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Iyer S, Montmayeur JP, Zolotukhin S, Dotson CD. Exogenous oral application of PYY and exendin-4 impacts upon taste-related behavior and taste perception in wild-type mice. Neuropharmacology 2025; 272:110408. [PMID: 40086622 PMCID: PMC12042652 DOI: 10.1016/j.neuropharm.2025.110408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2024] [Revised: 02/26/2025] [Accepted: 03/09/2025] [Indexed: 03/16/2025]
Abstract
Several gut peptides have been implicated in feeding and body mass accumulation. Glucagon-like peptide 1 (GLP-1) and peptide tyrosine-tyrosine (PYY) have been shown to mediate satiety and reduce food intake. While systemic administration of such peptides has been explored as a therapy for metabolic disease, the effects of these hormones on taste signaling should also be considered given the importance of taste to feeding decisions and considering the fact that components of these signaling systems are expressed in cells of the peripheral gustatory system. We previously demonstrated that genetic disruption of PYY signaling in mice can impact on taste responsiveness and feeding and that viral expression of PYY in the salivary glands of PYY knockout mice can rescue responsiveness. The present work uses adeno-associated virus-mediated salivary gland treatment with both GLP-1 receptor agonist exendin-4 and/or PYY encoding vectors to explore the effect of stimulating these orally present signaling systems on taste-related behavioral responsiveness in male wild-type mice with intact peptide signaling systems. Results showed a significant effect of salivary gland treatment on responsiveness to multiple taste qualities. Data gathered from taste bud cells in vitro suggest that these peptides directly influence the responsiveness of these primary sensory cells. Collectively, these findings show that taste perception can be modulated by the exogenous application of satiety peptides in wild-type mice and suggest that the taste bud is a promising substrate for food intake modulation.
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Affiliation(s)
- Satya Iyer
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA
| | | | - Sergei Zolotukhin
- Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, 32610, USA
| | - Cedrick D Dotson
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA.
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2
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Odegaard KE, Bouaichi CG, Owanga G, Vincis R. Neural Processing of Taste-Related Signals in the Mediodorsal Thalamus of Mice. J Neurosci 2025; 45:e1500242025. [PMID: 40139805 PMCID: PMC12044043 DOI: 10.1523/jneurosci.1500-24.2025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2024] [Revised: 03/11/2025] [Accepted: 03/18/2025] [Indexed: 03/29/2025] Open
Abstract
Our consummatory decisions depend on the taste of food and the reward experienced while eating, which are processed through neural computations in interconnected brain areas. Although many gustatory regions of rodents have been explored, the mediodorsal nucleus of the thalamus (MD) remains understudied. The MD, a multimodal brain area connected with gustatory centers, is often studied for its role in processing associative and cognitive information and has been shown to represent intraorally delivered chemosensory stimuli after strong retronasal odor-taste associations. Key questions remain about whether MD neurons can process taste quality independently of odor-taste associations and how they represent extraoral signals predicting rewarding and aversive gustatory outcomes. Here, using C57 male and female mice we present electrophysiological evidence demonstrating how MD neurons represent and encode 1) the identity and concentrations of basic taste qualities during active licking, and 2) auditory signals anticipating rewarding and aversive taste outcomes. Our data reveal that MD neurons can reliably and dynamically encode taste identity in a broadly tuned manner and taste concentrations with spiking activity positively and negatively correlated with stimulus intensity. Our data also show that MD can represent information related to predictive cues and their associated outcomes, regardless of whether the cue predicts a rewarding or aversive outcome. In summary, our findings suggest that the mediodorsal thalamus is integral to the taste pathway, as it can encode sensory-discriminative dimensions of tastants and participate in processing associative information essential for ingestive behaviors.Significance Statement Dietary decisions are driven by the taste of the food and the reward experienced while eating. This information is processed through neural computations across interconnected brain areas. Given its neural connections, the mediodorsal thalamus (MD) could be part of this network. However, its involvement in gustatory processing is largely ignored. This study examines how MD neurons respond to taste quality, intensity, and expectation by analyzing the electrical activity of MD neurons in mice allowed to freely lick a spout to obtain different tastes. Our findings support the idea that the MD is part of the brain network responsible for processing sensory and associative information relevant to eating.
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Affiliation(s)
- Katherine E. Odegaard
- Department of Biological Science and Program in Neuroscience, Florida State University, Tallahassee, Florida 32306
| | - Cecilia G. Bouaichi
- Department of Biological Science and Program in Neuroscience, Florida State University, Tallahassee, Florida 32306
| | - Greg Owanga
- Department of Mathematics, Florida State University, Tallahassee, Florida 32306
| | - Roberto Vincis
- Department of Biological Science, Programs in Neuroscience, Molecular Biophysics and Cell and Molecular Biology, Florida State University, Tallahassee, Florida 32306
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3
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Odegaard KE, Bouaichi CG, Owanga G, Vincis R. Neural Processing of Taste-Related Signals in the Mediodorsal Thalamus of Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2025:2024.08.05.606609. [PMID: 39149395 PMCID: PMC11326204 DOI: 10.1101/2024.08.05.606609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Our consummatory decisions depend on the taste of food and the reward experienced while eating, which are processed through neural computations in interconnected brain areas. Although many gustatory regions of rodents have been explored, the mediodorsal nucleus of the thalamus (MD) remains understudied. The MD, a multimodal brain area connected with gustatory centers, is often studied for its role in processing associative and cognitive information and has been shown to represent intraorally-delivered chemosensory stimuli after strong retronasal odor-taste associations. Key questions remain about whether MD neurons can process taste quality independently of odor-taste associations and how they represent extraoral signals predicting rewarding and aversive gustatory outcomes. Here, using C57 male and female mice we present electrophysiological evidence demonstrating how MD neurons represent and encode 1) the identity and concentrations of basic taste qualities during active licking, and 2) auditory signals anticipating rewarding and aversive taste outcomes. Our data reveal that MD neurons can reliably and dynamically encode taste identity in a broadly tuned manner and taste concentrations with spiking activity positively and negatively correlated with stimulus intensity. Our data also show that MD can represent information related to predictive cues and their associated outcomes, regardless of whether the cue predicts a rewarding or aversive outcome. In summary, our findings suggest that the mediodorsal thalamus is integral to the taste pathway, as it can encode sensory-discriminative dimensions of tastants and participate in processing associative information essential for ingestive behaviors.
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Affiliation(s)
- Katherine E. Odegaard
- Florida State University, Department of Biological Science and Program in Neuroscience
| | - Cecilia G. Bouaichi
- Florida State University, Department of Biological Science and Program in Neuroscience
| | - Greg Owanga
- Florida State University, Department of Mathematics
| | - Roberto Vincis
- Florida State University, Department of Biological Science, Programs in Neuroscience, Molecular Biophysics and Cell and Molecular Biology
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4
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Yoshida R, Ninomiya Y. Mechanisms and Functions of Sweet Reception in Oral and Extraoral Organs. Int J Mol Sci 2024; 25:7398. [PMID: 39000505 PMCID: PMC11242429 DOI: 10.3390/ijms25137398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 06/27/2024] [Accepted: 07/03/2024] [Indexed: 07/16/2024] Open
Abstract
The oral detection of sugars relies on two types of receptor systems. The first is the G-protein-coupled receptor TAS1R2/TAS1R3. When activated, this receptor triggers a downstream signaling cascade involving gustducin, phospholipase Cβ2 (PLCβ2), and transient receptor potential channel M5 (TRPM5). The second type of receptor is the glucose transporter. When glucose enters the cell via this transporter, it is metabolized to produce ATP. This ATP inhibits the opening of KATP channels, leading to cell depolarization. Beside these receptor systems, sweet-sensitive taste cells have mechanisms to regulate their sensitivity to sweet substances based on internal and external states of the body. Sweet taste receptors are not limited to the oral cavity; they are also present in extraoral organs such as the gastrointestinal tract, pancreas, and brain. These extraoral sweet receptors are involved in various functions, including glucose absorption, insulin release, sugar preference, and food intake, contributing to the maintenance of energy homeostasis. Additionally, sweet receptors may have unique roles in certain organs like the trachea and bone. This review summarizes past and recent studies on sweet receptor systems, exploring the molecular mechanisms and physiological functions of sweet (sugar) detection in both oral and extraoral organs.
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Affiliation(s)
- Ryusuke Yoshida
- Department of Oral Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
- Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan
| | - Yuzo Ninomiya
- Department of Oral Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
- Graduate School of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
- Monell Chemical Senses Center, Philadelphia, PA 19104, USA
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Hamel EA, Blonde GD, Girish R, Krubitski B, Spector AC. Addition of low sodium does not increase sensitivity to glucose in wild-type mice, or lead to partial glucose taste detection in T1R3 knock-out mice. Physiol Behav 2024; 279:114544. [PMID: 38574794 PMCID: PMC12007246 DOI: 10.1016/j.physbeh.2024.114544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/30/2024] [Accepted: 04/01/2024] [Indexed: 04/06/2024]
Abstract
The sodium glucose cotransporter 1 (SGLT1) has been proposed as a non-T1R glucosensor contributing to glucose taste. Studies have shown that the addition of NaCl at very weak concentrations to a glucose stimulus can enhance signaling in the gustatory nerves of mice and significantly lower glucose detection thresholds in humans. Here, we trained mice with (wild-type; WT) and without (knockout; KO) a functioning T1R3 subunit on a two-response operant detection task to differentially respond to the presence or absence of a taste stimulus immediately after sampling. After extensive training (∼40 sessions), KO mice were unable to reliably discriminate 2 M glucose+0.01 M NaCl from 0.01 M NaCl alone, but all WT mice could. We then tested WT mice on a descending array of glucose concentrations (2.0-0.03 M) with the addition of 0.01 M NaCl vs. 0.01 M NaCl alone. The concentration series was then repeated with glucose alone vs. water. We found no psychophysical evidence of a non-T1R taste transduction pathway involved in the detection of glucose. The addition of NaCl to glucose did not lower taste detection thresholds in WT mice, nor did it render the stimulus detectable to KO mice, even at 2 M. The proposed pathway must contribute to functions other than sensory-discriminative detection, at least when tested under these conditions. Detection thresholds were also derived for fructose and found to be 1/3 log10 lower than for glucose, but highly correlated (r = 0.88) between the two sugars, suggesting that sensitivity to these stimuli in this task was based on a similar neural process.
