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The sweet taste of saccharides, such as sucrose and glucose, and other sweeteners is known to result from activation of the TAS1R2/R3 receptor expressed in taste receptor cells (TRCs) of the taste bud. Recent reports have suggested the existence of an additional sweet taste signaling pathway for metabolizable saccharides that is dependent on the activity of glucose transporters, especially SGLT1, also expressed in TRCs. We have investigated the potential contribution of SGLT1 to glucose taste signaling in humans. Concentration-response analysis of glucose mediated changes in membrane potential measured in Chinese hamster ovary (CHO) cells transiently expressing the human SGLT1 (hSGLT1) yielded an EC50 value of 452 μM. The SGLT inhibitor phlorizin inhibited the membrane potential response to 10 mM glucose with an IC50 of 3.5 μM. In contrast, EC50 values of 127 and 132 mM were obtained from concentration-response analysis of glucose taste in vehicles of water or 20 mM NaCl, respectively, by rapid throughput taste discrimination with human subjects. Lactisole, an antagonist of TAS1R2/R3, at a concentration of 1 mM completely inhibited taste responses to glucose concentrations of 250 mM and below. Phlorizin (0.2 mM) and the high potency SGLT1-selective inhibitor mizagliflozin (10 μM) failed to inhibit glucose taste detection measured at peri-threshold concentrations in the rapid throughput taste discrimination assay. A Yes/No experiment using the taste discrimination assay revealed that 0.2 mM phlorizin was discriminable from water for some subjects. Taken together the results indicate that agonist activation of TAS1R2/R3 is sufficient to account for all glucose taste without contribution by an alternative SGLT-mediated signaling pathway. Furthermore, the taste of phlorizin could be a confounding variable for studies evaluating a role for SGLTs in taste. [ABSTRACT FROM AUTHOR]

Peripheral taste neurons exhibit functional, genetic, and morphological diversity, yet understanding how or if these attributes combine into taste neuron types remains unclear. In this study, we used male and female mice to relate taste bud innervation patterns to the function of a subset of proenkephalin-expressing (Penk+) taste neurons. We found that taste arbors (the portion of the axon within the taste bud) stemming from Penk+ neurons displayed diverse branching patterns and lacked stereotypical endings. The range in complexity observed for individual taste arbors from Penk+ neuronsmirrored the entire population, suggesting that taste arbor morphologies are not primarily regulated by the neuron type. Notably, the distinguishing feature of arbors from Penk+ neurons was their propensity to come within 110 nm (in apposition with) different types of taste-transducing cells within the taste bud. This finding is contrary to the expectation of genetically defined taste neuron types that functionally represent a single stimulus. Consistently, further investigation of Penk+ neuron function revealed that they are more likely to respond to innately aversive stimuli--sour, bitter, and high salt concentrations-- as compared with the full taste population. Penk+ neurons are less likely to respond to nonaversive stimuli--sucrose, umami, and low salt--compared with the full population. Our data support the presence of a genetically defined neuron type in the geniculate ganglion that is responsive to innately aversive stimuli. This implies that genetic expression might categorize peripheral taste neurons into hedonic groups, rather than simply identifying neurons that respond to a single stimulus. [ABSTRACT FROM AUTHOR]

Background: The Japanese quail (Coturinx coturnix japonica) has a crucial role in the lives of humanity since the 12th century and continues to play main roles in our industry and scientific research. The advantages that the Japanese quail has, such as heavy egg production and high-quality meat with low cholesterol and fat contents, Moreover, the Japanese quail is easily managed, with high feeding conversion, low cost of investment, and high rate of returns. Salivary glands are a part of the lingual apparatus that secretes serios and mucous saliva. Whereas, the saliva secretions have different roles in the food variation, apprehension, and moisture of food bolus. The morphological and cytochemical analysis are done on 20 healthy Japanese quail embryos of 6th, 10th, 11th, and 13th days of incubation and 25 healthy quail chicks at hatching day old, 7th, 14th, 30th, and 60th days old. These samples are investigated histologically, histochemically, and scanned by electron microscopy serially. Our purpose of the study is to highlight the area of the oropharyngeal salivary glands and their role in food variation, as few studies spoke about that in Japanese quail. Results: The primordia of the sublingual and mandibular salivary glands were noticed at the 6th and 10th days of the prehatching respectively as an epithelial bud. After hatching, both primordia were elongated and differentiated into secretory units. These glands were mucous polystomatic tubulo-alveolar paired glands, which were situated in the submucosa of the oropharyngeal floor (sublingual floor and paralingual grooves). The sublingual glands consisted of 3–5 lobes extended from the two Os ceratobranchial by their wide ends caudally, to beyond the median sulcus of the prefrenular part of the sublingual space rostrally. The taste buds were variable in size and position. The mandibular glands lay on the paralingual groove, which arose at the 10-day old embryo. The mandibular glands were located dorsomedial to the sublingual glands and extended longitudinally from the rostral border of the frenulum linguae to the caudal tips of the sublingual glands. The taste buds decreased in volume and number with advancing age. Conclusion: Overall, salivary glands increase in their alcianophilic activity of the secretions with advancing age, which indicates low PH within the secretory end pieces. Highlights: • The oropharyngeal floor contains both the sublingual and mandibular salivary glands. • The sublingual and mandibular salivary glands were compound tubuloalveolar paired glands. • The sublingual salivary glands consist of non-branched 3–5 elongated lobes with common excretory duct. • The primordia of the sublingual salivary gland developed at 6 days old embryo as an epithelial bud. • The primordia of the mandibular salivary gland developed at 10 days old embryo. • Both glands' mucous secretion developmentally became with strong alcinophilic (acidic) contents. • The surface taste buds decreased in volume and number with age advancing. • Taste buds differed in size and position with taste pores from 8.2 to 12 μm. [ABSTRACT FROM AUTHOR]

