through thermal stimulation. The novelty of this work primarily has three aspects: 1) studying the simulation and control of taste sensations achievable through the Virtual Taste Interface against the properties of electric current and change in temperature, 2) the methods of actuating taste sensations by electrical and thermal stimulation methods, either individually or in combination, and 3) the aim of introducing the human sense of taste as a digitally controllable media. [ABSTRACT FROM AUTHOR]

Rationale: The ad-libitum taste test is a widely used covert measure of motivation to consume alcohol in the laboratory. However, studies on its construct validity and potential confounding factors are scarce. Objectives: This study aimed to evaluate the construct validity of the ad-libitum taste test by examining the association of ad-libitum alcohol consumption with typical alcohol use and craving, and investigating potential moderation by trait anxiety, depressiveness, current mood, and drinking motives. Methods: A sample of 264 young male individuals were offered two 0.33 l glasses of beer. Participants were instructed to rate the characteristics of each drink, while the percentage of beverages containing alcohol consumed was assessed. Associations of ad-libitum consumption with typical alcohol use and craving were assessed using non-parametric and piecewise regressions. Moreover, moderator analysis with trait anxiety, depressiveness, current mood, and drinking motives was carried out. Results: Ad-libitum alcohol consumption was associated with typical alcohol use and alcohol craving. However, these associations decreased at high consumption levels. Associations between ad-libitum consumption, typical alcohol use, and craving were stable across several conditions, except that the association between ad-libitum consumption and craving increased with higher social, conformity, and coping drinking motives. Conclusions: The ad-libitum taste test appears to be a valid measure of the motivation to drink alcohol in laboratory studies in young male adults, although this validity might be compromised at high levels of ad-libitum consumption. Consideration of these factors can contribute to further refining the ad-libitum taste test as a valuable tool for assessing motivation to consume alcohol in laboratory studies. [ABSTRACT FROM AUTHOR]

Taste is a vital chemical sense for feeding behaviour. In mammals, the umami and sweet taste receptors comprise three members of the taste receptor type 1 (T1R/TAS1R) family: T1R1, T1R2 and T1R3. Because their functional homologues exist in teleosts, only three TAS1R genes generated by gene duplication are believed to have been inherited from the common ancestor of bony vertebrates. Here, we report five previously uncharacterized TAS1R members in vertebrates, TAS1R4, TAS1R5, TAS1R6, TAS1R7 and TAS1R8, based on genome-wide survey of diverse taxa. We show that mammalian and teleost fish TAS1R2 and TAS1R3 genes are paralogues. Our phylogenetic analysis suggests that the bony vertebrate ancestor had nine TAS1Rs resulting from multiple gene duplications. Some TAS1Rs were lost independently in descendent lineages resulting in retention of only three TAS1Rs in mammals and teleosts. Combining functional assays and expression analysis of non-teleost fishes we show that the novel T1Rs form heterodimers in taste-receptor cells and recognize a broad range of ligands such as essential amino acids, including branched-chain amino acids, which have not been previously considered as T1R ligands. This study reveals diversity of taste sensations in both modern vertebrates and their ancestors, which might have enabled vertebrates to adapt to diverse habitats on Earth., (© 2023. The Author(s).)

Sweet taste is the most powerful taste modality shaping feeding behavior and influencing homeostasis. This review summarizes data on the reception and encoding of taste signals at the level of taste buds and cerebral centers during the consumption of sweet substances. The main focus of attention is on the molecular and cellular mechanisms underlying identification of sweet taste and detection of the caloric composition of food, including the role of T1R2/T1R3 membrane protein receptors and the associated intracellular enzyme cascade, along with the metabolic mechanism assessing the concentration of glucose entering the cytoplasm. The genetic aspects of sensitivity to sweetness and the influence of sweet taste receptor gene polymorphism on sensitivity to sugars and low-calorie sweeteners are described. We present results from current studies of the endocrine, paracrine, and autocrine modulation of the reception and perception of sweet taste depending on the metabolic status of the body. A suggestion is made regarding a promising direction of research in this area. [ABSTRACT FROM AUTHOR]

The vertebrate sense of taste allows rapid assessment of the nutritional quality and potential presence of harmful substances prior to ingestion. Among the five basic taste qualities, salty, sour, sweet, umami, and bitter, bitterness is associated with the presence of putative toxic substances and elicits rejection behaviors in a wide range of animals including humans. However, not all bitter substances are harmful, some are thought to be health-beneficial and nutritious. Among those compound classes that elicit a bitter taste although being non-toxic and partly even essential for humans are bitter peptides and l-amino acids. Using functional heterologous expression assays, we observed that the 5 dominant human bitter taste receptors responsive to bitter peptides and amino acids are activated by bile acids, which are notorious for their extreme bitterness. We further demonstrate that the cross-reactivity of bitter taste receptors for these two different compound classes is evolutionary conserved and can be traced back to the amphibian lineage. Moreover, we show that the cross-detection by some receptors relies on "structural mimicry" between the very bitter peptide l-Trp-Trp-Trp and bile acids, whereas other receptors exhibit a phylogenetic conservation of this trait. As some bile acid-sensitive bitter taste receptor genes fulfill dual-roles in gustatory and non-gustatory systems, we suggest that the phylogenetic conservation of the rather surprising cross-detection of the two substance classes could rely on a gene-sharing-like mechanism in which the non-gustatory function accounts for the bitter taste response to amino acids and peptides. [ABSTRACT FROM AUTHOR]

Marine bioactive peptides (MBPs) are widely applied in functional foods and medicine industries. Several studies indicate that MBP consumption may play a vital role in the body's health due to their biological properties such as antioxidant, anti-inflammatory, and ACE-inhibitory activities. However, the majority of MBPs have numerous limitations, including bitter taste, stability, and unfavorable bioactivity. Recently, chemical and physical modifications have been commonly used to solve these limitations. Modification of MBPs, which involves using novel techniques, was discussed in this review. This review displayed that MBP properties, including biological activity, stability, and taste properties, were improved after modification mainly by encapsulation and chemical reaction. In particular, the results showed that the biological properties (antioxidant, anti-inflammatory, ACE-inhibitory, and antimicrobial activities) of the modified MBPs were higher than unmodified ones. In addition, the taste of MBPs, especially volatile flavor, was also enhanced after modification. Furthermore, modified MBPs may have to remain stable during food processing, storage, and in the host mouth and stomach for absorption in the small intestine. Therefore, modification of MBPs is an effective approach to protect and improve MBP properties. Finally, food matrix interactions and in vivo studies of modified MBPs are needed in the future. [ABSTRACT FROM AUTHOR]