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Affiliation(s)
- Elizabeth A Hamel
- Department of Psychology and Program in Neuroscience, Florida State University, 1107 W Call St, Tallahassee, FL 32306, United States
| | - Ginger D Blonde
- Department of Psychology and Program in Neuroscience, Florida State University, 1107 W Call St, Tallahassee, FL 32306, United States
| | - Riya Girish
- Department of Psychology and Program in Neuroscience, Florida State University, 1107 W Call St, Tallahassee, FL 32306, United States
| | - Belle Krubitski
- Department of Psychology and Program in Neuroscience, Florida State University, 1107 W Call St, Tallahassee, FL 32306, United States
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, 1107 W Call St, Tallahassee, FL 32306, United States.
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Ascencio Gutierrez V, Martin LE, Simental-Ramos A, James KF, Medler KF, Schier LA, Torregrossa AM. TRPM4 and PLCβ3 contribute to normal behavioral responses to an array of sweeteners and carbohydrates but PLCβ3 is not needed for taste-driven licking for glucose. Chem Senses 2024; 49:bjae001. [PMID: 38183495 PMCID: PMC10825839 DOI: 10.1093/chemse/bjae001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Indexed: 01/08/2024] Open
Abstract
The peripheral taste system is more complex than previously thought. The novel taste-signaling proteins TRPM4 and PLCβ3 appear to function in normal taste responding as part of Type II taste cell signaling or as part of a broadly responsive (BR) taste cell that can respond to some or all classes of tastants. This work begins to disentangle the roles of intracellular components found in Type II taste cells (TRPM5, TRPM4, and IP3R3) or the BR taste cells (PLCβ3 and TRPM4) in driving behavioral responses to various saccharides and other sweeteners in brief-access taste tests. We found that TRPM4, TRPM5, TRPM4/5, and IP3R3 knockout (KO) mice show blunted or abolished responding to all stimuli compared with wild-type. IP3R3 KO mice did, however, lick more for glucose than fructose following extensive experience with the 2 sugars. PLCβ3 KO mice were largely unresponsive to all stimuli except they showed normal concentration-dependent responding to glucose. The results show that key intracellular signaling proteins associated with Type II and BR taste cells are mutually required for taste-driven responses to a wide range of sweet and carbohydrate stimuli, except glucose. This confirms and extends a previous finding demonstrating that Type II and BR cells are both necessary for taste-driven licking to sucrose. Glucose appears to engage unique intracellular taste-signaling mechanisms, which remain to be fully elucidated.
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Affiliation(s)
| | - Laura E Martin
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, United States
| | - Aracely Simental-Ramos
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, United States
| | - Kimberly F James
- Department of Psychology, State University of New York at Buffalo, Buffalo, NY 14260, United States
| | - Kathryn F Medler
- Department of Cell and Molecular Biology, Virginia Tech, Blacksburg, VA 24061, United States
| | - Lindsey A Schier
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, United States
| | - Ann-Marie Torregrossa
- Department of Psychology, State University of New York at Buffalo, Buffalo, NY 14260, United States
- University at Buffalo Center for Ingestive Behavior Research, Buffalo, NY 14260, United States
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Pullicin AJ, Wils D, Lim J. Oral glucose sensing in cephalic phase insulin release. Appetite 2023; 191:107070. [PMID: 37788735 DOI: 10.1016/j.appet.2023.107070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 09/07/2023] [Accepted: 09/30/2023] [Indexed: 10/05/2023]
Abstract
Oral stimulation with foods or food components elicits cephalic phase insulin release (CPIR), which limits postprandial hyperglycemia. Despite its physiological importance, the specific gustatory mechanisms that elicit CPIR have not been clearly defined. While most studies point to glucose and glucose-containing saccharides (e.g., sucrose, maltodextrins) as being the most consistent elicitors, it is not apparent whether this is due to the detection of glucose per se, or to the perceived taste cues associated with these stimuli (e.g., sweetness, starchiness). This study investigated potential sensory mechanisms involved with eliciting CPIR in humans, focusing on the role of oral glucose detection and associated taste. Four stimulus conditions possessing different carbohydrate and taste profiles were designed: 1) glucose alone; 2) glucose mixed with lactisole, a sweet taste inhibitor; 3) maltodextrin, which is digested to starchy- and sweet-tasting products during oral processing; and 4) maltodextrin mixed with lactisole and acarbose, an oral digestion inhibitor. Healthy adults (N = 22) attended four sessions where blood samples were drawn before and after oral stimulation with one of the target stimuli. Plasma c-peptide, insulin, and glucose concentrations were then analyzed. Whereas glucose alone elicited CPIR (one-sample t-test, p < 0.05), it did not stimulate the response in the presence of lactisole. Likewise, maltodextrin alone stimulated CPIR (p < 0.05), but maltodextrin with lactisole and acarbose did not. Together, these findings indicate that glucose is an effective CPIR stimulus, but that an associated taste sensation also serves as an important cue for triggering this response in humans.
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Affiliation(s)
- Alexa J Pullicin
- Department of Food Science and Technology, Oregon State University, Corvallis, OR, USA
| | - Daniel Wils
- Nutrition and Health Department, Roquette Frères, Lestrem, France
| | - Juyun Lim
- Department of Food Science and Technology, Oregon State University, Corvallis, OR, USA.
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Martin LE, Andrewson TS, Penner MH, Lim J. Taste Detection of Maltooligosaccharides with Varying Degrees of Polymerization. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:6699-6705. [PMID: 37083361 PMCID: PMC10561598 DOI: 10.1021/acs.jafc.3c00910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Previous studies have shown that humans can taste maltooligosaccharides [MOS; degree of polymerization (DP) of 3-20] but not maltopolysaccharides (MPS; DP of >20) and that their taste detection is independent of the canonical sweet taste receptor. The objectives of this study were to determine the DP ranges of target stimuli that are tasted and further to investigate the impact of DP on taste detectability. To achieve this goal, we prepared three food-grade MOS samples with narrow DP ranges using flash chromatography: low (4-6), medium (7-12), and high (14-21) DP samples. Following sample preparation, we asked subjects to discriminate the MOS stimuli from blanks after the stimuli were swabbed on the tip of tongue. All stimuli were initially presented at 75 mM. Acarbose, an α-glucosidase inhibitor, was added to all stimuli, including blanks, to prevent oral hydrolysis of MOS. After determining that all three MOS samples were detected at a significant degree, we conducted follow-up studies to explore whether the detection of these samples differed at a range of concentrations (18-56 mM). The results showed that detection rates of medium- and high-DP MOS varied in a concentration-dependent manner (p < 0.05). In contrast, low-DP MOS showed a consistent detection rate across concentrations tested. These results demonstrate that humans can taste MOS stimuli of all chain lengths and that relative taste detection rates are generally similar across MOS with varying chain lengths.
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Affiliation(s)
- Laura E. Martin
- Department of Food Science and Technology, Oregon State University, Corvallis, OR, USA
- These authors contributed equally
| | - Toren S. Andrewson
- Department of Food Science and Technology, Oregon State University, Corvallis, OR, USA
- These authors contributed equally
| | - Michael H. Penner
- Department of Food Science and Technology, Oregon State University, Corvallis, OR, USA
| | - Juyun Lim
- Department of Food Science and Technology, Oregon State University, Corvallis, OR, USA
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Ascencio Gutierrez V, Simental Ramos A, Khayoyan S, Schier LA. Dietary experience with glucose and fructose fosters heightened avidity for glucose-containing sugars independent of TRPM5 taste transduction in mice. Nutr Neurosci 2023; 26:345-356. [PMID: 35311614 PMCID: PMC9810270 DOI: 10.1080/1028415x.2022.2050092] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Experience with metabolically distinct sugars, glucose and fructose, enhances attraction to the orosensory properties of glucose over fructose. To gain insight into which sensory signals are affected, we investigated how this nutritive learning reshapes behavioral responding to various sugars in brief access taste tests in C57BL6/J (B6) mice and assessed whether sugar-exposed mice lacking the TRPM5 channel involved in G-protein coupled taste transduction could acquire these types of preferences for glucose-containing sugars. METHODS B6, TRPM5 knockout (KO), and TRPM5 heterozygous (Het) mice were given extensive access to water (sugar naïve) or 0.316, 0.56, and 1.1 M glucose and fructose (sugar-exposed) and then tested, whilst food deprived, for their relative avidities for glucose, fructose, sucrose, maltose, and/or a non-metabolizable glucose analog in a series of taste tests. RESULTS Sugar-exposed B6 mice licked relatively more for glucose than fructose, driven by an increased avidity for glucose, not an avoidance of fructose, and licked more for maltose, compared to their sugar-naïve counterparts. Sugar-exposed B6 mice did not lick with such avidity for a non-metabolizable glucose analog. TRPM5 KO mice took longer to acquire the sugar discrimination than the Het controls, but both groups ultimately licked significantly more for glucose than fructose. Het mice displayed clear preferential licking for sucrose over fructose, while licking comparably high for glucose, sucrose, and maltose. KO mice licked significantly more for maltose than sucrose. CONCLUSIONS Collectively, the findings suggest that ingestive experience with glucose and fructose primarily reprograms behavioral responding to a TRPM5-independent orosensory signal generated by glucose-containing sugars.