The tongue serves as a vital organ in mammals, facilitating crucial functions such as mastication, swallowing, vocalization, thermoregulation, and taste reception. Cetacean tongues have evolved under distinct selective pressures compared to those of terrestrial mammals, yet research on their tongues is limited, leading to controversy regarding their gustatory abilities. This study aims to elucidate the morphological characteristics of the fetal tongue of common minke whales through both gross and microscopic observations. Macroscopic examination revealed that the papillae marginales were the only lingual papillae that were obviously developed in all specimens, and these projections are hypothesized to aid in suckling during the nursing period. Lingual glands were exclusively found in the proximal region of the tongue, unlike in toothed whales, where they are distributed in rostral regions. The rudimentary mechanical papillae and the caudal location of the lingual glands are thought to be consistent with the lunge feeding strategy. Neither macroscopic nor microscopic observations detected taste buds or any structures which are responsible for taste reception. Hence, it is suggested that gustation is not a crucial sense for nutrition in this species. These morphological findings enhance our understanding of rorqual feeding habits and provide insights for the management of this unique mammalian lineage. [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]

Background: Taste buds' innervation is necessary to sustain their cell turnover, differentiated taste buds and nerve fibers in circumvallate papilla (CVP) disappear following glossopharyngeal nerve transection. Normally, taste buds recover to baseline number in about 70 days. Bone marrow stem cell (BM-MSC) derived exosomes or their combination with Zinc chloride are used to assess their potential to speed up the regeneration process of CVP following bilateral deafferentation. Methods: Twenty-eight male Sprague-Dawley rats were randomly divided into four groups; Group I: subjected to sham operation followed by IP injection of saline. The other experimental groups (II, III and IV) were subjected to surgical bilateral transection of glossopharyngeal nerve. Group II received single IP injection of saline. Group III received single IV injection of BM-MSC-derived exosomes (100 µg). Group IV received single IV injection of BM-MSC-derived exosomes and single IP injection of zinc chloride (5 mg/kg). After 28 days, CVP was dissected and prepared for histological and histomorphometric analysis, RT-PCR for cytokeratin 8 gene expression, ELISA to assess protein level of brain-derived neurotrophic factor, redox state analysis of malondialdehyde and glutathione content, followed by statistical analysis. Results: Histopathologically, group II exhibited great tissue damage with marked reduction in taste buds and signs of degeneration in the remaining ones. Group III was close to control group with marked improvement in taste buds' number and structure. Group IV showed inferior results when compared to group III, with many immature taste buds and signs of degeneration. Statistical results showed that groups I and III have significantly higher values than groups II and IV regarding taste buds' number, cytokeratin 8, and reduced glutathione. However, malondialdehyde demonstrated high significant values in group IV compared to groups I and III. Regarding brain-derived neurotrophic factor, group III had significantly higher values than group II. Conclusion: BM-MSC-derived exosomes have superior regenerative potentials in acceleration of CVP and nerve healing following bilateral transection of glossopharyngeal nerve in contrary to its combination with zinc chloride. [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]

The gustatory system is responsible for detecting and evaluating the palatability of the various chemicals present in food and beverages. Taste bud cells, located primarily on the tongue, communicate with the gustatory sensory neurons by means of neurochemical signals, transmitting taste information to the brain. It has also been found that the endocannabinoid system (ECS) may modulate food intake and palatability, and that taste bud cells express cannabinoid receptors. The purpose of this study was to investigate the expression of cannabinoid and cannabinoid-related receptors in the gustatory cells of the papillae vallatae and foliatae of ten piglets. Specific antibodies against the cannabinoid receptors (CB1R and CB2R), G protein-coupled receptor 55 (GPR55), transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) were applied on cryosections of lingual tissue; the lingual tissue was also processed using Western blot analysis. Cannabinoid and cannabinoid-related receptors were found to be expressed in the taste bud cells and the surrounding epithelial cells. The extra-papillary epithelium also showed strong immunolabeling for these receptors. The results showed that these receptors were present in both the taste bud cells and the extra-gustatory epithelial cells, indicating their potential role in taste perception and chemesthesis. These findings contributed to understanding the complex interactions between cannabinoids and the gustatory system, highlighting the role of the ECS within taste perception and its potential use in animal production in order to enhance food intake. [ABSTRACT FROM AUTHOR]

