Drinking Non-nutritive Sweetness Solution of Sodium Saccharin or Rebaudioside a for Guinea Pigs: Influence on Histologic Change and Expression of Sweet Taste Receptors in Testis and Epididymis

Saccharin sodium and rebaudioside A are extensively used as non-nutritive sweeteners (NNSs) in daily life. NNSs elicit a multitude of endocrine influences on animals, differing across species and chemically distinct sweeteners, whose exposure induce activation of sweet taste receptors in oral and extra-oral tissues with consequences of metabolic changes. To evaluate the influence of NNSs on histologic change and expression of sweet taste receptors in testis and epididymis of young male guinea pigs, thirty 4-week-old male guinea pigs with body weight 245.73 ± 6.02 g were randomly divided into five groups (n = 6) and received normal water (control group) and equivalent sweetness low dose or high dose of sodium saccharin (L-SS, 1.5 mM or H-SS, 7.5 mM) or rebaudioside A (L-RA, 0.5 mM or H-RA, 2.5 mM) solution for 28 consecutive days. The results showed that the relative testis weight in male guinea pig with age of 56 days represented no significant difference among all groups; in spite of heavier body weight in L-SS and H-RA, NNS contributes no significant influence on serum testosterone and estradiol level. Low-dose 0.5 mM rebaudioside A enhanced testicular and epididymal functions by elevating the expressions of taste receptor 1 subunit 2 (T1R2) and gustducin α-subunit (GNAT3), and high-dose 7.5 mM sodium saccharin exerted adverse morphologic influences on testis and epididymis with no effect on the expression of T1R2, taste receptor 1 subunit 2 (T1R3), and GNAT3. In conclusion, these findings suggest that a high dose of sodium saccharin has potential adverse biologic effects on the testes and epididymis, while rebaudioside A is a potential steroidogenic sweetener for enhancing reproductive functions.

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Sweet Taste Receptor Signaling Network: Possible Implication for Cognitive Functioning

Neurology Research International ◽

10.1155/2015/606479 ◽

2015 ◽

Vol 2015 ◽

pp. 1-13 ◽

Cited By ~ 15

Author(s):

Menizibeya O. Welcome ◽

Nikos E. Mastorakis ◽

Vladimir A. Pereverzev

Keyword(s):

Cognitive Functioning ◽

Transmembrane Protein ◽

Taste Receptor ◽

Sweet Taste ◽

The Body ◽

Taste Receptors ◽

Receptor Signaling ◽

Sweet Taste Receptor ◽

Sweet Taste Receptors

Sweet taste receptors are transmembrane protein network specialized in the transmission of information from special “sweet” molecules into the intracellular domain. These receptors can sense the taste of a range of molecules and transmit the information downstream to several acceptors, modulate cell specific functions and metabolism, and mediate cell-to-cell coupling through paracrine mechanism. Recent reports indicate that sweet taste receptors are widely distributed in the body and serves specific function relative to their localization. Due to their pleiotropic signaling properties and multisubstrate ligand affinity, sweet taste receptors are able to cooperatively bind multiple substances and mediate signaling by other receptors. Based on increasing evidence about the role of these receptors in the initiation and control of absorption and metabolism, and the pivotal role of metabolic (glucose) regulation in the central nervous system functioning, we propose a possible implication of sweet taste receptor signaling in modulating cognitive functioning.

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Sweet-taste receptors, low-energy sweeteners, glucose absorption and insulin release

British Journal Of Nutrition ◽

10.1017/s0007114510002540 ◽

2010 ◽

Vol 104 (10) ◽

pp. 1415-1420 ◽

Cited By ~ 60

Author(s):

Andrew G. Renwick ◽

Samuel V. Molinary

Keyword(s):

Insulin Release ◽

Taste Receptor ◽

Sweet Taste ◽

Glucose Absorption ◽

Enteroendocrine Cells ◽

Low Energy ◽

Taste Receptors ◽

Sweet Taste Receptors

The present review explores the interactions between sweeteners and enteroendocrine cells, and consequences for glucose absorption and insulin release. A combination of in vitro,in situ, molecular biology and clinical studies has formed the basis of our knowledge about the taste receptor proteins in the glucose-sensing enteroendocrine cells and the secretion of incretins by these cells. Low-energy (intense) sweeteners have been used as tools to define the role of intestinal sweet-taste receptors in glucose absorption. Recent studies using animal and human cell lines and knockout mice have shown that low-energy sweeteners can stimulate intestinal enteroendocrine cells to release glucagon-like peptide-1 and glucose-dependent insulinotropic peptide. These studies have given rise to major speculations that the ingestion of food and beverages containing low-energy sweeteners may act via these intestinal mechanisms to increase obesity and the metabolic syndrome due to a loss of equilibrium between taste receptor activation, nutrient assimilation and appetite. However, data from numerous publications on the effects of low-energy sweeteners on appetite, insulin and glucose levels, food intake and body weight have shown that there is no consistent evidence that low-energy sweeteners increase appetite or subsequent food intake, cause insulin release or affect blood pressure in normal subjects. Thus, the data from extensive in vivo studies in human subjects show that low-energy sweeteners do not have any of the adverse effects predicted by in vitro,in situ or knockout studies in animals.