Background/objectives: Adherence to dietary recommendations is a critical component in the management of type 1 diabetes (T1D). Taste and flavor significantly influence food choices. The aim of this study was to investigate taste sensitivity and flavor recognition ability in adults with T1D compared to healthy individuals. Subjects/methods: Seventy-two people with T1D and 72 matched healthy controls participated in the study. Participants underwent the gustometry test for sweet, sour, salty, and bitter tastes and the flavor test, which consisted of oral administration of aqueous aromatic solutions identifying 21 different compounds. Results: Participants with T1D had significantly lower flavor scores and gustometry scores than controls (p < 0.0001 and p = 0.0063, respectively). T1D individuals showed a lower perception of sour, bitter and salty tastes than controls, while the perception of sweet taste was similar. The sex differences and age-related decline in flavor perception observed in controls were not present in the participants with T1D. Neither BMI nor disease-related parameters such as fasting blood glucose on the day of the study, glycosylated hemoglobin, age at onset of diabetes, duration of diabetes, or type of insulin treatment (insulin pump or multiple daily injections) correlated with flavor and taste perception in the T1D participants. Conclusions: Flavor and taste perception are impaired in adults with T1D, potentially affecting dietary adherence and food choices. This highlights the need for further research into the mechanisms underlying sensory changes in T1D and emphasizes the importance of targeted dietary interventions to improve health outcomes and quality of life in this population. [ABSTRACT FROM AUTHOR]

Taste, a pivotal sense modality, plays a fundamental role in discerning flavors and evaluating the potential harm of food, thereby contributing to human survival, physical and mental health. Patients with tongue cancer may experience a loss of taste following extensive surgical resection with flap reconstruction. Here, we designed a gustatory interface that enables the non-invasive detection of tongue electrical activities for a comprehensive operative assessment. Moreover, it decodes gustatory information from the reconstructed tongue without taste buds. Our gustatory interface facilitates the recording and analysis of electrical activities on the tongue, yielding an electrical mapping across the entire tongue surface, which delineates the safe margin for surgical management and assesses flap viability for postoperative structure monitoring and prompt intervention. Furthermore, the gustatory interface helps patients discern tastes with an accuracy of 97.8%. Our invention offers a promising approach to clinical assessment and management and holds potential for improving the quality of life for individuals with tongue cancer. Cancer patients suffer from dysgeusia. Here, the authors propose a gustatory interface for operative assessment and taste decoding, offering potential to improve the quality of life of individuals suffering from tongue cancer. [ABSTRACT FROM AUTHOR]

Intense environmental pressures can yield both regressive and constructive traits through complex evolutionary mechanisms. Although regression is well-studied, the biological bases of constructive features are less well understood. Cave-dwelling Astyanax fish harbor prolific extraoral taste buds on their heads, which are absent in conspecific surface-dwellers. Here, we present novel ontogenetic data demonstrating extraoral taste buds appear gradually and late in life history. This appearance is similar but non-identical in different cavefish populations, where patterning has evolved to permit taste bud re-specification across the endoderm-ectoderm germ layer boundary. Quantitative genetic analyses revealed that spatially distinct taste buds on the head are primarily mediated by two different cave-dominant loci. While the precise function of this late expansion on to the head is unknown, the appearance of extraoral taste buds coincides with a dietary shift from live-foods to bat guano, suggesting an adaptive mechanism to detect nutrition in food-starved caves. This work provides fundamental insight to a constructive evolutionary feature, arising late in life history, promising a new window into unresolved features of vertebrate sensory organ development.Long-term developmental and genetic studies reveal that extraoral taste buds on the head develop late into life history in different populations of cave-dwelling fish, and are mediated by two principal genetic loci. [ABSTRACT FROM AUTHOR]

A subset of gustatory cells are serotonin immunoreactive (ir) in the mammalian taste bud. In the taste bud of lamprey, elongated gustatory-like cells are also serotonin-ir. In contrast, flattened serotonin-ir cells are located only in the basal region of the taste buds in the teleosts and amphibians. These serotonin-ir cells are termed as basal cells. To evaluate the evolution and diversity of serotonergic cells in the taste bud of amniote animals, we explored the distribution and morphology of serotonin-ir cells in the taste buds of ancestral actinopterygian fish (spotted gar, sturgeon, Polypterus senegalus) and elasmobranch (stingray). In all examined animals, the taste buds contained serotonin-ir cells in their basal part. The number of serotonin-ir basal cells in each taste bud was different between these fish species. They were highest in the stingray and decreased in the order of the Polypterus, sturgeon, and gar. While serotonin immunoreactivity was observed only in the basal cells in the taste buds of the ancestral actinopterygian fish, some elongated cells were also serotonin-ir in addition to the basal cells in the stingray taste buds. mRNA of tryptophan hydroxylase 1 (tph1), a rate-limiting enzyme of the serotonin synthesis, is expressed in both the elongated and basal cells of stingray taste buds, indicating that these cells synthesize the serotonin by themselves. These results suggest that the serotonin-ir basal cells arose from the ancestor of the cartilaginous fish, and serotonin-ir cells in the elasmobranch taste bud exhibit an intermediate aspect between the lamprey and actinopterygian fish. [ABSTRACT FROM AUTHOR]

Taste perception plays a pivotal role in guiding nutrient intake and aiding in the avoidance of potentially harmful substances through five basic tastes - sweet, bitter, umami, salty, and sour. Taste perception originates from molecular interactions in the oral cavity between taste receptors and chemical tastants. Hence, the recognition of taste receptors and the subsequent perception of taste heavily rely on the physicochemical properties of food ingredients. In recent years, several advances have been made towards the development of machine learning-based algorithms to classify chemical compounds' tastes using their molecular structures. Despite the great efforts, there remains significant room for improvement in developing multi-class models to predict the entire spectrum of basic tastes. Here, we present a multi-class predictor aimed at distinguishing bitter, sweet, and umami, from other taste sensations. The development of a multi-class taste predictor paves the way for a comprehensive understanding of the chemical attributes associated with each fundamental taste. It also opens the potential for integration into the evolving realm of multi-sensory perception, which encompasses visual, tactile, and olfactory sensations to holistically characterize flavour perception. This concept holds promise for introducing innovative methodologies in the rational design of foods, including pre-determining specific tastes and engineering complementary diets to augment traditional pharmacological treatments. [ABSTRACT FROM AUTHOR]