Abstract Background Taste buds’ innervation is necessary to sustain their cell turnover, differentiated taste buds and nerve fibers in circumvallate papilla (CVP) disappear following glossopharyngeal nerve transection. Normally, taste buds recover to baseline number in about 70 days. Bone marrow stem cell (BM-MSC) derived exosomes or their combination with Zinc chloride are used to assess their potential to speed up the regeneration process of CVP following bilateral deafferentation. Methods Twenty-eight male Sprague-Dawley rats were randomly divided into four groups; Group I: subjected to sham operation followed by IP injection of saline. The other experimental groups (II, III and IV) were subjected to surgical bilateral transection of glossopharyngeal nerve. Group II received single IP injection of saline. Group III received single IV injection of BM-MSC-derived exosomes (100 µg). Group IV received single IV injection of BM-MSC-derived exosomes and single IP injection of zinc chloride (5 mg/kg). After 28 days, CVP was dissected and prepared for histological and histomorphometric analysis, RT-PCR for cytokeratin 8 gene expression, ELISA to assess protein level of brain-derived neurotrophic factor, redox state analysis of malondialdehyde and glutathione content, followed by statistical analysis. Results Histopathologically, group II exhibited great tissue damage with marked reduction in taste buds and signs of degeneration in the remaining ones. Group III was close to control group with marked improvement in taste buds’ number and structure. Group IV showed inferior results when compared to group III, with many immature taste buds and signs of degeneration. Statistical results showed that groups I and III have significantly higher values than groups II and IV regarding taste buds’ number, cytokeratin 8, and reduced glutathione. However, malondialdehyde demonstrated high significant values in group IV compared to groups I and III. Regarding brain-derived neurotrophic factor, group III had significantly higher values than group II. Conclusion BM-MSC-derived exosomes have superior regenerative potentials in acceleration of CVP and nerve healing following bilateral transection of glossopharyngeal nerve in contrary to its combination with zinc chloride. Graphical Abstract

Burning Mouth Syndrome (BMS) presents as a persistent, often perplexing pain condition characterised primarily by a sensation of burning, yet frequently lacks observable clinical evidence. The underlying mechanisms of BMS remain elusive. Typically, the tongue bears the brunt of the discomfort, followed by the inner lower lip and hard palate. Psychologically, BMS often intersects with anxiety and depression, forming common comorbidities. There's emerging research suggesting a potential link between Human Herpesvirus 6B (HHV-6B) and mental health disorders. This association raises the possibility of HHV-6B as a contributor to BMS. HHV-6B's hypothesised involvement in BMS could be from various avenues: direct damage to taste cells and nerves, eliciting an inflammatory response, or even disrupting olfactory functions. This narrative review aims to critically evaluate the current literature on the potential association between HHV-6B and BMS. It explores the role of HHV-6B in pain mechanisms, inflammatory responses, and its impact on sensory functions such as taste and olfaction, providing a comprehensive overview of its implications in BMS pathogenesis. [ABSTRACT FROM AUTHOR]

Introduction: We have recently demonstrated that Sox10-expressing (Sox10+) cells give rise to mainly type-III neuronal taste bud cells that are responsible for sour and salt taste. The two tissue compartments containing Sox10+ cells in the surrounding of taste buds include the connective tissue core of taste papillae and von Ebner's glands (vEGs) that are connected to the trench of circumvallate and foliate papillae. Methods: In this study, we performed single cell RNA-sequencing of the epithelium of Sox10-Cre/tdT mouse circumvallate/vEG complex and used inducible Cre mouse models to map the cell lineages of vEGs and/or connective tissue (including stromal and Schwann cells). Results: Transcriptomic analysis indicated that Sox10 expression was enriched in the cell clusters of vEG ducts that contained abundant proliferating cells, while Sox10-Cre/tdT expression was enriched in type-III taste bud cells and vEG ductal cells. In vivo lineage mapping showed that the traced cells were distributed in circumvallate taste buds concurrently with those in the vEGs, but not in the connective tissue. Moreover, multiple genes encoding pathogen receptors were enriched in the vEG ducts hosting Sox10+ cells. Discussion: Our data supports that it is the vEGs, not connective tissue core, that serve as the niche of Sox10+ taste bud progenitors. If this is also true in humans, our data indicates that vEG duct is a source of Sox10+ taste bud progenitors and susceptible to pathogen infections. [ABSTRACT FROM AUTHOR]

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Bitter taste receptors, also known as type 2 taste receptors (T2Rs), are found not only in the mouth's taste bud cells but also in various tissues and cells, including macrophages. Macrophages, known for their remarkable plasticity, play a crucial role in regulating innate immunity, managing inflammation, and orchestrating immune responses to antigens, pathogens, and environmental factors. Recently, the study of the expression and function of bitter taste receptors within macrophages has garnered significant interest. This review summarizes the expression levels and distribution characteristics of bitter taste receptors in macrophages and examines their effects on macrophage polarization, phagocytosis, and chemotaxis, as well as their potential molecular mechanisms. The purpose of this review is to provide insight and perspectives for research on the regulatory role of T2Rs in macrophage functions. [ABSTRACT FROM AUTHOR]