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Affiliation(s)
| | | | - Shushanna Khayoyan
- Department of Biological Sciences, University of Southern California, Los Angeles, CA
| | - Lindsey A. Schier
- Department of Biological Sciences, University of Southern California, Los Angeles, CA
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10
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Martin LE, Lim J. OUP accepted manuscript. Chem Senses 2022; 47:6565984. [PMID: 35397161 PMCID: PMC8994581 DOI: 10.1093/chemse/bjac006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Oligosaccharides, a subclass of complex carbohydrates, occur both naturally in foods and as a result of oral starch digestion. We have previously shown that humans can taste maltooligosaccharides (MOS) and that their detection is independent of the canonical sweet taste receptor. While MOSs most commonly occur in a linear form, they can also exist in cyclic structures, referred to as cyclodextrins (CD). The aim of this study was to investigate how the structure of the MOS backbone (i.e. cyclic form) and the size (i.e. degree of polymerization; DP) affect their taste perception. We tested taste detection of cyclodextrins with DP of 6, 7, and 8 (i.e. α-, β-, and γ-CD, respectively) in the presence and absence of lactisole, a sweet receptor antagonist. We found that subjects could detect the taste of cyclodextrins in aqueous solutions at a significant level (P < 0.05), but were not able to detect them in the presence of lactisole (P > 0.05). These findings suggest that the cyclodextrins, unlike their linear analogs, are ligands of the human sweet taste receptor, hT1R2/hT1R3. Study findings are discussed in terms of how chemical structures may contribute to tastes of saccharides.
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Affiliation(s)
- Laura E Martin
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, USA
| | - Juyun Lim
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, USA
- Corresponding author: Department of Food Science and Technology, Oregon State University, 100 Wiegand Hall, Corvallis, OR 97331, USA.
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11
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Malone IG, Hunter BK, Rossow HL, Herzog H, Zolotukhin S, Munger SD, Dotson CD. Y1 receptors modulate taste-related behavioral responsiveness in male mice to prototypical gustatory stimuli. Horm Behav 2021; 136:105056. [PMID: 34509673 PMCID: PMC8640844 DOI: 10.1016/j.yhbeh.2021.105056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 08/16/2021] [Accepted: 08/19/2021] [Indexed: 10/20/2022]
Abstract
Mammalian taste bud cells express receptors for numerous peptides implicated elsewhere in the body in the regulation of metabolism, nutrient assimilation, and satiety. The perturbation of several peptide signaling pathways in the gustatory periphery results in changes in behavioral and/or physiological responsiveness to subsets of taste stimuli. We previously showed that Peptide YY (PYY) - which is present in both saliva and in subsets of taste cells - can affect behavioral taste responsiveness and reduce food intake and body weight. Here, we investigated the contributions of taste bud-localized receptors for PYY and the related Neuropeptide Y (NPY) on behavioral taste responsiveness. Y1R, but not Y2R, null mice show reduced responsiveness to sweet, bitter, and salty taste stimuli in brief-access taste tests; similar results were seen when wildtype mice were exposed to Y receptor antagonists in the taste stimuli. Finally, mice in which the gene encoding the NPY propeptide was deleted also showed reduced taste responsiveness to sweet and bitter taste stimuli. Collectively, these results suggest that Y1R signaling, likely through its interactions with NPY, can modulate peripheral taste responsiveness in mice.
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Affiliation(s)
- Ian G Malone
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Brianna K Hunter
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Heidi L Rossow
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | | | - Sergei Zolotukhin
- Center for Smell and Taste, University of Florida, Gainesville, FL 32610, USA; Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Steven D Munger
- Center for Smell and Taste, University of Florida, Gainesville, FL 32610, USA; Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL 32610, USA; Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Cedrick D Dotson
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA.
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12
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Jarvie BC, Chen JY, King HO, Palmiter RD. Satb2 neurons in the parabrachial nucleus mediate taste perception. Nat Commun 2021. [PMID: 33431851 DOI: 10.1038/s41467‐020‐20100‐8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The neural circuitry mediating taste has been mapped out from the periphery to the cortex, but genetic identity of taste-responsive neurons has remained elusive. Here, we describe a population of neurons in the gustatory region of the parabrachial nucleus that express the transcription factor Satb2 and project to taste-associated regions, including the gustatory thalamus and insular cortex. Using calcium imaging in awake, freely licking mice, we show that Satb2 neurons respond to the five basic taste modalities. Optogenetic activation of these neurons enhances taste preferences, whereas chronic inactivation decreases the magnitude of taste preferences in both brief- and long-access taste tests. Simultaneous inactivation of Satb2 and calcitonin gene-related peptide neurons in the PBN abolishes responses to aversive tastes. These data suggest that taste information in the parabrachial nucleus is conveyed by multiple populations of neurons, including both Satb2 and calcitonin gene-related peptide neurons.
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Affiliation(s)
- Brooke C Jarvie
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA.,Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Jane Y Chen
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA.,Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Hunter O King
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA
| | - Richard D Palmiter
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA. .,Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA. .,Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
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13
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Jarvie BC, Chen JY, King HO, Palmiter RD. Satb2 neurons in the parabrachial nucleus mediate taste perception. Nat Commun 2021; 12:224. [PMID: 33431851 PMCID: PMC7801645 DOI: 10.1038/s41467-020-20100-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 11/10/2020] [Indexed: 11/09/2022] Open
Abstract
The neural circuitry mediating taste has been mapped out from the periphery to the cortex, but genetic identity of taste-responsive neurons has remained elusive. Here, we describe a population of neurons in the gustatory region of the parabrachial nucleus that express the transcription factor Satb2 and project to taste-associated regions, including the gustatory thalamus and insular cortex. Using calcium imaging in awake, freely licking mice, we show that Satb2 neurons respond to the five basic taste modalities. Optogenetic activation of these neurons enhances taste preferences, whereas chronic inactivation decreases the magnitude of taste preferences in both brief- and long-access taste tests. Simultaneous inactivation of Satb2 and calcitonin gene-related peptide neurons in the PBN abolishes responses to aversive tastes. These data suggest that taste information in the parabrachial nucleus is conveyed by multiple populations of neurons, including both Satb2 and calcitonin gene-related peptide neurons.
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Affiliation(s)
- Brooke C Jarvie
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Jane Y Chen
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Hunter O King
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA
| | - Richard D Palmiter
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA.
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
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An alternative pathway for sweet sensation: possible mechanisms and physiological relevance. Pflugers Arch 2020; 472:1667-1691. [PMID: 33030576 DOI: 10.1007/s00424-020-02467-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/14/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022]
Abstract
Sweet substances are detected by taste-bud cells upon binding to the sweet-taste receptor, a T1R2/T1R3 heterodimeric G protein-coupled receptor. In addition, experiments with mouse models lacking the sweet-taste receptor or its downstream signaling components led to the proposal of a parallel "alternative pathway" that may serve as metabolic sensor and energy regulator. Indeed, these mice showed residual nerve responses and behavioral attraction to sugars and oligosaccharides but not to artificial sweeteners. In analogy to pancreatic β cells, such alternative mechanism, to sense glucose in sweet-sensitive taste cells, might involve glucose transporters and KATP channels. Their activation may induce depolarization-dependent Ca2+ signals and release of GLP-1, which binds to its receptors on intragemmal nerve fibers. Via unknown neuronal and/or endocrine mechanisms, this pathway may contribute to both, behavioral attraction and/or induction of cephalic-phase insulin release upon oral sweet stimulation. Here, we critically review the evidence for a parallel sweet-sensitive pathway, involved signaling mechanisms, neural processing, interactions with endocrine hormonal mechanisms, and its sensitivity to different stimuli. Finally, we propose its physiological role in detecting the energy content of food and preparing for digestion.
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15
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Dutta Banik D, Benfey ED, Martin LE, Kay KE, Loney GC, Nelson AR, Ahart ZC, Kemp BT, Kemp BR, Torregrossa AM, Medler KF. A subset of broadly responsive Type III taste cells contribute to the detection of bitter, sweet and umami stimuli. PLoS Genet 2020; 16:e1008925. [PMID: 32790785 PMCID: PMC7425866 DOI: 10.1371/journal.pgen.1008925] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 06/10/2020] [Indexed: 12/20/2022] Open
Abstract
Taste receptor cells use multiple signaling pathways to detect chemicals in potential food items. These cells are functionally grouped into different types: Type I cells act as support cells and have glial-like properties; Type II cells detect bitter, sweet, and umami taste stimuli; and Type III cells detect sour and salty stimuli. We have identified a new population of taste cells that are broadly tuned to multiple taste stimuli including bitter, sweet, sour, and umami. The goal of this study was to characterize these broadly responsive (BR) taste cells. We used an IP3R3-KO mouse (does not release calcium (Ca2+) from internal stores in Type II cells when stimulated with bitter, sweet, or umami stimuli) to characterize the BR cells without any potentially confounding input from Type II cells. Using live cell Ca2+ imaging in isolated taste cells from the IP3R3-KO mouse, we found that BR cells are a subset of Type III cells that respond to sour stimuli but also use a PLCβ signaling pathway to respond to bitter, sweet, and umami stimuli. Unlike Type II cells, individual BR cells are broadly tuned and respond to multiple stimuli across different taste modalities. Live cell imaging in a PLCβ3-KO mouse confirmed that BR cells use this signaling pathway to respond to bitter, sweet, and umami stimuli. Short term behavioral assays revealed that BR cells make significant contributions to taste driven behaviors and found that loss of either PLCβ3 in BR cells or IP3R3 in Type II cells caused similar behavioral deficits to bitter, sweet, and umami stimuli. Analysis of c-Fos activity in the nucleus of the solitary tract (NTS) also demonstrated that functional Type II and BR cells are required for normal stimulus induced expression. We use our taste system to decide if we are going to consume or reject a potential food item. This is critical for survival, as we need energy to live but also need to avoid potentially toxic compounds. Therefore, it is important to understand how the taste cells in our mouth detect the chemicals in food and send a message to our brain. Signals from the taste cells form a code that conveys information about the nature of the potential food item to the brain. How this taste coding works is not well understood. Currently, it is thought that taste cells are primarily selective for each taste stimuli and only detect either bitter, sweet, sour, salt, or umami (amino acids) compounds. Our study describes a new population of taste cells that can detect multiple types of stimuli, including chemicals from different taste qualities. Thus, taste cells can be either selective or generally responsive to stimuli which is similar to the cells in the brain that process taste information. The presence of these broadly responsive taste cells provides new insight into how taste information is sent to the brain for processing.