To evaluate the effect of decreased salivary secretion on taste preference, we investigated taste preference for five basic tastes by a 48 h two-bottle preference test using a mouse model (desalivated mice) that underwent surgical removal of three major salivary glands: the parotid, submandibular, and sublingual glands. In the desalivated mice, the avoidance behaviors for bitter and salty tastes and the attractive behaviors for sweet and umami tastes were significantly decreased. We confirmed that saliva is necessary to maintain normal taste preference. To estimate the cause of the preference changes, we investigated the effects of salivary gland removal on the expression of taste-related molecules in the taste buds. No apparent changes were observed in the expression levels or patterns of taste-related molecules after salivary gland removal. When the protein concentration and composition in the saliva were compared between the control and desalivated mice, the protein concentration decreased and its composition changed after major salivary gland removal. These results suggest that changes in protein concentration and composition in the saliva may be one of the factors responsible for the changes in taste preferences observed in the desalivated mice. [ABSTRACT FROM AUTHOR]

Rationale: Muscarinic receptor activity in the basolateral amygdala (BLA) is known to be involved in plasticity mechanisms that underlie emotional learning. The BLA is involved in the Attenuation of Neophobia, an incidental taste learning task in which a novel taste becomes familiar and recognized as safe. Objective: Here we assessed the role of muscarinic receptor activity in the BLA in incidental taste learning. Methods: Young adult male Wistar rats were bilaterally implanted with cannulas aimed at BLA. After recovery, rats were randomly assigned to either vehicle or muscarinic antagonist group, for each experiment. We tested the effect of specific and non-specific muscarinic antagonists administered either 1) 20 min before novel taste presentation; 2) immediately after novel taste presentation; 3) immediately after retrieval (the second taste presentation on Day 5 -S2-) or immediately after the fifth taste presentation on Day 8 (S5). Results: Non-specific muscarinic receptor antagonist scopolamine infused prior to novel taste, while not affecting novel taste preference, abolished AN, i.e., the increased preference observed in control animals on the second presentation. When administered after taste consumption, intra-BLA scopolamine not only prevented AN but caused a steep decrease in the taste preference on the second presentation. This scopolamine-induced taste avoidance was not dependent on taste novelty, nor did it generalize to another novel taste. Targeting putative postsynaptic muscarinic receptors with specific M1 or M3 antagonists appeared to produce a partial taste avoidance, while M2 antagonism had no effect. Conclusion: These data suggest that if a salient gustatory experience is followed by muscarinic receptors antagonism in the BLA, it will be strongly and persistently avoided in the future. The study also shows that scopolamine is not just an amnesic drug, and its cognitive effects may be highly dependent on the task and the structure involved. [ABSTRACT FROM AUTHOR]

Bitter taste receptors (TAS2Rs), a subfamily of G-protein coupled receptors (GPCRs) expressed orally and extraorally, elicit signaling in response to a large set of tastants. Among 25 functional TAS2Rs encoded in the human genome, TAS2R14 is the most promiscuous, and responds to hundreds of chemically diverse ligands. Here we present the cryo–electron microscopy (cryo-EM) structure of the human TAS2R14 in complex with its signaling partner gustducin, and bound to flufenamic acid (FFA), a clinically approved nonsteroidal anti-inflammatory drug. The structure reveals an unusual binding mode, where two copies of FFA are bound at distinct pockets: one at the canonical receptor site within the trans-membrane bundle, and the other in the intracellular facet, bridging the receptor with gustducin. Together with a pocket-specific BRET-based ligand binding assay, these results illuminate bitter taste signaling and provide tools for a site-targeted compound design. Bitter taste receptors (TAS2Rs) are a subfamily of G-protein coupled receptors (GPCRs). Here, the authors report a cryo-EM structure of the human TAS2R14 in complex with its signaling partner gustducin, and bound to an anti-inflammatory drug flufenamic acid (FFA). [ABSTRACT FROM AUTHOR]

Mammalian taste bud cells are composed of several distinct cell types and differentiated from surrounding tongue epithelial cells. However, the detailed mechanisms underlying their differentiation have yet to be elucidated. In the present study, we examined an Ascl1-expressing cell lineage using circumvallate papillae (CVP) of newborn mice and taste organoids (three-dimensional self-organized tissue cultures), which allow studying the differentiation of taste bud cells in fine detail ex vivo. Using lineage-tracing analysis, we observed that Ascl1 lineage cells expressed type II and III taste cell markers both CVP of newborn mice and taste organoids. However, the coexpression rate in type II cells was lower than that in type III cells. Furthermore, we found that the generation of the cells which express type II and III cell markers was suppressed in taste organoids lacking Ascl1-expressing cells. These findings suggest that Ascl1-expressing precursor cells can differentiate into both type III and a subset of type II taste cells. [ABSTRACT FROM AUTHOR]

For humans, taste is essential for perceiving the nutrient content or harmful components of food. The current method of taste sensory evaluation relies on artificial sensory evaluation and an electronic tongue. The former has strong subjectivity and poor repeatability, and the latter is not sufficiently flexible. To decode people's objective taste perception, a strategy for acquiring and recognizing four classes (sour, sweet, bitter, and salty) in taste-related electroencephalograms (EEGs) was proposed. First, according to the proposed experimental paradigm, the taste-related EEGs of subjects under different taste stimulations were collected. Second, to avoid insufficient training of the model due to the small number of EEG samples, a temporal and spatial reconstruction data augmentation (TSRDA) method was proposed, effectively augmenting taste-related EEGs by reconstructing the important features in temporal and spatial dimensions. Third, a multiview channel attention (MVCA) module was introduced into a designed convolutional neural network to extract the important features of the augmented EEG. The proposed method had an accuracy of 99.56%, F1 score of 99.48%, and kappa value of 99.38%, showing the method's ability to successfully decoded sour, sweet, bitter, and salty EEG signals. In conclusion, combining TSRDA with EEG technology provides an objective and effective method for the sensory evaluation of food taste. [ABSTRACT FROM AUTHOR]