Since 2019, Coronavirus Disease 2019(COVID-19) has affected millions of people worldwide. Except for acute respiratory distress syndrome, dysgeusis is also a common symptom of COVID-19 that burdens patients for weeks or permanently. However, the mechanisms underlying taste dysfunctions remain unclear. Here, we performed complete autopsies of five patients who died of COVID-19. Integrated tongue samples, including numerous taste buds, salivary glands, vessels, and nerves were collected to map the pathology, distribution, cell tropism, and receptor distribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the tongue. Our results revealed that all patients had moderate lymphocyte infiltration around the salivary glands and in the lamina propria adjacent to the mucosa, and pyknosis in the epithelia of taste buds and salivary glands. This may be because the serous acini, salivary gland ducts, and taste buds are the primary sites of SARS-CoV-2 infection. Multicolor immunofluorescence showed that SARS-CoV-2 readily infects Keratin (KRT)7+ taste receptor cells in taste buds, secretory cells in serous acini, and inner epithelial cells in the ducts. The major receptors, angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine subtype 2 (TMPRSS2), were both abundantly expressed in these cells. Viral antigens and receptor were both rarely detected in vessels and nerves. This indicates that SARS-CoV-2 infection triggers pathological injury in the tongue, and that dysgeusis may be directly related to viral infection and cellular damage. [ABSTRACT FROM AUTHOR]

The ion channels Piezo 1 and Piezo 2 have been identified as membrane mechano-proteins. Studying mechanosensitive channels in chemosensory organs could help in understanding the mechanisms by which these channels operate, offering new therapeutic targets for various disorders. This study investigates the expression patterns of Piezo proteins in zebrafish chemosensory organs. For the first time, Piezo protein expression in adult zebrafish chemosensory organs is reported. In the olfactory epithelium, Piezo 1 immunolabels kappe neurons, microvillous cells, and crypt neurons, while Calretinin is expressed in ciliated sensory cells. The lack of overlap between Piezo 1 and Calretinin confirms Piezo 1's specificity for kappe neurons, microvillous cells, and crypt neurons. Piezo 2 shows intense immunoreactivity in kappe neurons, one-ciliated sensory cells, and multi-ciliated sensory cells, with overlapping Calretinin expression, indicating its olfactory neuron nature. In taste buds, Piezo 1 immunolabels Merkel-like cells at the bases of cutaneous and pharyngeal taste buds and the light and dark cells of cutaneous and oral taste buds. It also marks the dark cells of pharyngeal taste buds and support cells in oral taste buds. Piezo 2 is found in the light and dark cells of cutaneous and oral taste buds and isolated chemosensory cells. These findings provide new insights into the distribution of Piezo channels in zebrafish chemosensory organs, enhancing our understanding of their sensory processing and potential therapeutic applications. [ABSTRACT FROM AUTHOR]

It is widely believed that exposure to sweetened foods and beverages stimulates the liking and desire for sweetness. Here we provide an updated review of the empirical evidence from human research examining whether exposure to sweet foods or beverages influences subsequent general liking for sweetness ('sweet tooth'), based on the conclusions of existing systematic reviews and more recent research identified from a structured search of literature. Prior reviews have concluded that the evidence for a relationship between sweet taste exposure and measures of sweet taste liking is equivocal, and more recent primary research generally does not support the view that exposure drives increased liking for sweetness, in adults or children. In intervention trials using a range of designs, acute exposure to sweetness usually has the opposite effect (reducing subsequent liking and desire for sweet taste), while sustained exposures have no significant effects or inconsistent effects. Recent longitudinal observational studies in infants and children also report no significant associations between exposures to sweet foods and beverages with measures of sweet taste preferences. Overall, while it is widely assumed that exposure to sweetness stimulates a greater liking and desire for sweetness, this is not borne out by the balance of empirical evidence. While new research may provide a more robust evidence base, there are also a number of methodological, biological and behavioural considerations that may underpin the apparent absence of a positive relationship between sweetness exposure and liking. [ABSTRACT FROM AUTHOR]

The Hedgehog (HH) pathway regulates embryonic development of anterior tongue taste fungiform papilla (FP) and the posterior circumvallate (CVP) and foliate (FOP) taste papillae. HH signaling also mediates taste organ maintenance and regeneration in adults. However, there are knowledge gaps in HH pathway component expression during postnatal taste organ differentiation and maturation. Importantly, the HH transcriptional effectors GLI1, GLI2 and GLI3 have not been investigated in early postnatal stages; the HH receptors PTCH1, GAS1, CDON and HHIP, required to either drive HH pathway activation or antagonism, also remain unexplored. Using lacZ reporter mouse models, we mapped expression of the HH ligand SHH, HH receptors, and GLI transcription factors in FP, CVP and FOP in early and late postnatal and adult stages. In adults we also studied the soft palate, and the geniculate and trigeminal ganglia, which extend afferent fibers to the anterior tongue. Shh and Gas1 are the only components that were consistently expressed within taste buds of all three papillae and the soft palate. In the first postnatal week, we observed broad expression of HH signaling components in FP and adjacent, non-taste filiform (FILIF) papillae in epithelium or stroma and tongue muscles. Notably, we observed elimination of Gli1 in FILIF and Gas1 in muscles, and downregulation of Ptch1 in lingual epithelium and of Cdon, Gas1 and Hhip in stroma from late postnatal stages. Further, HH receptor expression patterns in CVP and FOP epithelium differed from anterior FP. Among all the components, only known positive regulators of HH signaling, SHH, Ptch1, Gli1 and Gli2, were expressed in the ganglia. Our studies emphasize differential regulation of HH signaling in distinct postnatal developmental periods and in anterior versus posterior taste organs, and lay the foundation for functional studies to understand the roles of numerous HH signaling components in postnatal tongue development. [ABSTRACT FROM AUTHOR]