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Drosophila sweet taste receptor

Pure and Applied Chemistry ◽

10.1351/pac200274071159 ◽

2002 ◽

Vol 74 (7) ◽

pp. 1159-1165 ◽

Cited By ~ 3

Author(s):

Kunio Isono ◽

Kohei Ueno ◽

Masayuki Ohta ◽

Hiromi Morita

Keyword(s):

Taste Receptor ◽

Sweet Taste ◽

P Element ◽

Taste Receptors ◽

Wild Populations ◽

Intracellular Loop ◽

Sweet Taste Receptor ◽

Loop Domain ◽

Sweet Taste Receptors ◽

Receptor Family

Like the Sac locus controlling sugar sensitivity in mice, the taste gene Tre of the fruitfly Drosophila was discovered in wild populations as a genetic dimorphism controlling gustatory sensitivity to a sugar trehalose. By activating a P-element transposon near the gene locus we obtained induced Tre mutations and analyzed the associated changes in gene organizations and the mRNA expressions. The analysis showed that Tre is identical to Gr5a, a gene that belongs to a novel seven-transmembrane receptor family expressed in chemosensory neurons and predicted to encode chemosensory receptors. Thus, Gr5a is a candidate sweet taste receptor in the fly. An amino acid substitution in the second intracellular loop domain was identified to be functionally correlated with the genetic dimorphism of Tre. Since Tre controls sweet taste sensitivity to a limited subset of sugars, other Gr genes phylogenetically related to Tre may also encode sweet taste receptors. Those candidate sweet taste receptors, however, are phylogenetically distinct from vertebrate sweet taste receptors, suggesting that the sweet taste receptors in animals do not share a common origin.

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Contribution of the T1r3 Taste Receptor to the Response Properties of Central Gustatory Neurons

Journal of Neurophysiology ◽

10.1152/jn.90892.2008 ◽

2009 ◽

Vol 101 (5) ◽

pp. 2459-2471 ◽

Cited By ~ 29

Author(s):

Christian H. Lemon ◽

Robert F. Margolskee

Keyword(s):

Normal Development ◽

Nucleus Tractus Solitarius ◽

Monosodium Glutamate ◽

Taste Receptor ◽

Residual Activity ◽

Sweet Taste ◽

Taste Receptors ◽

Wild Type ◽

Sweet Taste Receptors ◽

Gustatory Neurons

T1r3 is a critical subunit of T1r sweet taste receptors. Here we studied how the absence of T1r3 impacts responses to sweet stimuli by taste neurons in the nucleus tractus solitarius (NTS) of the mouse. The consequences bear on the multiplicity of sweet taste receptors and how T1r3 influences the distribution of central gustatory neurons. Taste responses to glycine, sucrose, NaCl, HCl, and quinine were electrophysiologically recorded from single NTS neurons in anesthetized T1r3 knockout (KO) and wild-type (WT) C57BL/6 mice. Other stimuli included l-proline, d-fructose, d-glucose, d-sorbitol, Na-saccharin, acesulfame-K, monosodium glutamate, NaNO3, Na-acetate, citric acid, KCl, denatonium, and papaverine. Forty-one WT and 41 KO neurons were recorded. Relative to WT, KO responses to all sweet stimuli were significantly lower, although the degree of attenuation differed among stimuli, with near zero responses to sugars but salient residual activity to artificial sweeteners and glycine. Residual KO across-neuron responses to sweet stimuli were variably similar to nonsweet responses, as indexed by multivariate and correlation analyses. In some cases, this suggested that residual KO activity to “sweet” stimuli could be mediated by nonsweet taste receptors, implicating T1r3 receptors as primary contributors to NTS sweet processing. The influence of T1r3 on the distribution of NTS neurons was evaluated by comparing neuron types that emerged between WT and KO cells. Neurons tuned toward sweet stimuli composed 34% of the WT sample but did not appear among KO cells. Input from T1r3-containing receptors critically guides the normal development of NTS neurons oriented toward sweet tastants.

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Taste sensations: history of study, evolutionary feasibility and strategies for forming correct taste preferences in children

Medical Council ◽

10.21518/2079-701x-2020-10-65-73 ◽

2020 ◽

pp. 65-73

Author(s):

I. N. Zakharova ◽

Yu. A. Dmitrieva ◽

E. B. Machneva ◽

A. N. Tsutsaeva

Keyword(s):