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Affiliation(s)
- Debarghya Dutta Banik
- Department of Biological Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Eric D. Benfey
- Department of Biological Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Laura E. Martin
- Department of Psychology, University at Buffalo, Buffalo, New York, United States of America
| | - Kristen E. Kay
- Department of Psychology, University at Buffalo, Buffalo, New York, United States of America
| | - Gregory C. Loney
- Department of Psychology, University at Buffalo, Buffalo, New York, United States of America
| | - Amy R. Nelson
- Department of Biological Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Zachary C. Ahart
- Department of Biological Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Barrett T. Kemp
- Department of Biological Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Bailey R. Kemp
- Department of Biological Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Ann-Marie Torregrossa
- Department of Psychology, University at Buffalo, Buffalo, New York, United States of America
- Center for Ingestive Behavior Research, University at Buffalo, Buffalo, New York, United States of America
| | - Kathryn F. Medler
- Department of Biological Sciences, University at Buffalo, Buffalo, New York, United States of America
- Center for Ingestive Behavior Research, University at Buffalo, Buffalo, New York, United States of America
- * E-mail:
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16
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Andres-Hernando A, Kuwabara M, Orlicky DJ, Vandenbeuch A, Cicerchi C, Kinnamon SC, Finger TE, Johnson RJ, Lanaspa MA. Sugar causes obesity and metabolic syndrome in mice independently of sweet taste. Am J Physiol Endocrinol Metab 2020; 319:E276-E290. [PMID: 32574112 PMCID: PMC7473911 DOI: 10.1152/ajpendo.00529.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Intake of sugars, especially the fructose component, is strongly associated with the development of obesity and metabolic syndrome, but the relative role of taste versus metabolism in driving preference, intake, and metabolic outcome is not fully understood. We aimed to evaluate the preference for sweet substances and the tendency to develop metabolic syndrome in response to these sugars in mice lacking functional taste signaling [P2X2 (P2X purinoreceptor 2)/P2X3 (P2X purinoreceptor 3) double knockout mice (DKO)] and mice unable to metabolize fructose (fructokinase knockout mice). Of interest, our data indicate that despite their inability to taste sweetness, P2X2/3 DKO mice still prefer caloric sugars (including fructose and glucose) to water in long-term testing, although with diminished preference compared with control mice. Despite reduced intake of caloric sugars by P2X2/3 DKO animals, the DKO mice still show increased levels of the sugar-dependent hormone FGF21 (fibroblast growth factor 21) in plasma and liver. Despite lower sugar intake, taste-blind mice develop severe features of metabolic syndrome due to reduced sensitivity to leptin, reduced ability to mobilize and oxidize fats, and increased hepatic de novo lipogenesis. In contrast to P2X2/3 DKO and wild-type mice, fructokinase knockout mice, which cannot metabolize fructose and are protected against fructose-induced metabolic syndrome, demonstrate reduced preference and intake for all fructose-containing sugars tested but not for glucose or artificial sweeteners. Based on these observations, we conclude that sugar can induce metabolic syndrome in mice independently of its sweet properties. Furthermore, our data demonstrate that the metabolism of fructose is necessary for sugar to drive intake and preference in mice.
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Affiliation(s)
- Ana Andres-Hernando
- Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
| | - Masanari Kuwabara
- Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
| | - David J Orlicky
- Department of Pathology, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
| | - Aurelie Vandenbeuch
- Department of Otolaryngology, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
| | - Christina Cicerchi
- Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
| | - Sue C Kinnamon
- Department of Otolaryngology, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
| | - Thomas E Finger
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
| | - Richard J Johnson
- Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
| | - Miguel A Lanaspa
- Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, University of Colorado, Aurora, Colorado
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Sclafani A, Zukerman S, Ackroff K. Residual Glucose Taste in T1R3 Knockout but not TRPM5 Knockout Mice. Physiol Behav 2020; 222:112945. [PMID: 32417232 DOI: 10.1016/j.physbeh.2020.112945] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/29/2020] [Accepted: 04/29/2020] [Indexed: 12/19/2022]
Abstract
Knockout (KO) mice missing the sweet taste receptor subunit T1R3 or the signaling protein TRPM5 have greatly attenuated sweetener preferences. Yet both types of KO mice develop preferences for glucose but not fructose in 24-h tests, which has been attributed to the postoral reinforcing actions of glucose. Here we probed for residual sugar taste sensitivity in KO mice. Unlike wildtype (WT) mice, food-restricted T1R3 KO and TRPM5 KO mice displayed little attraction for 8% glucose and 8% fructose in 1-min, two-bottle choice tests. However, in 1-h tests about half of the T1R3 KO mice displayed a significant preference for glucose over fructose (78-84%), while WT mice showed either no or weak preferences (41-56%) for glucose. Following one-bottle training sessions, WT mice display greater glucose preferences although still weaker than those observed in T1R3 KO mice. In contrast, TRPM5 KO mice were indifferent to sugars in 1-h tests but developed a strong preference for glucose over fructose in 24-h tests. T1R3 taste cells contain the sodium glucose cotransporter 1 (SGLT1) and the ATP-gated K+ (KATP) metabolic sensor, which may mediate the unlearned glucose preference displayed by T1R3 KO mice. Unlike WT mice, many T1R3 KO mice strongly preferred glucose to a non-metabolizable glucose analog (α-methyl-D-glucopyranoside, MDG) in initial 1-h choice tests. Glucose and MDG are both ligands for SGLT1 which indicates that SGLT1 sensing does not mediate the glucose preference of T1R3 KO mice. Instead, KATP sensing and/or other oral sensors are implicated. The MDG findings also argue against postoral sensing as the primary source of the initial glucose preference displayed by T1R3 KO mice. Why only half of the T1R3 KO mice showed this preference in 1-h tests remains to be determined. All T1R3 KO mice preferred glucose to fructose in 24-h tests, which appears to be due to both oral and postoral glucose sensing.
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Affiliation(s)
- Anthony Sclafani
- Department of Psychology, Brooklyn College of City University of New York, Brooklyn, New York 11210, USA.
| | - Steven Zukerman
- Department of Psychology, Brooklyn College of City University of New York, Brooklyn, New York 11210, USA
| | - Karen Ackroff
- Department of Psychology, Brooklyn College of City University of New York, Brooklyn, New York 11210, USA
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18
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Glendinning JI, Maleh J, Ortiz G, Touzani K, Sclafani A. Olfaction contributes to the learned avidity for glucose relative to fructose in mice. Am J Physiol Regul Integr Comp Physiol 2020; 318:R901-R916. [DOI: 10.1152/ajpregu.00340.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
When offered glucose and fructose solutions, rodents consume more glucose solution because it produces stronger postoral reinforcement. Intake of these sugars also conditions a higher avidity for glucose relative to fructose. We asked which chemosensory cue mediates the learned avidity for glucose. We subjected mice to 18 days of sugar training, offering them 0.3, 0.6, and 1 M glucose and fructose solutions. Before and after training, we measured avidity for 0.3 and 0.6 M glucose and fructose in brief-access lick tests. First, we replicated prior work in C57BL/6 mice. Before training, the mice licked at a slightly higher rate for 0.6 M fructose; after training, they licked at a higher rate for 0.6 M glucose. Second, we assessed the necessity of the glucose-specific ATP-sensitive K+(KATP) taste pathway for the learned avidity for glucose, using mice with a nonfunctional KATPchannel [regulatory sulfonylurea receptor (SUR1) knockout (KO) mice]. Before training, SUR1 KO and wild-type mice licked at similar rates for 0.6 M glucose and fructose; after training, both strains licked at a higher rate for 0.6 M glucose, indicating that the KATPpathway is not necessary for the learned discrimination. Third, we investigated the necessity of olfaction by comparing sham-treated and anosmic mice. The mice were made anosmic by olfactory bulbectomy or ZnSO4treatment. Before training, sham-treated and anosmic mice licked at similar rates for 0.6 M glucose and fructose; after training, sham-treated mice licked at a higher rate for 0.6 M glucose, whereas anosmic mice licked at similar rates for both sugars. This demonstrates that olfaction contributes significantly to the learned avidity for glucose.
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Affiliation(s)
- John I. Glendinning
- Departments of Biology and Neuroscience and Behavior, Barnard College, Columbia University, New York, New York
| | - Jennifer Maleh
- Departments of Biology and Neuroscience and Behavior, Barnard College, Columbia University, New York, New York
| | - Gabriella Ortiz
- Departments of Biology and Neuroscience and Behavior, Barnard College, Columbia University, New York, New York
| | - Khalid Touzani
- Department of Psychology, Brooklyn College of City University of New York, Brooklyn, New York
| | - Anthony Sclafani
- Department of Psychology, Brooklyn College of City University of New York, Brooklyn, New York
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19
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Neural Isolation of the Olfactory Bulbs Severely Impairs Taste-Guided Behavior to Normally Preferred, But Not Avoided, Stimuli. eNeuro 2020; 7:ENEURO.0026-20.2020. [PMID: 32152061 PMCID: PMC7142272 DOI: 10.1523/eneuro.0026-20.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 02/24/2020] [Accepted: 02/27/2020] [Indexed: 12/02/2022] Open
Abstract
Here we systematically tested the hypothesis that motivated behavioral responsiveness to preferred and avoided taste compounds is relatively independent of the olfactory system in mice whose olfactory bulbs (main and accessory) were surgically disconnected from the rest of the brain [bulbotomy (BULBx)]. BULBx was confirmed histologically as well as functionally with the buried food test. In brief access taste tests, animals received 10-s trials of various concentrations of a taste compound delivered quasirandomly. BULBx C57BL/6 (B6) mice displayed severely blunted concentration-dependent licking for the disaccharide sucrose, the maltodextrin Maltrin, and the fat emulsion Intralipid relative to their sham-operated controls (SHAM B6). Licking for the noncaloric sweetener saccharin was also blunted by bulbotomy, but less so. As expected, mice lacking a functional “sweet” receptor [T1R2+T1R3 knockout (KO)] displayed concentration-dependent responsiveness to Maltrin and severely attenuated licking to sucrose. Like in B6 mice, responsiveness to both stimuli was exceptionally curtailed by bulbotomy. In contrast to these deficits in taste-guided behavior for unconditionally preferred stimuli, BULBx in B6 and KO mice did not alter concentration-dependent decreases for the representative avoided stimuli quinine and citric acid. Nor did it temper the intake of and preference for high concentrations of affectively positive stimuli when presented in long-term (23-h) two-bottle tests, demonstrating that the surgery does not lead to a generalized motivational deficit. Collectively, these behavioral results demonstrate that specific aspects of taste-guided ingestive motivation are profoundly disturbed by eliminating the anatomic connections between the main/accessory olfactory bulbs and the rest of the brain.