Tuft cells are a group of rare epithelial cells that can detect pathogenic microbes and parasites. Many of these cells express signaling proteins initially found in taste buds. It is, however, not well understood how these taste signaling proteins contribute to the response to the invading pathogens or to the recovery of injured tissues. In this study, we conditionally nullified the signaling G protein subunit Gγ13 and found that the number of ectopic tuft cells in the injured lung was reduced following the infection of the influenza virus H1N1. Furthermore, the infected mutant mice exhibited significantly larger areas of lung injury, increased macrophage infiltration, severer pulmonary epithelial leakage, augmented pyroptosis and cell death, greater bodyweight loss, slower recovery, worsened fibrosis and increased fatality. Our data demonstrate that the Gγ13-mediated signal transduction pathway is critical to tuft cells-mediated inflammation resolution and functional repair of the damaged lungs.To our best knowledge, it is the first report indicating subtype-specific contributions of tuft cells to the resolution and recovery. [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]

Aims: Taste modifies eating behaviour, impacting body weight and potentially obesity development. The Obese Taste Bud (OTB) Study is a prospective cohort study launched in 2020 at the University of Leipzig Obesity Centre in cooperation with the HI‐MAG Institute. OTB will test the hypothesis that taste cell homeostasis and taste perception are linked to obesity. Here, we provide the study design, data collection process and baseline characteristics. Materials and Methods: Participants presenting overweight, obesity or normal weight undergo taste and smell tests, anthropometric, and taste bud density (TBD) assessment on Day 1. Information on physical and mental health, eating behaviour, physical activity, and dental hygiene are obtained, while biomaterial (saliva, tongue swap, blood) is collected in the fasted state. Further blood samples are taken during a glucose tolerance test. A stool sample is collected at home prior to Day 2, on which a taste bud biopsy follows dental examination. A subsample undergoes functional magnetic resonance imaging while exposed to eating‐related cognitive tasks. Follow‐up investigations after conventional weight loss interventions and bariatric surgery will be included. Results: Initial results show that glycated haemoglobin levels and age are negatively associated with TBD, while an unfavourable metabolic profile, current dieting, and vegan diet are related to taste perception. Olfactory function negatively correlates with age and high‐density lipoprotein cholesterol. Conclusion: Initial findings suggest that metabolic alterations are relevant for taste and smell function and TBD. By combining omics data from collected biomaterial with physiological, metabolic and psychological data related to taste perception and eating behaviour, the OTB study aims to strengthen our understanding of taste perception in obesity. [ABSTRACT FROM AUTHOR]

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 study aims to describe six subgemmal neurogenous plaque (SNP) cases and compile the previously available data on SNP. Searches on PubMed, Web of Science, Embase, Scopus, and a two-step study selection were performed to compile data from case reports/series of SNP published in English literature. Our six patients (range 29–63 years) had SNP in the posterior lateral border of the tongue. Four of them were associated with lymphoepithelial cysts. A total of 15 studies, comprising 116 patients, were included in this overview. There was a slight predilection for female patients (56.0%) in the 5th (22.4%) and the 7th (23.9%) decades. The lateral border of the tongue (66.4%) was the most common anatomical location. The major manifestation was nodule/papule. Histologically, the presence of taste buds (n = 40/ 34.5%), superficial neural plexus (n = 32/ 27.6%), deep nerve fascicles (n = 32/ 27.6%), ganglion cells (n = 41/ 35.3%), and lymphoid tissue (n = 22/ 19.0%) was mainly reported. Surgical removal was the primary approach, with a low recurrence rate. Although largely unknown, SNP is a regular and likely frequent structure located in the tongue. The findings emphasize the importance of describing clinicopathological patterns of SNP as a differential diagnosis of neural lesions that affect the tongue. [ABSTRACT FROM AUTHOR]

In nature, animals must navigate to forage according to their sensory inputs. Different species use different sensory modalities to locate food efficiently. For teleosts, food emits visual, mechanical, chemical, and/or possibly weak-electrical signals, which can be detected by optic, auditory/lateral line, and olfactory/taste buds sensory systems. However, how fish respond to and use different sensory inputs when locating food, as well as the evolution of these sensory modalities, remain unclear. We examined the Mexican tetra, Astyanax mexicanus, which is composed of two different morphs: a sighted riverine (surface fish) and a blind cave morph (cavefish). Compared with surface fish, cavefish have enhanced non-visual sensory systems, including the mechanosensory lateral line system, chemical sensors comprising the olfactory system and taste buds, and the auditory system to help navigate toward food sources. We tested how visual, chemical, and mechanical stimuli evoke food-seeking behavior. In contrast to our expectations, both surface fish and cavefish did not follow a gradient of chemical stimulus (food extract) but used it as a cue for the ambient existence of food. Surface fish followed visual cues (red plastic beads and food pellets), but, in the dark, were likely to rely on mechanosensors—the lateral line and/or tactile sensor—as cavefish did. Our results indicate cavefish used a similar sensory modality to surface fish in the dark, while affinity levels to stimuli were higher in cavefish. In addition, cavefish evolved an extended circling strategy to forage, which may yield a higher chance to capture food by swimming-by the food multiple times instead of once through zigzag motion. In summary, we propose that ancestors of cavefish, similar to the modern surface fish, evolved extended food-seeking behaviors, including circling motion, to adapt to the dark. [ABSTRACT FROM AUTHOR]