Abstract Several approaches have been proposed to obtain successful models to solve complex next-item recommendation problem in non-prohibitive computational time, such as by using heuristics, designing architectures, and applying information filtering techniques. In the current technological scenario of artificial intelligence, sequential recommender systems have been gaining attention and they are a highly demanding research area, especially using deep learning in their development. Our research focuses on an efficient and practical model for managing sequential session-based recommendations of specific products for users using the wine and movie domains as case studies. Through an innovative recommender model called X-Model4Rec – eXtensible Model for Recommendation, we explore the user's dynamic taste profile using architectures with transformer and multi-head attention mechanisms to solve the next-item recommendation problem. The performance of the proposed model is compared to that of classical and baseline recommender models on two real-world datasets of wines and movies, and the results are better for most of the evaluation metrics.

Taste dysfunction has been associated with chronic kidney disease (CKD) especially end stage kidney disease (ESKD) and also implicated as one of the predisposing factors for the prevalent malnutrition, muscle wasting and impaired quality of life among patients with CKD. To assess the taste function and determine the pattern of taste dysfunction in patients with CKD attending the University College Hospital, Ibadan. This was a cross sectional, hospital-based case–control study of adult patients with CKD. The control group were age and sex matched without CKD. Interviewer-assisted questionnaires were administered on all participants to obtain clinical information concerning demographics, clinical data on kidney disease and taste dysfunction. The four basic taste modalities namely; sweet, sour, bitter and salt taste senses of the participants were tested with validated "taste strips". There were 100 patients with CKD and 100 healthy controls, age ranges between 19 and 86 years (mean ± SD = 46.3 ± 13.9 years) and 20 and 85 years (mean ± SD = 43.4 ± 14.9 years), respectively. There was no statistically significant difference between cases and control gender distribution (p = 0.57). Hypogeusia was found in 27.0% of CKD patients with specific taste modalities dysfunction for salt, sour, sweet and bitter taste of 13.0, 24.0, 13.0 and 17.0%, respectively. The controls only had specific taste modalities dysfunction for salt, sour and bitter taste of 1.0% for each of the taste modalities. The mean total taste scores in the cases and controls were − 9.8 ± 3.2 and 13.4 ± 1.5 (p = 0.001), respectively. The mean taste scores were significantly lower among the cases than controls, salt taste-2.82 ± 1.1 and 3.7 ± 0.7 (p = 0.001), sour taste − 2.2 ± 1.0 and 3.2 ± 0.7 (p = 0.001), sweet taste-, 2.9 ± 1.8 and 3.8 ± 0.5 (p = 0.001), bitter taste − 1.9 ± 1.2 and 2.8 ± 0.9 (p = 0.001). Taste dysfunction is prevalent among patients with CKD and the affectation involves all taste modalities. [ABSTRACT FROM AUTHOR]

Taste stimulation has rehabilitative value in dysphagia management, as it activates salient underlying afferent pathways to swallowing which may evoke feedforward effects on swallow biomechanics. Despite its potential beneficial effects on swallow physiology, taste stimulation's clinical application is limited for persons unsafe to orally consume food/liquid. This study aimed to create edible, dissolvable taste strips matched to flavor profiles previously used in research assessing taste's effects on swallowing physiology and brain activity, and to evaluate how similar their perceived intensity and hedonic, or palatability, ratings were between their liquid counterparts. Plain, sour, sweet–sour, lemon, and orange flavor profiles were custom-made in taste strips and liquid modalities. The generalized Labeled Magnitude Scale and hedonic generalized Labeled Magnitude Scale were used to assess intensity and palatability ratings for flavor profiles in each modality. Healthy participants were recruited and stratified across age and sex. Liquids were rated as more intense than taste strips; however, there was no difference in palatability ratings between the modalities. There were significant differences across flavor profiles in intensity and palatability ratings. Collapsed across liquid and taste strip modalities, pairwise comparisons revealed all flavored stimuli were rated as more intense than the plain profile, sour was perceived as more intense and less palatable than all other profiles, and orange was rated as more palatable than sour, lemon, and plain tastants. Taste strips have useful implications for dysphagia management, as they could offer safe and patient-preferred flavor profiles to potentially provide advantageous swallowing and neural hemodynamic responses. [ABSTRACT FROM AUTHOR]

One of the main problems in medical practice is the lack of patient adherence to treatment, which is often attributed to the bitterness or sourness of medicines causing discomfort and an aversion during administration, especially in children. Therefore, masking an unpleasant taste is one of the goals of pharmaceutical development. Currently, there are various approaches to improving the taste of oral dosage forms containing bitter or excessively sour pharmaceutical substances. This review covers some of these approaches and their advantages and disadvantages and provides relevant examples of the possible use of each of them. [ABSTRACT FROM AUTHOR]

Introduction: No studies have reported data on 3-year prevalence and recovery rates of self-reported COVID-19-related olfactory and gustatory dysfunction. The aim of the present study was to estimate the 3-year prevalence and recovery rate of self-reported COVID-19-related chemosensory dysfunction in a cohort of patients with antecedent mild COVID-19. Methods: This is a prospective observational study, measuring the prevalence of altered sense of smell or taste at follow-up and their variation from baseline, on adult patients consecutively assessed at Treviso and Trieste University Hospitals, who tested positive for SARS-CoV-2 RNA by polymerase chain reaction during March 2020. Results: Overall, out of 403 respondents, 267 patients (66.3%) reported an altered sense of smell or taste (SNOT-22 > 0) at baseline, while 56 (13.9%), 29 (7.2%), and 21 (5.2%) reported such alterations at 6–24 months, 2 years, and 3 years, respectively. Among the 267 patients with COVID-19-associated smell or taste dysfunction at baseline, 246 (92.1%) reported complete resolution at 3 years. Of the patients who still experienced smell or taste dysfunction 2 years after COVID-19, 27.6% and 37.9% recovered completely and partially, respectively, at the 3-year follow-up. Conclusion: Among subjects with antecedent mildly symptomatic SARS-CoV-2 infection, the 3-year prevalence and recovery rate of COVID-19-related alteration in sense of smell or taste was 5% and 92%, respectively. In approximately two-thirds of patients experiencing chemosensory dysfunction still 2 years after COVID-19, it is still possible to observe a delayed complete or partial recovery after a period of 3 years, while the remaining one-third of individuals continues to have unchanged persistent chemosensory alteration. [ABSTRACT FROM AUTHOR]