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20
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Kalyanasundar B, Blonde GD, Spector AC, Travers SP. Electrophysiological responses to sugars and amino acids in the nucleus of the solitary tract of type 1 taste receptor double-knockout mice. J Neurophysiol 2020; 123:843-859. [PMID: 31913749 DOI: 10.1152/jn.00584.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Strong evidence supports a major role for heterodimers of the type 1 taste receptor (T1R) family in the taste transduction of sugars (T1R2+T1R3) and amino acids (T1R1+T1R3), but there are also neural and behavioral data supporting T1R-independent mechanisms. Most neural evidence for alternate mechanisms comes from whole nerve recordings in mice with deletion of a single T1R family member, limiting conclusions about the functional significance and T1R independence of the remaining responses. To clarify these issues, we recorded single-unit taste responses from the nucleus of the solitary tract in T1R double-knockout (double-KO) mice lacking functional T1R1+T1R3 [KO1+3] or T1R2+T1R3 [KO2+3] receptors and their wild-type background strains [WT; C57BL/6J (B6), 129X1/SvJ (S129)]. In both double-KO strains, responses to sugars and a moderate concentration of an monosodium glutamate + amiloride + inosine 5'-monophosphate cocktail (0.1 M, i.e., umami) were profoundly depressed, whereas a panel of 0.6 M amino acids were mostly unaffected. Strikingly, in contrast to WT mice, no double-KO neurons responded selectively to sugars and umami, precluding segregation of this group of stimuli from those representing other taste qualities in a multidimensional scaling analysis. Nevertheless, residual sugar responses, mainly elicited by monosaccharides, persisted as small "sideband" responses in double-KOs. Thus other receptors may convey limited information about sugars to the central nervous system, but T1Rs appear critical for coding the distinct perceptual features of sugar and umami stimuli. The persistence of amino acid responses supports previous proposals of alternate receptors, but because these stimuli affected multiple neuron types, further investigations are necessary.NEW & NOTEWORTHY The type 1 taste receptor (T1R) family is crucial for transducing sugars and amino acids, but there is evidence for T1R-independent mechanisms. In this study, single-unit recordings from the nucleus of the solitary tract in T1R double-knockout mice lacking T1R1+T1R3 or T1R2+T1R3 receptors revealed greatly reduced umami synergism and sugar responses. Nevertheless, residual sugar responses persisted, mainly elicited by monosaccharides and evident as "sidebands" in neurons activated more vigorously by other qualities.
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Affiliation(s)
- B Kalyanasundar
- Division of Biosciences, College of Dentistry, Ohio State University, Columbus, Ohio
| | - Ginger D Blonde
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
| | - Susan P Travers
- Division of Biosciences, College of Dentistry, Ohio State University, Columbus, Ohio
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21
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Huang AY. Immune Responses Alter Taste Perceptions: Immunomodulatory Drugs Shape Taste Signals during Treatments. J Pharmacol Exp Ther 2019; 371:684-691. [PMID: 31611237 DOI: 10.1124/jpet.119.261297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/08/2019] [Indexed: 01/01/2023] Open
Abstract
Considering that nutrients are required in health and diseases, the detection and ingestion of food to meet the requirements is attributable to the sense of taste. Altered taste sensations lead to a decreased appetite, which is usually one of the frequent causes of malnutrition in patients with diseases. Ongoing taste research has identified a variety of drug pathways that cause changes in taste perceptions in cancer, increasing our understanding of taste disturbances attributable to aberrant mechanisms of taste sensation. The evidence discussed in this review, which addresses the implications of innate immune responses in the modulation of taste functions, focuses on the adverse effects on taste transmission from taste buds by immune modulators responsible for alterations in the perceived intensity of some taste modalities. Another factor, damage to taste progenitor cells that directly results in local effects on taste buds, must also be considered in relation to taste disturbances in patients with cancer. Recent discoveries discussed have provided new insights into the pathophysiology of taste dysfunctions associated with the specific treatments. SIGNIFICANCE STATEMENT: The paradigm that taste signals transmitted to the brain are determined only by tastant-mediated activation via taste receptors has been challenged by the immune modification of taste transmission through drugs during the processing of gustatory information in taste buds. This article reports the findings in a model system (mouse taste buds) that explain the basis for the taste dysfunctions in patients with cancer that has long been observed but never understood.
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Affiliation(s)
- Anthony Y Huang
- Department of Anatomy and Center for Integrated Research in Cognitive and Neural Science, Southern Illinois University School of Medicine, Carbondale, Illinois
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22
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Lim J, Pullicin AJ. Oral carbohydrate sensing: Beyond sweet taste. Physiol Behav 2019; 202:14-25. [DOI: 10.1016/j.physbeh.2019.01.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 01/15/2019] [Accepted: 01/23/2019] [Indexed: 01/28/2023]
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23
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Treesukosol Y, Moran TH. Cross-Generalization Profile to Orosensory Stimuli of Rats Conditioned to Avoid a High Fat/High Sugar Diet. Chem Senses 2019; 43:181-188. [PMID: 29401249 DOI: 10.1093/chemse/bjy005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The orosensory characteristics of a diet play a role in its acceptance and rejection. The current study was designed to investigate the gustatory components that contribute to the intake of a palatable, high-energy diet (HE; 45% calories from fat, 17% calories from sucrose). Here, rats were conditioned to avoid HE diet by pairings with i.p. injections of LiCl to induce visceral malaise. Subsequently, the degree of generalization was tested to an array of taste compounds using a brief-access lick procedure (10-s trials, 30-min sessions). Compared to NaCl-injected controls, LiCl-injected rats suppressed licking response to 100% linoleic acid and 20% intralipid, and to a lesser extent 17% sucrose. There was more variability in the lick responses to sucrose among the LiCl-injected rats. Rats that tended to suppress licking responses to sucrose generalized this response to glucose, fructose and Na-saccharin but not to Polycose. In contrast, LiCl-injected rats did not significantly suppress lick responses to water, NaCl, citric acid, or quinine compared to controls rats. The brief access feature of this procedure, allows for behavioral measures when postingestive factors are minimized. These findings support a role for gustatory cues in the detection of high fat/high sugar diets. Furthermore, it appears that the fat component is a more salient orosensory feature of the HE diet.
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Affiliation(s)
- Yada Treesukosol
- Department of Psychology, California State University, Long Beach, CA, USA
| | - Timothy H Moran
- Department of Psychiatry and Behavioral Sciences, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.,Johns Hopkins Global Obesity Prevention Center, Johns Hopkins University, Baltimore, MD, USA
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24
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Schier LA, Spector AC. The Functional and Neurobiological Properties of Bad Taste. Physiol Rev 2019; 99:605-663. [PMID: 30475657 PMCID: PMC6442928 DOI: 10.1152/physrev.00044.2017] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 05/18/2018] [Accepted: 06/30/2018] [Indexed: 12/12/2022] Open
Abstract
The gustatory system serves as a critical line of defense against ingesting harmful substances. Technological advances have fostered the characterization of peripheral receptors and have created opportunities for more selective manipulations of the nervous system, yet the neurobiological mechanisms underlying taste-based avoidance and aversion remain poorly understood. One conceptual obstacle stems from a lack of recognition that taste signals subserve several behavioral and physiological functions which likely engage partially segregated neural circuits. Moreover, although the gustatory system evolved to respond expediently to broad classes of biologically relevant chemicals, innate repertoires are often not in register with the actual consequences of a food. The mammalian brain exhibits tremendous flexibility; responses to taste can be modified in a specific manner according to bodily needs and the learned consequences of ingestion. Therefore, experimental strategies that distinguish between the functional properties of various taste-guided behaviors and link them to specific neural circuits need to be applied. Given the close relationship between the gustatory and visceroceptive systems, a full reckoning of the neural architecture of bad taste requires an understanding of how these respective sensory signals are integrated in the brain.
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Affiliation(s)
- Lindsey A Schier
- Department of Biological Sciences, University of Southern California , Los Angeles, California ; and Department of Psychology and Program in Neuroscience, Florida State University , Tallahassee, Florida
| | - Alan C Spector
- Department of Biological Sciences, University of Southern California , Los Angeles, California ; and Department of Psychology and Program in Neuroscience, Florida State University , Tallahassee, Florida
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25
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Kreuch D, Keating DJ, Wu T, Horowitz M, Rayner CK, Young RL. Gut Mechanisms Linking Intestinal Sweet Sensing to Glycemic Control. Front Endocrinol (Lausanne) 2018; 9:741. [PMID: 30564198 PMCID: PMC6288399 DOI: 10.3389/fendo.2018.00741] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/22/2018] [Indexed: 12/25/2022] Open
Abstract
Sensing nutrients within the gastrointestinal tract engages the enteroendocrine cell system to signal within the mucosa, to intrinsic and extrinsic nerve pathways, and the circulation. This signaling provides powerful feedback from the intestine to slow the rate of gastric emptying, limit postprandial glycemic excursions, and induce satiation. This review focuses on the intestinal sensing of sweet stimuli (including low-calorie sweeteners), which engage similar G-protein-coupled receptors (GPCRs) to the sweet taste receptors (STRs) of the tongue. It explores the enteroendocrine cell signals deployed upon STR activation that act within and outside the gastrointestinal tract, with a focus on the role of this distinctive pathway in regulating glucose transport function via absorptive enterocytes, and the associated impact on postprandial glycemic responses in animals and humans. The emerging role of diet, including low-calorie sweeteners, in modulating the composition of the gut microbiome and how this may impact glycemic responses of the host, is also discussed, as is recent evidence of a causal role of diet-induced dysbiosis in influencing the gut-brain axis to alter gastric emptying and insulin release. Full knowledge of intestinal STR signaling in humans, and its capacity to engage host and/or microbiome mechanisms that modify glycemic control, holds the potential for improved prevention and management of type 2 diabetes.