Taste is relevant because it has allowed us to discriminate between what is food and what is not, and even what can be toxic or dangerous when ingested. The search for new flavors is present in history of mankind. Since ancient times, the spices provided new taste experiences to make meals more palatable or as a means of preserving food; the search for spices was a motivation to make voyages that led to the discovery of new lands and continents. More recently, a viral pandemic that damages the olfaction and taste senses made us to remember the relevance of the senses. Small structures, called taste buds, located in the papillae of the tongue are responsible of the sense of taste. There are four types of taste buds that identify five tastes and one whose existence has not yet been fully proven. Taste alterations have different etiologies which will be commented on this review. [ABSTRACT FROM AUTHOR]

The everyday lives of late Ming and early Qing Jiangnan literati had interesting esthetic characteristics. This article analyzes drinking culture to explore these artistic lifestyles. The consumption of alcohol was not merely a way to satisfy the taste buds or the stomach. Rather, it was a form of entertainment and cultural practice that showcased lifestyle and personality. In addition to analyzing the emotional lives of Jiangnan literati, this article will also explore the esthetic concept of "leisure" (閒xian) as leisure embodied the esthetics of Jiangnan literati life. Leisure was a daily life pursuit of many Jiangnan literati, as well as a measure of a person's taste. The everyday lives of literati became more interesting and varied because they valued leisure. [ABSTRACT FROM AUTHOR]

IntroductionWe have recently demonstrated that Sox10-expressing (Sox10+) cells give rise to mainly type-III neuronal taste bud cells that are responsible for sour and salt taste. The two tissue compartments containing Sox10+ cells in the surrounding of taste buds include the connective tissue core of taste papillae and von Ebner’s glands (vEGs) that are connected to the trench of circumvallate and foliate papillae.MethodsIn this study, we performed single cell RNA-sequencing of the epithelium of Sox10-Cre/tdT mouse circumvallate/vEG complex and used inducible Cre mouse models to map the cell lineages of vEGs and/or connective tissue (including stromal and Schwann cells).ResultsTranscriptomic analysis indicated that Sox10 expression was enriched in the cell clusters of vEG ducts that contained abundant proliferating cells, while Sox10-Cre/tdT expression was enriched in type-III taste bud cells and vEG ductal cells. In vivo lineage mapping showed that the traced cells were distributed in circumvallate taste buds concurrently with those in the vEGs, but not in the connective tissue. Moreover, multiple genes encoding pathogen receptors were enriched in the vEG ducts hosting Sox10+ cells.DiscussionOur data supports that it is the vEGs, not connective tissue core, that serve as the niche of Sox10+ taste bud progenitors. If this is also true in humans, our data indicates that vEG duct is a source of Sox10+ taste bud progenitors and susceptible to pathogen infections.

Objective: Currently, electrocautery devices have frequently been used in penile surgical procedures. We hypothesized that electrocautery using during penile surgical procedures may harm the taste rosea and the dorsal nerve of the penis or clitoris. Methods: Eighteen young age male New Zealand rabbits were studied: five in the control (Group I, n=5), five in the penile surgery without using electrocautery (sham group, Group II, n=5), eight in the monopolar cautery (study group, Group III, n=8) groups under general anesthesia. The animals were followed for 3 weeks and sacrificed. Penile tissue—pudendal nerve root complexes and dorsal root ganglion of sacral 3 level were examined using stereological methods. The results were compared statistically. Results: The live and degenerated taste bud-like structures and degenerated neuron densities of pudendal ganglia (mean±standard deviation, n/mm3) were estimated as 198±24/mm3, 4±1/mm3, and 5±1/mm3 in Group I; 8±3/mm3, 174±21/mm3, and 24±7/mm3 in Group II; and 21±5/mm3, 137±14/mm3, and 95±12/mm3 in Group III, respectively. Neurodegeneration of taste buds and pudendal ganglia was significantly different between groups. Conclusion: Intact spinal cord and normal parasympathetic and thoracolumbar sympathetic networks are crucial for human sexual function. The present study indicates that the glans penis injury by using electrocautery may lead to pudendal ganglia degeneration. Iatrogenic damage to taste rosea and retrograde degeneration of the pudendal nerve may be the cause of sexual dysfunction responsible mechanism.

The poem "Dust of a Future " by Diane Leblanc is presented. First line: I used to curse small openings in a bag of sugar; Last Line: I cursed small openings in a bag of sugar.