Purpose: Olfactory dysfunction (OD) commonly accompanies coronavirus disease 2019 (COVID-19). We investigated the kinetics of OD resolution following SARS-CoV-2 infection (wild-type and alpha variant) and its impact on quality of life, physical and mental health. Methods: OD prevalence was assessed in an ambulatory COVID-19 survey (n = 906, ≥ 90 days follow-up) and an observational cohort of ambulatory and hospitalized individuals (n = 108, 360 days follow-up). Co-occurrence of OD with other symptoms and effects on quality of life, physical and mental health were analyzed by multi-dimensional scaling, association rule mining and semi-supervised clustering. Results: Both in the ambulatory COVID-19 survey study (72%) and the observational ambulatory and hospitalized cohort (41%) self-reported OD was frequent during acute COVID-19. Recovery from self-reported OD was slow (survey: median 28 days, observational cohort: 90 days). By clustering of the survey data, we identified a predominantly young, female, comorbidity-free group of convalescents with persistent OD and taste disorders (median recovery: 90 days) but low frequency of post-acute fatigue, respiratory or neurocognitive symptoms. This smell and taste disorder cluster was characterized by a high rating of physical performance, mental health, and quality of life as compared with convalescents affected by prolonged fatigue or neurocognitive complaints. Conclusion: Our results underline the heterogeneity of post-acute COVID-19 sequelae calling for tailored management strategies. The persistent smell and taste disorder phenotype is characterized by good clinical, physical, and mental recovery and may pose a minor challenge for public health. Study registration: ClinicalTrials.gov: NCT04661462 (survey study), NCT04416100 (observational cohort). [ABSTRACT FROM AUTHOR]

Although many patients suffer from taste disorder, methods to improve taste sensitivity are limited. To develop a taste recall training method to improve the perception of taste, 42 healthy individuals were randomly assigned to either the training or the control group. Using the filter paper disc method, participants in the training group were asked to match the four tastes (sweetness, saltiness, sourness, and bitterness) between those of taste recognition thresholds and those of a one-step higher concentration until they get them right. Then, they were asked to match the four tastes between those of one-step lower and one-step higher in concentration from their taste recognition thresholds until they get them right. Finally, they were asked to match the four tastes between those of one-step lower concentration and those of their taste recognition thresholds until they get them right. This training was repeated until perfectly matched. The taste recall training program led to a lowered taste recognition threshold in healthy adults for each taste quality, suggesting the improvement of taste sensitivity. This lowered threshold for each taste was observed with each additional training session. We conclude that this taste recall training method might be a therapeutic approach for treating taste disorder. [ABSTRACT FROM AUTHOR]

Purpose: Night shift workers are at risk of making poor food choices: e.g. sleep deprivation may lead to higher food intake with innate preferred tastes, such as sweet, savoury and fatty foods. Therefore, better insight in dietary taste patterns of night shift workers may improve the understanding of their food choices. Methods: This observational study assessed dietary taste patterns of 120 female night shift working nurses and compared them to 307 women of a reference population. Dietary intake, assessed with 24-h dietary recalls, was combined with a taste intensity database, including taste profiles of 557 foods. The contribution to the daily intake of 6 taste clusters was assessed: fat, neutral, sweet/fat, sweet/sour, salt/umami/fat and bitter. Results: During night shifts, nurses consumed a significantly higher energy percentage (en%) of 'neutral' (5.9 en%), 'sweet/sour' (8.1 en%) and 'sweet/fat' (6.5 en%) tasting foods and a lower en% of 'fat' (− 17.1 en%) and 'bitter' (− 2.1 en%) tasting foods than outside the night shift. They consumed a larger en% from foods with a 'sweet/sour' (1.9 en%) taste and a lower en% from foods with a 'bitter' (− 2.1 en%) taste than the reference population, irrespective of age, BMI and smoking status. A higher en% and gram% of 'fat' tasting foods and a higher gram% 'fat/salt/umami' tasting foods were associated with lower diet quality. Conclusion: Our results only partly support our hypothesis that nurses would select foods with more innate taste preferences. In addition, fat and savoury tasting foods were negatively associated with their diet quality. [ABSTRACT FROM AUTHOR]

Objective: Exploring the experiences and perceptions of head and neck cancer (HNC) patients undergoing proton heavy ion therapy who develop taste dysfunction during treatment to improve taste dysfunction management for these patients. Design: A qualitative study design using a descriptive phenomenological approach. Method: Conducted individual face-to-face semi-structured interviews in the Head and Neck Tumor Department of the Shanghai Proton and Heavy Ion Center from February to April 2024. Results: The experiences of patients with HNC undergoing proton and heavy ion radiotherapy revealed four key themes: the diversity of taste dysfunction (including reduced or lost perception of sweet, sour, bitter, and other tastes, as well as altered and distorted taste of certain foods); the impact of taste dysfunction on quality of life (changes in dietary habits, malnutrition and weight fluctuations, mental health, and social impacts); strategies for coping with taste dysfunction (altering dietary habits and increasing the use of seasonings to compensate for taste reduction, seeking social support, and engaging in mental health activities to manage emotional distress); and expectations from the healthcare team (need for information and support, psychological support services, and monitoring and evaluation). Conclusion: Patients with HNC undergoing proton and heavy ion therapy experience significant taste dysfunction. Therefore, during proton and heavy ion therapy for HNC, it is crucial to closely monitor and effectively manage taste dysfunction to enhance patients’ quality of life and treatment outcomes. Future research should further explore the mechanisms of taste dysfunction and develop interventions to better meet patients’ needs and improve the individualization of treatment. [ABSTRACT FROM AUTHOR]