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Affiliation(s)
- Denise Kreuch
- Faculty of Health and Medical Sciences & Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
| | - Damien J. Keating
- College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
- Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Tongzhi Wu
- Faculty of Health and Medical Sciences & Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
| | - Michael Horowitz
- Faculty of Health and Medical Sciences & Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
| | - Christopher K. Rayner
- Faculty of Health and Medical Sciences & Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
| | - Richard L. Young
- Faculty of Health and Medical Sciences & Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
- Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
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Dastugue A, Merlin JF, Maquart G, Bernard A, Besnard P. A New Method for Studying Licking Behavior Determinants in Rodents: Application to Diet-Induced Obese Mice. Obesity (Silver Spring) 2018; 26:1905-1914. [PMID: 30369067 DOI: 10.1002/oby.22342] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 09/19/2018] [Accepted: 09/20/2018] [Indexed: 01/08/2023]
Abstract
OBJECTIVE An original device for exploring taste-guided reward behavior in rodents using a newly designed computer-controlled liquid delivery system equipped with "lickometers" is described. METHODS This octagonal shaped "gustometer" is composed of eight shutters that give random access during a few seconds to eight bottles delivering different liquid stimuli. This original design, which forces the animal to move for access to the drinking source, allows a simultaneous analysis of the licking behavior and motivation to drink. Determination of the sucrose licking behavior in diet-induced obese mice was used to validate this method because nutritional obesity disturbs the sweet taste perception in rodents. RESULTS A rise in sucrose response threshold and a decrease in the motivation to drink sweet solutions were found in mice fed the obesogenic diet. These data were highly reproducible among independent studies and corroborated the existence of functional links between diet-induced obesity and gustation in rodents. CONCLUSIONS The FRM-8 gustometer appears to be especially suitable for exploring determinants of behavioral outputs in response to oro-sensory stimuli in the mouse. It also provides substantial information on the taste-reward relationship, useful for better understanding the origin of gustatory efficiency or, conversely, dysfunction, as reported in nutritional obesity.
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Affiliation(s)
- Aurélie Dastugue
- Physiologie de la Nutrition et Toxicologie (NUTox), UMRU1231 Lipids, Nutrition, Cancer, INSERM Research Group, University of Burgundy Franche-Comté, Dijon, France
| | - Jean-François Merlin
- Physiologie de la Nutrition et Toxicologie (NUTox), UMRU1231 Lipids, Nutrition, Cancer, INSERM Research Group, University of Burgundy Franche-Comté, Dijon, France
| | - Guillaume Maquart
- Physiologie de la Nutrition et Toxicologie (NUTox), UMRU1231 Lipids, Nutrition, Cancer, INSERM Research Group, University of Burgundy Franche-Comté, Dijon, France
| | - Arnaud Bernard
- Physiologie de la Nutrition et Toxicologie (NUTox), UMRU1231 Lipids, Nutrition, Cancer, INSERM Research Group, University of Burgundy Franche-Comté, Dijon, France
| | - Philippe Besnard
- Physiologie de la Nutrition et Toxicologie (NUTox), UMRU1231 Lipids, Nutrition, Cancer, INSERM Research Group, University of Burgundy Franche-Comté, Dijon, France
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Sclafani A, Vural AS, Ackroff K. Profound differences in fat versus carbohydrate preferences in CAST/EiJ and C57BL/6J mice: Role of fat taste. Physiol Behav 2018; 194:348-355. [PMID: 29933030 PMCID: PMC6082157 DOI: 10.1016/j.physbeh.2018.06.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 06/12/2018] [Indexed: 11/24/2022]
Abstract
In a nutrient self-selection study, CAST/EiJ mice consumed more carbohydrate than fat while C57BL/6J (B6) mice showed the opposite preference. The present study revealed similar strain differences in preferences for isocaloric fat (Intralipid) and carbohydrate (sucrose, maltodextrin) solutions in chow-fed mice. In initial 2-day choice tests, percent fat intakes of CAST and B6 mice were 4-9% and 71-81% respectively. In subsequent nutrient vs. water tests, CAST mice consumed considerably less fat but not carbohydrate compared to B6 mice. Orosensory rather than postoral factors are implicated in the very low fat preference and intake of CAST mice. This is supported by results of a choice test with Intralipid mixed with non-nutritive sweeteners vs. non-sweet maltodextrin. The preference of CAST mice for sweetened fat exceeded that of B6 mice (94 vs. 74%) and absolute fat intakes were similar in the two strains. When given unsweetened Intralipid vs. water tests at ascending fat concentrations CAST mice displayed reduced fat preferences at 0.1-5% and reduced intakes at 0.5-5% concentrations, compared to B6 mice. The differential fat preferences of CAST and B6 mice may reflect differences in fat taste sensing or in central neural processes related to fat selection.
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Affiliation(s)
- Anthony Sclafani
- Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA.
| | - Austin S Vural
- Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
| | - Karen Ackroff
- Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
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Sclafani A, Ackroff K. Role of lipolysis in postoral and oral fat preferences in mice. Am J Physiol Regul Integr Comp Physiol 2018; 315:R434-R441. [PMID: 29668321 PMCID: PMC6172632 DOI: 10.1152/ajpregu.00014.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 03/20/2018] [Accepted: 04/11/2018] [Indexed: 11/22/2022]
Abstract
Fatty acid receptors in the mouth and gut are implicated in the appetite for fat-rich foods. The role of lipolysis in oral- and postoral-based fat preferences of C57BL/6J mice was investigated by inhibiting lipase enzymes with orlistat. Experiment 1 showed that postoral lipolysis is required: mice learned to prefer (by 70%) a flavored solution paired with intragastric infusions of 5% soybean oil but not a flavor paired with soybean oil + orlistat (4 mg/g fat) infusions. Experiments 2-4 tested the oral attraction to oil in mice given brief choice tests that minimize postoral effects. In experiment 2, the same low orlistat dose did not reduce the strong (83-94%) preference for 2.5 or 5% soybean oil relative to fat-free vehicle in 3-min tests. Mice in experiment 3 given choice tests between two fat emulsions (2% triolein, corn oil, or soybean oil) with or without orlistat at a high dose (250 mg/g fat) preferred triolein (72%) and soybean oil (67%) without orlistat to the oil with orlistat but were indifferent to corn oil with and without orlistat. In experiment 4, mice preferred 2% triolein (62%) or soybean oil (89%) to vehicle when both choices contained orlistat (250 mg/g fat). Fatty acid receptors are thus essential for postoral but not oral-based preferences. Both triglyceride and fatty acid taste receptors may mediate oral fat preferences.
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Affiliation(s)
- Anthony Sclafani
- Brooklyn College and the Graduate School, City University of New York , Brooklyn, New York
| | - Karen Ackroff
- Brooklyn College and the Graduate School, City University of New York , Brooklyn, New York
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Sclafani A. From appetite setpoint to appetition: 50years of ingestive behavior research. Physiol Behav 2018; 192:210-217. [PMID: 29305256 PMCID: PMC6019132 DOI: 10.1016/j.physbeh.2018.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 12/06/2017] [Accepted: 01/01/2018] [Indexed: 12/17/2022]
Abstract
I review the main themes of my 50-year research career in ingestive behavior as a graduate student at the University of Chicago and a professor at the City University of New York. A seminar course with my Ph.D. mentor, S. P. Grossman, sparked my interest in the hypothalamic obesity syndrome. I developed a wire knife to dissect the neuropathways and the functional disorder responsible for the syndrome. An elevated appetite setpoint that permitted the overconsumption of palatable foods appeared central to the hypothalamic syndrome. In brain-intact rats, providing an assortment of highly palatable foods (the cafeteria diet) stimulated diet-induced obesity that mimicked elements of hypothalamic obesity. Studies of the determinants of food palatability led to the discovery of a "new" carbohydrate taste (maltodextrin taste) and the confirmation of a fatty taste. In addition to oral taste receptors, gut nutrient sensors stimulated the intake/preference for carbohydrate- and fat-rich foods via an appetition process that stimulates brain reward systems. My research career greatly benefited from many diligent and creative students, collaborators and technicians and research support from my university and the National Institutes of Health.
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Affiliation(s)
- Anthony Sclafani
- Department of Psychology, Brooklyn College and the Graduate Center of the City University of New York, 2900 Bedford Ave, Brooklyn, NY 11210, USA.