Capsaicin is an active ingredient that characterizes the pungency of pepper, and is the key to the 'door of spicy sensation', that is, the source of spicy sensation. Through the interaction with the oral cavity, capsaicin substances make TRPV1 activated by capsaicin, increase intracellular calcium ions, trigger nerve endings, release neuropeptides, and finally cause the formation of pain sensation in the cerebral cortex, thus generating a spicy sensation. It has been found that capsaicin has certain damage to taste. Capsaicin may directly or indirectly inhibit the transmission of taste nerve by reducing the number of taste buds and changing the excitability of taste transduction or taste receptor cells, thus causing damage to relevant taste cells and nerves. This paper summarizes the regulation and damage mechanism of capsaicin to taste and the research status of the new capsaicin taste interaction technology, discusses the shortcomings of its potential influence mechanism, and looks forward to the future research direction, in order to provide reference for the application of capsaicin in food and the prevention of damage caused by capsaicin. [ABSTRACT FROM AUTHOR]

Introduction: In the first stage of the aquaculture program of a species, it is necessary to know the stages of its initial development. In artificial reproduction programs and after the fertilization stage, an important issue is the feeding of the larvae after the absorption of the yolk sac, because the greatest loss of fish occurs during the absorption of the yolk sac and the stage of transition from endogenous feeding to exogenous feeding. Also, it is very important to find out how to feed and the type of food ration in primary rearing. The feeding time also depends on the time of formation of sensory organs, sight, smell and taste. In this study, the development process of the taste organ in Persian sturgeon (Acipenser persicus) from the time of hatching to the 23rd DPH (day post hatch) was investigated. Materials and methods: After the artificial reproduction of the brooders, the larvae were sampled daily from the 1 to 9 DPH, and randomly in the 12th, 16th, 20th and 23 rd DPH to prepare SEM electron microscopy images. Results and discussion: In the 1 st DPH, the barbels were forming and a number of taste buds could be seen in the place where the mouth was formed. At the same time with the appearance of the lips and the growth and differentiation of the barbels, the taste buds developed. From the 5th DPH, the growth of taste buds increased and the number and size of these buds continued to be elevated in the lips, inside the mouth and barbels. From the 12th DPH, this increase dropped to some extent and happened only with the growth of the buds. From the 20th DPH onwards, it remained almost unchanged in terms of number and only the buds reached maturity. In addition, the number and density of taste buds in the upper lip was higher than the lower lip. The results of the maximum development process (5 th DPH-8 th DPH) of taste buds show the compatibility of the development of taste buds of the Persian sturgeon with the start of active feeding of this species (in the 8th DPH). Conclusion: In this research, the development process of the taste organ of Persian sturgeon from the time of hatching through the 23rd day was examined. Since knowledge of the early stages of the development in any fish species is one of the first requirements of any aquaculture program, the results of this study can help to optimize the breeding conditions of Persian sturgeon larvae during the early stages of development. [ABSTRACT FROM AUTHOR]

The red-eared slider (Trachemys scripta elegans) is renowned for its remarkable adaptations, yet much of its complex biology remains unknown. In this pioneering study, we utilized a combination of gross anatomy, scanning electron microscopy (SEM), light microscopy, and immunofluorescence techniques to examine the tongue's omnivorous adaptation in this species. This research bridges a critical knowledge gap, enhancing our understanding of this intriguing reptile. Gross examination revealed a unique arrowhead-shaped tongue with a median lingual fissure and puzzle-piece-shaped tongue papillae. SEM unveiled rectangular filiform, conical, and fungiform papillae, with taste pores predominantly on the dorsal surface and mucous cells on the lateral surface of the papillae. Histologically, the tongue's apex featured short rectangular filiform and fungiform papillae, while the body exhibited varying filiform shapes and multiple taste buds on fungiform papillae. The tongue's root contained lymphatic tissue with numerous lymphocytes surrounding the central crypt, alongside lingual skeletal musculature, blood and lymph vessels, and Raffin corpuscles in the submucosa. The lingual striated muscle bundles had different orientations, and the lingual hyaline cartilage displayed a bluish coloration of the ground substance, along with a characteristic isogenous group of chondrocytes. Our research represents the first comprehensive application of immunofluorescence techniques to investigate the cellular intricacies of the red-eared slider's tongue by employing seven distinct antibodies, revealing a wide array of compelling and significant findings. Vimentin revealed the presence of taste bud cells, while synaptophysin provided insights into taste bud and nerve bundle characteristics. CD34 and PDGFRα illuminated lingual stromal cells, and SOX9 and PDGFRα shed light on chondrocytes within the tongue's cartilage. CD20 mapped B-cell lymphocyte distribution in the lingual tonsil, while alpha smooth actin (α-SMA) exposed the intricate myofibroblast and smooth muscle network surrounding the lingual blood vessels and salivary glands. In conclusion, our comprehensive study advances our knowledge of the red-eared slider's tongue anatomy and physiology, addressing a significant research gap. These findings not only contribute to the field of turtle biology but also deepen our appreciation for the species' remarkable adaptations in their specific ecological niches. [ABSTRACT FROM AUTHOR]