Purpose: To estimate long-term prognosis of chemosensory dysfunctions among patients recovering from COVID-19 disease. Methods: Between April 2020 and July 2022, we conducted a prospective, observational study enrolling 48 patients who experienced smell and/or taste dysfunction during the acute-phase of COVID-19. Patients were evaluated for chemosensory function up to 24 months after disease onset. Results: During the acute-phase of COVID-19, 80% of patients reported anosmia, 15% hyposmia, 63% ageusia, and 33% hypogeusia. At two years' follow-up, 53% still experienced smell impairment, and 42% suffered from taste impairment. Moreover, 63% of patients who reported parosmia remained with olfactory disturbance. Interestingly, we found a negative correlation between visual analogue scale scores for smell and taste impairments during the acute-phase of COVID-19 and the likelihood of long-term recovery. Conclusion: Our study sheds light on the natural history and long-term follow-up of chemosensory dysfunction in patients recovering from COVID-19 disease. Most patients who initially suffered from smell and/or taste disturbance did not reach full recovery after 2 years follow-up. The severity of impairment may serve as a prognostic indicator for full recovery. [ABSTRACT FROM AUTHOR]

Increased sugar intake and taste dysfunction have been reported in patients with inflammatory bowel disease (IBD), a chronic disorder characterized by diarrhea, pain, weight loss and fatigue. It was previously unknown whether taste function changes in mouse models of IBD. Mice consumed dextran sodium sulfate (DSS) during three 7-day cycles to induce chronic colitis. DSS-treated mice displayed signs of disease, including significant weight loss, diarrhea, loss of colon architecture, and inflammation of the colon. After the last DSS cycle we assessed taste function by recording electrophysiological responses from the chorda tympani (CT) nerve, which transmits activity from lingual taste buds to the brain. DSS treatment significantly reduced neural taste responses to natural and artificial sweeteners. Responses to carbohydrate, salt, sour or bitter tastants were unaffected in mice with colitis, but umami responses were modestly elevated. DSS treatment modulated the expression of receptor subunits that transduce sweet and umami stimuli in oral taste buds as a substrate for functional changes. Dysregulated systemic cytokine responses or dysbiosis that occurs during chronic colitis may be upstream from changes in oral taste buds. We demonstrate for the first time that colitis alters taste input to the brain, which could exacerbate malnutrition in IBD patients. [ABSTRACT FROM AUTHOR]

Taste bud cells are classified into four types by their ultrastructural features. Immunohistochemical detection of taste-signaling molecules is used to distinguish cell types of taste bud cells; however, the characteristics of taste cell types such as the immunoreactivity for taste-signaling molecules have long remained unclear. We investigated the detailed characteristics of taste cells in rat vallate taste buds by electron microscopy and immunohistochemistry for gustducin, neural cell adhesion molecule (NCAM) and vesicle-associated membrane protein 2 (VAMP2), which are known as markers of Type II cells, Type III cells and both cell types, respectively. Triple immunostaining for these molecules discriminated seven kinds of cell, including the totally immunopositive cell. Electron microscopy revealed Type III cells with a typical synaptic structure and subsurface cisterna as a specialized contact between a nerve and a Type II cell. The present study clarified the existence of cells with features of both Type II and Type III cells as a subtype of taste bud cells in the rat taste bud. [ABSTRACT FROM AUTHOR]

The current concept of taste transduction implicates the TASR/PLCβ2/IP3R3/TRPM5 axis in mediating chemo-electrical coupling in taste cells of the type II. While generation of IP3 has been verified as an obligatory step, DAG appears to be a byproduct of PIP2 cleavage by PLCβ2. Here, we provide evidence that DAG-signaling could play a significant and not yet recognized role in taste transduction. In particular, we found that DAG-gated channels are functional in type II cells but not in type I and type III cells. The DAG-gated current presumably constitutes a fraction of the generator current triggered by taste stimulation in type II cells. Bitter stimuli and DAG analogs produced Ca2+ transients in type II cells, which were greatly decreased at low bath Ca2+, indicating their dependence on Ca2+ influx. Among DAG-gated channels, transcripts solely for TRPC3 were detected in the taste tissue, thus implicating this channel in mediating DAG-regulated Ca2+ entry. Release of the afferent neurotransmitter ATP from CV papillae was monitored online by using the luciferin/luciferase method and Ussing-like chamber. It was shown that ATP secretion initiated by bitter stimuli and DAG analogs strongly depended on mucosal Ca2+. Based on the overall findings, we speculate that in taste transduction, IP3-driven Ca2+ release is transient and mainly responsible for rapid activation of Ca2+-gated TRPM5 channels, thus forming the initial phase of receptor potential. DAG-regulated Ca2+ entry through apically situated TRPC3 channels extends the primary Ca2+ signal and preserves TRPM5 activity, providing a needful prolongation of the receptor potential. [ABSTRACT FROM AUTHOR]

To reveal the specific differences in taste characteristics of Chinese rice wine, quantitative description analysis, temporal check-all-that-apply (TCATA), temporal dominance of sensation (TDS), time-intensity and an electronic tongue were used to evaluate taste attributes of different types of Chinese rice wine (YH, HD, SN and XX). First, it was found that sourness, sweetness, bitterness and umami endowed Chinese rice wine with unique taste characteristics, and brewing techniques had a significant effect on the taste characteristics of the four types of Chinese rice wine by quantitative description analysis. Then, TCATA test showed that the panelist citation proportion of the sour taste of YH was as high as 100% at the beginning of the evaluation. The citation proportion of the sour and bitter tastes of YH and HD showed a downward trend within 60s after drinking, meanwhile, that of the umami taste gradually increased after drinking for 30s. The sweet taste of SN and XX was stronger than YH and HD when was just drunk, and the citation proportion of the sweet and astringent tastes decreased with time. The TDS and time-intensity tests showed that the dominance of the sour taste of YH and HD continued to 15–20s, and the dominant rate of bitter taste at this stage showed an upward trend. The bitter taste of YH reached the highest dominance rate of 63.3% in 25s. The sweet dominance rate of XX at 0s reached 73.3%, and the dominant duration of sweet taste was close to 30s. And the bitterness of the four types of Chinese rice wine in each period exhibited the order of YH > HD > SN > XX. Finally, the response regularity of electronic tongue to each taste attribute of the four types of Chinese rice wine was consistent with the results of artificial sensory evaluation. A systematic taste evaluation method for Chinese rice wine combined with artificial sensory and intelligent sensory was established reliably. [ABSTRACT FROM AUTHOR]