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Chegeni M, Amiri M, Nichols BL, Nairn HY, Hamaker BR. Dietary starch breakdown product sensing mobilizes and apically activates α‐glucosidases in small intestinal enterocytes. FASEB J 2018; 32:3903-3911. [DOI: 10.1096/fj.201701029r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mohammad Chegeni
- Department of Food ScienceWhistler Center for Carbohydrate ResearchPurdue UniversityWest LafayetteIndianaUSA
| | - Mahdi Amiri
- Department of Physiological ChemistryUniversity of Veterinary Medicine HannoverHannoverGermany
- Department of Gastroenterology, Hepatology, and EndocrinologyHannover Medical SchoolHannoverGermany
| | - Buford L. Nichols
- Department of PediatricsU.S. Department of Agriculture/Agricultural Research ServiceChildren's Nutrition Research CenterBaylor College of MedicineHoustonTexasUSA
| | - Hassan Y. Nairn
- Department of Physiological ChemistryUniversity of Veterinary Medicine HannoverHannoverGermany
| | - Bruce R. Hamaker
- Department of Food ScienceWhistler Center for Carbohydrate ResearchPurdue UniversityWest LafayetteIndianaUSA
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31
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Lapis TJ, Penner MH, Balto AS, Lim J. Oral Digestion and Perception of Starch: Effects of Cooking, Tasting Time, and Salivary α-Amylase Activity. Chem Senses 2018; 42:635-645. [PMID: 28981820 DOI: 10.1093/chemse/bjx042] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Since starch is a significant part of human diet, its oral detection would be highly beneficial. This study was designed to determine whether starch or its degradation products can be tasted and what factors influence its perception. Subjects were asked 1) to taste 8% raw and cooked starch samples for 5, 15, and 35 s and rate perceived intensities of sweetness and "other" taste (i.e., other than sweet), 2) to donate saliva to obtain salivary flow rate (mg/s) and salivary α-amylase activity (per mg saliva), and 3) to fill out a carbohydrate consumption survey. Subsequently, in vitro hydrolysis of starch was performed; saliva was collected from 5 subjects with low and high amylase activities and reacted with 8% raw and cooked starch at 2, 15, and 30 s. Hydrolysis products were then quantified using a High performance liquid chromatography. The results showed cooking increased the digestibility of starch such that the amount of hydrolysis products increased with reaction time. However, cooking did not influence taste ratings, nor were they influenced by tasting time. Subjects' salivary amylase activities were associated with the efficacy of their saliva to degrade starch, in particular cooked starch, and thus the amount of maltooligosaccharide products generated. Effective α-amylase activity [i.e. α-amylase activity (per mg saliva) × salivary flow rate (mg/s)] and carbohydrate consumption score (i.e. consumption frequency × number of servings) were also independently associated with sensory taste ratings. Human perception of starch is undoubtedly complex as shown in this study; the data herein point to the potential roles of salivary α-amylase activity and carbohydrate consumption in the perception of cooked starch.
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Affiliation(s)
- Trina J Lapis
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, USA
| | - Michael H Penner
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, USA
| | - Amy S Balto
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, USA
| | - Juyun Lim
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, USA
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Evidence supporting oral sensitivity to complex carbohydrates independent of sweet taste sensitivity in humans. PLoS One 2017; 12:e0188784. [PMID: 29281655 PMCID: PMC5744938 DOI: 10.1371/journal.pone.0188784] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 11/13/2017] [Indexed: 12/31/2022] Open
Abstract
Compared to simple sugars, complex carbohydrates have been assumed invisible to taste. However, two recent studies proposed that there may be a perceivable taste quality elicited by complex carbohydrates independent of sweet taste. There is precedent with behavioural studies demonstrating that rats are very attracted to complex carbohydrates, and that complex carbohydrates are preferred to simple sugars at low concentrations. This suggests that rats may have independent taste sensors for simple sugars and complex carbohydrates. The aim of this paper is to investigate oral sensitivities of two different classes of complex carbohydrates (a soluble digestible and a soluble non-digestible complex carbohydrate), and to compare these to other caloric and non-nutritive sweeteners in addition to the prototypical tastes using two commonly used psychophysical measures. There were strong correlations between the detection thresholds and mean intensity ratings for complex carbohydrates (maltodextrin, oligofructose) (r = 0.94, P < 0.001). There were no significant correlations between the detection thresholds of the complex carbohydrates (maltodextrin, oligofructose) and the sweeteners (glucose, fructose, sucralose, Rebaudioside A, erythritol) (all P > 0.05). However, moderate correlations were observed between perceived intensities of complex carbohydrates and sweeteners (r = 0.48–0.61, P < 0.05). These data provide evidence that complex carbohydrates can be sensed in the oral cavity over a range of concentrations independent of sweet taste sensitivity at low concentrations, but with partial overlap with sweet taste intensity at higher concentrations.
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Blonde GD, Spector AC. An Examination of the Role of L-Glutamate and Inosine 5'-Monophosphate in Hedonic Taste-Guided Behavior by Mice Lacking the T1R1 + T1R3 Receptor. Chem Senses 2017; 42:393-404. [PMID: 28334294 DOI: 10.1093/chemse/bjx015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The heterodimeric T1R1 + T1R3 receptor is considered critical for normal signaling of L-glutamate and 5'-ribonucleotides in the oral cavity. However, some taste-guided responsiveness remains in mice lacking one subunit of the receptor, suggesting that other receptors are sufficient to support some behaviors. Here, mice lacking both receptor subunits (KO) and wild-type (WT, both n = 13) mice were tested in a battery of behavioral tests. Mice were trained and tested in gustometers with a concentration series of Maltrin-580, a maltodextrin, in a brief-access test (10-s trials) as a positive control. Similar tests followed with monosodium glutamate (MSG) with and without the ribonucleotide inosine 5'-monophosphate (IMP), but always in the presence of the epithelial sodium channel blocker amiloride (A). Brief-access tests were repeated following short-term (30-min) and long-term (48-h) exposures to MSG + A + IMP and were also conducted with sodium gluconate replacing MSG. Finally, progressive ratio tests were conducted with Maltrin-580 or MSG + A + IMP, to assess appetitive behavior while minimizing satiation. Overall, MSG generated little concentration-dependent responding in either food-restricted WT or KO mice, even in combination with IMP. However, KO mice licked less to the amino acid stimuli, a measure of consummatory behavior in the brief-access tests. In contrast, both groups initiated a similar number of trials and had a similar breakpoint in the progressive ratio task, both measures of appetitive (approach) behavior. Collectively, these results suggest that while the T1R1 + T1R3 receptor is necessary for consummatory responding to MSG (+IMP), other receptors are sufficient to maintain appetitive responding to this "umami" stimulus complex in food-restricted mice.
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Affiliation(s)
- Ginger D Blonde
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL, USA
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL, USA
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Pullicin AJ, Penner MH, Lim J. Human taste detection of glucose oligomers with low degree of polymerization. PLoS One 2017; 12:e0183008. [PMID: 28850567 PMCID: PMC5574539 DOI: 10.1371/journal.pone.0183008] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 07/27/2017] [Indexed: 12/14/2022] Open
Abstract
Studies have reported that some animals, including humans, can taste mixtures of glucose oligomers (i.e., maltooligosaccharides, MOS) and that their detection is independent of the known T1R2/T1R3 sweet taste receptor. In an effort to understand potential mechanisms underlying the taste perception of glucose oligomers in humans, this study was designed to investigate: 1) the variability of taste sensitivity to MOS with low degree-of-polymerization (DP), and 2) the potential role of hT1R2/T1R3 in the MOS taste detection. To address these objectives, a series of food grade, narrow-DP-range MOS were first prepared (DP 3, 3–4, 5–6, and 6–7) by fractionating disperse saccharide mixtures. Subjects were then asked to discriminate these MOS stimuli as well as glucose (DP 1) and maltose (DP 2) from blanks after the stimuli were swabbed on the tongue. All stimuli were presented at 75 mM with and without a sweet taste inhibitor (lactisole). An α-glucosidase inhibitor (acarbose) was added to all test stimuli to prevent oral digestion of glucose oligomers. Results showed that all six stimuli were detected with similar discriminability in normal tasting conditions. When the sweet receptor was inhibited, DP 1, 2, and 3 were not discriminated from blanks. In contrast, three higher-DP paired MOS stimuli (DP 3–4, 5–6, and 6–7) were discriminated from blanks at a similar degree. Overall, these results support the presence of a sweet-independent taste perception mechanism that is stimulated by MOS greater than three units.
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Affiliation(s)
- Alexa J. Pullicin
- Department of Food Science & Technology, Oregon State University, Corvallis, Oregon, United States of America
| | - Michael H. Penner
- Department of Food Science & Technology, Oregon State University, Corvallis, Oregon, United States of America
| | - Juyun Lim
- Department of Food Science & Technology, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
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Smith KR, Spector AC. Detection of maltodextrin and its discrimination from sucrose are independent of the T1R2 + T1R3 heterodimer. Am J Physiol Regul Integr Comp Physiol 2017; 313:R450-R462. [PMID: 28768658 DOI: 10.1152/ajpregu.00049.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 07/11/2017] [Accepted: 07/24/2017] [Indexed: 12/25/2022]
Abstract
Maltodextrins, such as Maltrin and Polycose, are glucose polymer mixtures of varying chain lengths that are palatable to rodents. Although glucose and other sugars activate the T1R2 + T1R3 "sweet" taste receptor, recent evidence from T1R2- or T1R3-knockout (KO) mice suggests that maltodextrins, despite their glucose polymer composition, activate a separate receptor mechanism to generate a taste percept qualitatively distinguishable from that of sweeteners. However, explicit discrimination of maltodextrins from prototypical sweeteners has not yet been psychophysically tested in any murine model. Therefore, mice lacking T1R2 + T1R3 and wild-type controls were tested in a two-response taste discrimination task to determine whether maltodextrins are 1) detectable when both receptor subunits are absent and 2) perceptually distinct from that of sucrose irrespective of viscosity, intensity, and hedonics. Most KO mice displayed similar Polycose sensitivity as controls. However, some KO mice were only sensitive to the higher Polycose concentrations, implicating potential allelic variation in the putative polysaccharide receptor or downstream pathways unmasked by the absence of T1R2 + T1R3. Varied Maltrin and sucrose concentrations of approximately matched viscosities were then presented to render the oral somatosensory features, intensity, and hedonic value of the solutions irrelevant. Although both genotypes competently discriminated Maltrin from sucrose, performance was apparently driven by the different orosensory percepts of the two stimuli in control mice and the presence of a Maltrin but not sucrose orosensory cue in KO mice. These data support the proposed presence of an orosensory receptor mechanism that gives rise to a qualitatively distinguishable sensation from that of sucrose.