Eating Disorders ◽

Human Health ◽

Taste Receptor ◽

Sweet Taste ◽

Food Selectivity ◽

Taste Preferences ◽

Taste Receptors ◽

Sweet Taste Receptor ◽

Sweet Taste Receptors ◽

History Of

Taste preferences influence not only the formation of human health, but also many areas of his life. That is why the problem of understanding the nature and regularities of taste formation has been a concern for scientists since ancient times and remains relevant nowadays. The article presents generalized data on the history of studying taste from the times of Ancient Greece to our time. Notions about the system of taste sensations in works of Aristotle, Galen, Avicenna, Vesaliy, other medieval scientists and researchers of New time are described. The authors also present an overview of current studies on the evolutionary appropriateness of taste sensations using the expression of sweet taste receptors in animals with different diets. It has been shown that obligate carnivorous animals have lost the function of sweet taste receptors, and in hummingbirds eating sweet floral nectar, on the contrary, another sweet taste receptor has acquired the function of a sweet taste receptor to detect sugars. The authors pay special attention to the available ways of forming correct taste preferences and overcoming eating disorders in infants, which is important from the point of view of the child’s future health. In particular, strategies for repeated taste effects of new foods as well as multisensory interactions with food, including sound, visual, olfactory, tactile and tasting effects are presented. It is particularly important to develop correct taste habits in children with eating disorders such as neophobia and food selectivity. Understanding the multifactorial nature of taste preferences and their impact on human health allows finding new strategies to «teach» taste from early childhood.

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Loss of sweet taste despite the conservation of sweet receptor genes in insectivorous bats

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2021516118 ◽

2021 ◽

Vol 118 (4) ◽

pp. e2021516118

Author(s):

Hengwu Jiao ◽

Huan-Wang Xie ◽

Libiao Zhang ◽

Nima Zhuoma ◽

Peihua Jiang ◽

...

Keyword(s):

Functional Divergence ◽

Receptor Gene ◽

Taste Receptor ◽

Sweet Taste ◽

Taste Perception ◽

Taste Receptors ◽

Behavioral Experiments ◽

Insectivorous Bats ◽

Sweet Taste Receptor ◽

Sweet Taste Receptors

The evolution of taste perception is usually associated with the ecology and dietary changes of organisms. However, the association between feeding ecology and taste receptor evolution is unclear in some lineages of vertebrate animals. One example is the sweet taste receptor gene Tas1r2. Previous analysis of partial sequences has revealed that Tas1r2 has undergone equally strong purifying selection between insectivorous and frugivorous bats. To test whether the sweet taste function is also important in bats with contrasting diets, we examined the complete coding sequences of both sweet taste receptor genes (Tas1r2 and Tas1r3) in 34 representative bat species. Although these two genes are highly conserved between frugivorous and insectivorous bats at the sequence level, our behavioral experiments revealed that an insectivorous bat (Myotis ricketti) showed no preference for natural sugars, whereas the frugivorous species (Rousettus leschenaultii) showed strong preferences for sucrose and fructose. Furthermore, while both sweet taste receptor genes are expressed in the taste tissue of insectivorous and frugivorous bats, our cell-based assays revealed striking functional divergence: the sweet taste receptors of frugivorous bats are able to respond to natural sugars whereas those of insectivorous bats are not, which is consistent with the behavioral preference tests, suggesting that functional evolution of sweet taste receptors is closely related to diet. This comprehensive study suggests that using sequence conservation alone could be misleading in inferring protein and physiological function and highlights the power of combining behavioral experiments, expression analysis, and functional assays in molecular evolutionary studies.

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Whole-Brain Mapping of the Expression Pattern of T1R2, a Subunit Specific to the Sweet Taste Receptor

Frontiers in Neuroanatomy ◽

10.3389/fnana.2021.751839 ◽

2021 ◽

Vol 15 ◽

Author(s):

Jea Hwa Jang ◽

Ha Kyeong Kim ◽

Dong Woo Seo ◽

Su Young Ki ◽

Soonhong Park ◽

...

Keyword(s):

Central Nervous System ◽

Metabolic Regulation ◽

Taste Receptor ◽

Sweet Taste ◽

Taste Receptors ◽

Sweet Taste Receptor ◽

Sweet Taste Receptors ◽

The Central Nervous System ◽

A Subunit ◽

The Brain

Chemosensory receptors are expressed primarily in sensory organs, but their expression elsewhere can permit ligand detection in other contexts that contribute to survival. The ability of sweet taste receptors to detect natural sugars, sugar alcohols, and artificial sweeteners suggests sweet taste receptors are involved in metabolic regulation in both peripheral organs and in the central nervous system. Our limited knowledge of sweet taste receptor expression in the brain, however, has made it difficult to assess their contribution to metabolic regulation. We, therefore, decided to profile the expression pattern of T1R2, a subunit specific to the sweet taste receptor complex, at the whole-brain level. Using T1r2-Cre knock-in mice, we visualized the overall distribution of Cre-labeled cells in the brain. T1r2-Cre is expressed not only in various populations of neurons, but also in glial populations in the circumventricular organs and in vascular structures in the cortex, thalamus, and striatum. Using immunohistochemistry, we found that T1r2 is expressed in hypothalamic neurons expressing neuropeptide Y and proopiomelanocortin in arcuate nucleus. It is also co-expressed with a canonical taste signaling molecule in perivascular cells of the median eminence. Our findings indicate that sweet taste receptors have unidentified functions in the brain and suggest that they may be a novel therapeutic target in the central nervous system.

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