Purpose: In a previous neuroimaging study, patients with taste loss showed stronger activations in gustatory cortices compared to people with normal taste function during taste stimulations. The aim of the current study was to examine whether there are changes in central-nervous functional connectivity in patients with taste loss. Methods: We selected 26 pairs of brain regions related to taste processing as our regions of interests (ROIs). Functional magnetic resonance imaging (fMRI) was used to measure brain responses in seven patients with taste loss and 12 healthy controls as they received taste stimulations (taste condition) and water (water condition). The data were analysed using ROI-to-ROI functional connectivity analysis (FCA). Results: We observed weaker functional connectivity in the patient group between the left and right orbitofrontal cortex in the taste condition and between the left frontal pole and the left superior frontal gyrus in the water condition. Conclusion: These results suggested that patients with taste loss experience changes of functional connectivity between brain regions not only relevant to taste processing but also to cognitive functions. While further studies are needed, fMRI might be helpful in diagnosing taste loss as an additional tool in exceptional cases. [ABSTRACT FROM AUTHOR]

Purpose: This study investigates the impact of etiology on the epidemiologic profile, disease severity, type of treatment and therapy outcome in smell and taste disorders. Methods: This is a retrospective analysis of 270 patients that presented with a smell or taste disorder in a specialized, tertiary care center. An established questionnaire was used to collect data from patients and physicians. Olfactometry was performed with the Sniffin' Sticks test kit, while gustometry was performed by taste strips. Results: Post-traumatic etiology was associated with young age (median 46 years) and male sex, and showed the most severe degrees of smell loss compared to other etiologies (64.3% anosmia). Postinfectious causes occurred more frequently in females (77.3%) and correlated with a history of pharyngeal surgery, suggesting a vulnerability for virally mediated sensory dysfunction following adenoid/tonsil removal. Parosmia also correlated with both postinfectious etiology (62.5%) and female sex. In sinunasal etiology, the presence of nasal polyps worsened the overall olfactory test score by approximately 50%. In particular, smell threshold and discrimination were reduced, while smell identification was not significantly impacted by nasal polyp obstruction. Sinunasal dysfunction was the only etiology to show significant improvement after therapy (73.9% improved). Finally, we could establish good correlations between the subjective impairment and objective dysfunction for each sensory modality. Conclusion: Each etiology of chemosensory dysfunction shows particular distributions of variables like sex, age, comorbidities and operations, disease severity, sensory threshold, discrimination and identification. This paper offers a detailed account of the correlations between the cause and the characteristics of smell and taste loss. [ABSTRACT FROM AUTHOR]

Heart diseases and related complications constitute a leading cause of death and socioeconomic threat worldwide. Despite intense efforts and research on the pathogenetic mechanisms of these diseases, the underlying cellular and molecular mechanisms are yet to be completely understood. Several lines of evidence indicate a critical role of inflammatory and oxidative stress responses in the development and progression of heart diseases. Nevertheless, the molecular machinery that drives cardiac inflammation and oxidative stress is not completely known. Recent data suggest an important role of cardiac bitter taste receptors (TAS2Rs) in the pathogenetic mechanism of heart diseases. Independent groups of researchers have demonstrated a central role of TAS2Rs in mediating inflammatory, oxidative stress responses, autophagy, impulse generation/propagation and contractile activities in the heart, suggesting that dysfunctional TAS2R signalling may predispose to cardiac inflammatory and oxidative stress disorders, characterised by contractile dysfunction and arrhythmia. Moreover, cardiac TAS2Rs act as gateway surveillance units that monitor and detect toxigenic or pathogenic molecules, including microbial components, and initiate responses that ultimately culminate in protection of the host against the aggression. Unfortunately, however, the molecular mechanisms that link TAS2R sensing of the cardiac milieu to inflammatory and oxidative stress responses are not clearly known. Therefore, we sought to review the possible role of TAS2R signalling in the pathophysiology of cardiac inflammation, oxidative stress, arrhythmia and contractile dysfunction in heart diseases. Potential therapeutic significance of targeting TAS2R or its downstream signalling molecules in cardiac inflammation, oxidative stress, arrhythmia and contractile dysfunction is also discussed. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this scoping review is to appraise the published literature on taste disturbance in patients with advanced cancer, with the specific objectives being to determine its prevalence, clinical features and complications. Methods: This scoping review was conducted using the recommended methodological framework. A detailed search of databases (Medline, Embase, CINAHL and PsycInfo) was conducted to identify eligible studies: eligible studies needed to include patients with advanced cancer and needed to include details of clinical features and/or complications of taste disturbance. Standard bibliographic/systematic review software was used to store the records and manage the review process, respectively. Results: Twenty-five studies were identified from the database searches. The studies identified included eight physical and/or psychological symptom studies, six symptom cluster studies, five oral symptom studies and six taste and/or smell specific studies. Detailed data is presented on the clinical features and complications of taste disturbance and on the symptom clusters involving taste disturbance in this cohort of patients. Conclusion: This scoping review identified a relatively small number of relevant studies involving a relatively small number of participants. Nevertheless, it confirms that taste disturbance is a common problem in patients with advanced cancer and is associated with significant morbidity because of the primary condition and the associated complications. [ABSTRACT FROM AUTHOR]

Purpose: Metallic taste (MT) is frequently observed during head and neck cancer treatments, but very little is known about its impact on nutritional status. The aim of this study was to explore the impact of MT on the quality of life and nutritional status in patients with head and neck cancer expressing MT. Methods: Questionnaires on quality of life, MT, weight, and food intake were filled out by 44 patients with head and neck cancer before, during, and up to 1 year after their treatment. Patients were divided into two groups based on their reported experience of MT. Results: MT was commonly observed (n = 12, 27.2%), always during the treatment phase, and mostly linked with radiotherapy or radiochemotherapy. Reported MT intensity was moderate (n = 6, 40%) to high (n = 4, 26.7%). MT had a significant negative impact on quality of life linked to dysgeusia (p = 0.025). The negative impacts of MT on food intake and on weight were not significant, possibly due to a combination of sample size, dropouts, and duration of observation. Further research in this area could provide additional insights into how to better address the issue related to MT and enhance the quality of care provided to this patient population. Conclusion: Metallic taste, experienced by 27.2% of the 44 patients with head and neck cancer, contributes to dysgeusia and results in a significant decline in quality of life associated with dysgeusia. Trial registration: ClinicalTrials.gov trial registration number: NCT03558789. [ABSTRACT FROM AUTHOR]