OBJECTIVE Diagnosing equine grass sickness (EGS) requires histopathological evidence of chromatolysis and/or neuronal loss in peripheral autonomic ganglia. Previous investigators performed postmortem biopsies of gustatory papillae located on the tongue and found chromatolytic subgemmal neurons in all 13 EGS horses. The present study aimed to design a standardized lingual biopsy sampling method through a transbuccal approach in healthy standing horses and assess the quality of the obtained samples, to allow antemortem diagnosis of EGS in clinical cases. ANIMALS 6 healthy horses. METHODS A transbuccal approach was performed bilaterally in 6 healthy standing horses. After having reached a deep level of sedation, horses were placed in stocks and a Günther mouth gag was inserted. Local anesthesia followed by a vertical full thickness incision was performed on both cheeks. Foliate papillae biopsies were carried out using an arthroscopic rongeur inserted through each incision site under oral endoscopic control. Tongue movements were restricted with diazepam. Histological assessment of taste buds and subgemmal plexi neurons was performed using H&E-stained longitudinal sections. RESULTS The procedure was well tolerated in all horses. Minor complications observed were a transient facial paralysis, some incisional fluid collection, and abscesses. Ten samples (10/12) were suitable for assessment of neuronal perikarya. CLINICAL RELEVANCE This procedure was safe for subgemmal plexus biopsy in healthy standing horses. The obtained samples were adequate as long as they were neatly cut lengthwise for inclusion. The technique was also used for 2 clinical cases and revealed the complete absence of neuronal perikarya, confirming chronic EGS. [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]

Intermediate filaments constitute the most heterogeneous class among the major classes of cytoskeletal proteins of mammalian cells. The 40 or more intermediate filament proteins have been classified into five types which show very specific rules of expression in specialized cell types. This study aimed to investigate the immunohistochemical distribution of cytokeratins (CKs) 8, 18, and 19 as well as the intermediate filaments vimentin, laminin, and desmin in bovine and ovine tongues. Immunohistochemical staining was performed for CKs 8, 18, 19, vimentin, laminin, and desmin. Our results revealed similar immunostaining intensity and distribution among various CKs, contrasting with distinct patterns for vimentin, laminin, and desmin. Immunoreactions were primarily localized in serous acini and ductal epithelium for cytokeratins, while vimentin and laminin were evident in connective tissue, endothelium, serous acini, and desmin in striated and smooth muscles. This study highlighted the absence of CKs 8, 18, 19, vimentin, and desmin in the lingual epithelium of bovine and ovine tongues. These findings enabled the classification of epithelial cells based on their specific cytokeratin patterns. Furthermore, vimentin was identified in mesodermal tissues and organs, desmin in muscle tissue, and laminin played crucial roles in basement membrane formation, nerve tissue regeneration, innervation of epithelial taste buds, and tissue separation and connection. Our findings provide essential insights into intermediate filament dynamics at the cellular and tissue levels. They serve as a foundation for future studies using systematic molecular biological techniques in this field. [ABSTRACT FROM AUTHOR]

The evolutionary causes behind the development of taste discs (TDs), recognized as the only gustatory organs in metamorphosed Batrachia (Caudata and Anura), have yet to be determined. Taste buds (TBs) serve as the gustatory organs in aquatic batrachian larvae, as well as in both larval and adult caecilians (Gymnophiona) inhabiting either aquatic environments or moist terrestrial habitats. We describe the morphology of gustatory organs of adult crocodile newts (Tylototriton cf. verrucosus , Salamandridae, Caudata). Crocodile newts are semi-aquatic and exhibit increased specialization towards an aquatic feeding, distinguishing it from most members of the subfamily Pleurodelinae. Our findings confirm that TDs serve as the gustatory organs in adult T. cf. verrucosus , similarly to many batrachians. We also determined the density and sizes of TDs' sensory zones on the tongue and palate of T. cf. verrucosus , which differs from Batrachia. In terms of micro-morphology, two types of gustatory cells (GCs) were identified in the gustatory epithelium of T. cf. verrucosus. Our literature analysis suggests that TDs were larger in anurans compared to caudate amphibians, but were also larger in aquatic/semi-aquatic than in terrestrial anurans. [ABSTRACT FROM AUTHOR]

Abstract Background The starry puffer fish (Arothron stellatus, Anonymous, 1798) is a poisonous tetradontidae fish inhabiting the Red sea. The skin constitutes an important defense against any external effects. The study aims to characterize the dorso-ventral skin of the juvenile and the adult starry puffer fish using light and scanning electron microscopies. Twenty specimens of juvenile and adult fresh fishes were used. Results The scanning electron microarchitecture of the skin of the juvenile and adult fish showed delicate irregular-shaped protrusions, and well-defined bricks-like elevations on the dorsal side and interrupted folds as well as irregular-shaped protrusions on the ventral side. In adult fish, the patterned microridges of the superficial and deep epithelial cells (keratinocytes) were larger and well-defined in the dorsal skin than in the ventral side, the contrary was seen in the juvenile fish. The microridges were arranged in a fingerprint or honeycomb patterns. The openings of the mucous cells were more numerous in the dorsal skin in both age stages but more noticeable in adult. Furthermore, the sensory cells were more dominant in the juveniles than the adults. The odontic spines were only seen in adult. Histologically, few taste buds were observed in the epidermis of the dorsal skin surface of the adult fish. Both mucous and club cells were embedded in the epidermis of the juvenile and adult fish with different shapes and sizes. Melanophores were observed at the dorsal skin of both juvenile and adult fishes while fewer numbers were noticed at the ventral surfaces. Several dermal bony plates with different shapes and sizes were demonstrated in the skin of both adult and juvenile fishes. Conclusion The structural variations of skin of the juvenile and adult fishes may reflect the various environmental difficulties that they confront.