Previous experiments found that acceptance of saccharin by rats was reduced if they had prior experience of sucrose or some other highly palatable solution. This study tested whether such successive negative contrast (SNC) effects involve acquisition of an aversion to the new taste. In three experiments, rats were switched from sucrose exposure in Stage 1 to a less palatable solution containing a new taste in Stage 2. In Experiments 1 and 2, a novel flavor was added to a saccharin solution at the start of Stage 2. In Experiment 1, preference tests revealed a weak aversion to the added vanilla flavor in the Suc-Sacch group, while in Experiment 2 an aversion was found in the Suc-Sacch group to the salty flavor that was used, compared with controls given access either saccharin or water in Stage 1. In Experiment 3, the Suc-Quin group, given quinine solution in Stage 2, displayed a greater aversion to quinine than a Water-Quin control group. These results support the suggestion that taste aversion learning plays a role in the initial suppression of intakes in a qualitative consummatory SNC effect. However, in the light of other evidence, it seems that the unusual persistence of successive negative contrast when rats are switched from sucrose to saccharin is not due to a long-lasting reduction in the value of saccharin. [ABSTRACT FROM AUTHOR]

From the nutritional perspective, the main direction of the utilization of white mulberry (Morus alba L.) parts so far has been to produce dietary supplements or functional foods for individuals with diabetes or over-weight. Its leaves are widely known as a valuable source of bioactive compounds responsible for its antioxidant and antidiabetic effects, both in animals and humans. The authors found that processed leaves can also be investigated as potential bitter and/or sweet taste modulators—an important property of new functional foods. The study aimed to validate the inhibitory effect of Morus alba L. on the TAS2R3 and TAS2R13 bitter taste and TSA1R2/TSA1R3 receptors and determine the changes that the conditioning process caused in such receptors. The effect on the receptors was evaluated in specially transfected HEK293T cells, and the inhibition ratio was measured using the calcium release test. Moreover, the stability of phenolics in the simulated intestinal in vitro digestion process was determined. Results showed that the Morus alba leaf extracts were rich in gallic, chlorogenic and caffeic acids together with rutin and quercetin 3-(6-malonyl)-glucoside, while the conditioning process positively affected their amount. Most identified phenolics were reduced during in vitro digestion. In the taste receptors test, it was found that the phytochemicals from conditioned Morus alba leaf extract enhanced sweet taste, together with a reduction of bitter taste receptor activity in some cases. To conclude, the study has found that Morus alba, especially when conditioned for 4 h, seems to be a valuable modulator of taste, which should be considered in future research as a crucial reason for its new utilization. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to investigate whether caries-active and caries-free children differ in terms of their taste perception for sweet, sour, salty and bitter. Methods: The study group consisted of 100 children aged 5–10 years: 50 caries-free children and 50 children with at least four untreated carious lesions. Taste perception was analysed using two test systems. First, filter paper strips impregnated with four taste qualities (sweet, sour, salty, and bitter) at four defined intensities were used ("taste strips"). Then a tasting spray in suprathreshold concentration of the respective taste was applied. The children were asked to name the perceived taste. The parents answered a questionnaire about the children's dietary habits. Results: The children with high caries activity scored lower on average on the taste strips than the caries-free participants. For the taste sprays, the perception of the taste quality "bitter" was significantly worse in the children with caries than in caries-free children (Mann–Whitney U test p < 0.05). Conclusion: The results of this study suggest that taste preferences in children are associated with increased susceptibility to tooth decay. [ABSTRACT FROM AUTHOR]

Purpose: Cancer therapy is essential and lifesaving; however, it can have short- and long-term consequences on patients’ health. Up to 87% of cancer patients report changes in taste function, yet patients report a lack of support from clinicians regarding their experience with taste loss during and following treatment. Thus, the objective of this study was to assess clinicians’ knowledge and experience with managing patients with taste loss and identify potential gaps in the availability of educational materials and diagnostic tools. Method: In an online survey, sixty-seven participants who identify as clinicians and practice in the United States and work with cancer patients that complain of taste problems answered questions on their knowledge and experience supporting cancer patients experiencing changes in taste function and provided their opinion on access to educational materials. Results: The current study reports gaps in participants’ knowledge of taste and taste disorder terminology, with 15.4% correctly defining both taste and flavor and roughly half were familiar with specific taste disorder classifications. Over half of the participants reported not having access to adequate information to help their patients manage taste alterations. Only two-thirds of participants reported routinely asking patients if they are experiencing changes in taste function. Conclusion: Clinicians’ responses emphasized the need to improve access to educational materials regarding taste changes and increase the availability of information regarding management strategies. Addressing these inequities in education and improving the standard of care is the first step in improving the care for cancer patients suffering from altered taste function. [ABSTRACT FROM AUTHOR]

Purpose: This review aimed to evaluate the prevalence and characteristics of dysgeusia after hematopoietic cell transplantation (HCT). Methods: A literature search (in PubMed, Embase.com and Web of Science) for clinical studies evaluating taste before and after HCT was performed up to June 22, 2023, in collaboration with a medical information specialist. After title and abstract review (N = 807) followed by full-text review (N = 61), articles that met the inclusion criteria were summarized in a table and synthesized narratively. Results: 11 articles were analyzed in this review. All studies had a prospective design and patient populations included children (N = 3) and adults (N = 8) undergoing allogeneic or autologous HCT. Taste was assessed objectively (N = 6) and/or subjectively (N = 8) between baseline and 12 months after HCT. Before HCT, the self-reported (0–31%) and objective (2.4–10%) prevalence of dysgeusia was low. During the neutropenic phase, self-reported (20–100%) and objective (21.4%) dysgeusia was highest. In the post-engraftment period, the self-reported (18%) and objective (0–33%) prevalence of dysgeusia decreased. Different taste qualities were assessed in six studies including salt, sour, bitter, sweet, and umami. Conclusions: Some patients undergoing HCT experience dysgeusia prior to treatment. During the neutropenic phase, they had highest complaints, with recovery occurring in the post-engraftment period. All basic tastes, except bitter, were affected. Umami and salt were most affected during treatment. These findings have implications for patient management. [ABSTRACT FROM AUTHOR]