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Affiliation(s)
- Kimberly R Smith
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
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Sclafani A, Vural AS, Ackroff K. CAST/EiJ and C57BL/6J Mice Differ in Their Oral and Postoral Attraction to Glucose and Fructose. Chem Senses 2017; 42:259-267. [PMID: 28158517 DOI: 10.1093/chemse/bjx003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A recent study indicated that CAST/EiJ and C57BL/6J mice differ in their taste preferences for maltodextrin but display similar sucrose preferences. The present study revealed strain differences in preferences for the constituent sugars of sucrose. Whereas B6 mice preferred 8% glucose to 8% fructose in 2-day tests, the CAST mice preferred fructose to glucose. These preferences emerged with repeated testing which suggested post-oral influences. In a second experiment, 2-day choice tests were conducted with the sugars versus a sucralose + saccharin (SS) mixture which is highly preferred in brief access tests. B6 mice strongly preferred glucose but not fructose to the non-nutritive SS whereas CAST mice preferred SS to both glucose and fructose even when food restricted. This implied that CAST mice are insensitive to the postoral appetite stimulating actions of the 2 sugars. A third experiment revealed, however, that intragastric glucose and fructose infusions conditioned significant but mild flavor preferences in CAST mice, whereas in B6 mice glucose conditioned a robust preference but fructose was ineffective. Thus, unlike other mouse strains and rats, glucose is not more reinforcing than fructose in CAST mice. Their oral preference for fructose over glucose may be related to a subsensitive maltodextrin receptor or glucose-specific receptor which is stimulated by glucose but not fructose. The failure of CAST mice to prefer glucose to a non-nutritive sweetener distinguishes this strain from other mouse strains and rats.
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Affiliation(s)
- Anthony Sclafani
- Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
| | - Austin S Vural
- Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
| | - Karen Ackroff
- Department of Psychology, Brooklyn College of the City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
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Flavor preferences conditioned by nutritive and non-nutritive sweeteners in mice. Physiol Behav 2017; 173:188-199. [PMID: 28192132 DOI: 10.1016/j.physbeh.2017.02.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 01/18/2017] [Indexed: 01/08/2023]
Abstract
Recent studies suggest that preferences are conditioned by nutritive (sucrose) but not by non-nutritive (sucralose) sweeteners in mice. Here we compared the effectiveness of nutritive and non-nutritive sweeteners to condition flavor preferences in three mouse strains. Isopreferred sucrose and sucralose solutions both conditioned flavor preferences in C57BL/6J (B6) mice but sucrose was more effective, consistent with its post-oral appetition action. Subsequent experiments compared flavor conditioning by fructose, which has no post-oral appetition effect in B6 mice, and a sucralose+saccharin mixture (SS) which is highly preferred to fructose in 24-h choice tests. Both sweeteners conditioned flavor preferences but fructose induced stronger preferences than SS. Training B6 mice to drink a flavored SS solution paired with intragastric fructose infusions did not enhance the SS-conditioned preference. Thus, the post-oral nutritive actions of fructose do not explain the sugar's stronger preference conditioning effect. Training B6 mice to drink a flavored fructose solution containing SS did not reduce the sugar-conditioned preference, indicating that SS does not have an off-taste that attenuates conditioning. Although B6 mice strongly preferred flavored SS to flavored fructose in a direct choice test, they preferred the fructose-paired flavor to the SS-paired flavor when these were presented in water. Fructose conditioned a stronger flavor preference than an isopreferred saccharin solution, indicating that sucralose is not responsible for the limited SS conditioning actions. SS is highly preferred by FVB/NJ and CAST/EiJ inbred mice, yet conditioned only weak flavor preferences. It is unclear why highly or equally preferred non-nutritive sweeteners condition weaker preferences than fructose, when all stimulate the same T1r2/T1r3 sweet receptor. Recent findings support the existence of non-T1r2/T1r3 glucose taste sensors; however, there is no evidence for receptors that respond to fructose but not to non-nutritive sweeteners.
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Glendinning JI, Frim YG, Hochman A, Lubitz GS, Basile AJ, Sclafani A. Glucose elicits cephalic-phase insulin release in mice by activating K ATP channels in taste cells. Am J Physiol Regul Integr Comp Physiol 2017; 312:R597-R610. [PMID: 28148491 DOI: 10.1152/ajpregu.00433.2016] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 01/17/2017] [Accepted: 01/17/2017] [Indexed: 12/25/2022]
Abstract
The taste of sugar elicits cephalic-phase insulin release (CPIR), which limits the rise in blood glucose associated with meals. Little is known, however, about the gustatory mechanisms that trigger CPIR. We asked whether oral stimulation with any of the following taste stimuli elicited CPIR in mice: glucose, sucrose, maltose, fructose, Polycose, saccharin, sucralose, AceK, SC45647, or a nonmetabolizable sugar analog. The only taste stimuli that elicited CPIR were glucose and the glucose-containing saccharides (sucrose, maltose, Polycose). When we mixed an α-glucosidase inhibitor (acarbose) with the latter three saccharides, the mice no longer exhibited CPIR. This revealed that the carbohydrates were hydrolyzed in the mouth, and that the liberated glucose triggered CPIR. We also found that increasing the intensity or duration of oral glucose stimulation caused a corresponding increase in CPIR magnitude. To identify the components of the glucose-specific taste-signaling pathway, we examined the necessity of Calhm1, P2X2+P2X3, SGLT1, and Sur1. Among these proteins, only Sur1 was necessary for CPIR. Sur1 was not necessary, however, for taste-mediated attraction to sugars. Given that Sur1 is a subunit of the ATP-sensitive K+ channel (KATP) channel and that this channel functions as a part of a glucose-sensing pathway in pancreatic β-cells, we asked whether the KATP channel serves an analogous role in taste cells. We discovered that oral stimulation with drugs known to increase (glyburide) or decrease (diazoxide) KATP signaling produced corresponding changes in glucose-stimulated CPIR. We propose that the KATP channel is part of a novel signaling pathway in taste cells that mediates glucose-induced CPIR.
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Affiliation(s)
- John I Glendinning
- Department of Biology, Barnard College, Columbia University, New York, New York;
| | - Yonina G Frim
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Ayelet Hochman
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Gabrielle S Lubitz
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Anthony J Basile
- Department of Biology, Barnard College, Columbia University, New York, New York.,Institute of Human Nutrition, Columbia University, New York, New York; and
| | - Anthony Sclafani
- Department of Psychology, Brooklyn College of City University of New York, Brooklyn, New York
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Behavioral evidence that select carbohydrate stimuli activate T1R-independent receptor mechanisms. Appetite 2016; 122:26-31. [PMID: 28034739 DOI: 10.1016/j.appet.2016.12.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 12/22/2016] [Accepted: 12/22/2016] [Indexed: 01/21/2023]
Abstract
Three decades ago Tony Sclafani proposed the existence of a polysaccharide taste quality that was distinguishable from the taste generated by common sweeteners and that it was mediated by a separate receptor mechanism. Since that time, evidence has accumulated, including psychophysical studies conducted in our laboratory, buttressing this hypothesis. The use of knockout (KO) mice that lack functional T1R2 + T1R3 heterodimers, the principal taste receptor for sugars and other sweeteners, have been especially informative in this regard. Such KO mice display severely diminished electrophysiological and behavioral responsiveness to sugars, artificial sweeteners, and some amino acids, yet display only slightly impaired concentration-dependent responsiveness to a representative polysaccharide, Polycose. Moreover, although results from gene deletion experiments in the literature provide strong support for the primacy of the T1R2 + T1R3 heterodimer in the taste transduction of sugars and other sweeteners, there is also growing evidence suggesting that there may be T1R-independent receptor mechanism(s) activated by select sugars, especially glucose. The output of these latter receptor mechanisms appears to be channeled into brain circuits subserving various taste functions such as cephalic phase responses and ingestive motivation. This paper highlights some of the findings from our laboratory and others that lend support for this view, while emphasizing the importance of considering the multidimensional nature of taste function in the interpretation of outcomes from experiments involving manipulations of the gustatory system.
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40
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Lapis TJ, Penner MH, Lim J. Humans Can Taste Glucose Oligomers Independent of the hT1R2/hT1R3 Sweet Taste Receptor. Chem Senses 2016; 41:755-762. [PMID: 27553043 DOI: 10.1093/chemse/bjw088] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
It is widely accepted that humans can taste mono- and disaccharides as sweet substances, but they cannot taste longer chain oligo- and polysaccharides. From the evolutionary standpoint, the ability to taste starch or its oligomeric hydrolysis products would be highly adaptive, given their nutritional value. Here, we report that humans can taste glucose oligomer preparations (average degree of polymerization 7 and 14) without any other sensorial cues. The same human subjects could not taste the corresponding glucose polymer preparation (average degree of polymerization 44). When the sweet taste receptor was blocked by lactisole, a known sweet inhibitor, subjects could not detect sweet substances (glucose, maltose, and sucralose), but they could still detect the glucose oligomers. This suggests that glucose oligomer detection is independent of the hT1R2/hT1R3 sweet taste receptor. Human subjects described the taste of glucose oligomers as "starchy," while they describe sugars as "sweet." The dose-response function of glucose oligomer was also found to be indistinguishable from that of glucose on a molar basis.
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Affiliation(s)
- Trina J Lapis
- Department of Food Science and Technology, Oregon State University , Corvallis, OR 97331 , USA
| | - Michael H Penner
- Department of Food Science and Technology, Oregon State University , Corvallis, OR 97331 , USA
| | - Juyun Lim
- Department of Food Science and Technology, Oregon State University , Corvallis, OR 97331 , USA
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41
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Ackroff K, Sclafani A. Maltodextrin and sucrose preferences in sweet-sensitive (C57BL/6J) and subsensitive (129P3/J) mice revisited. Physiol Behav 2016; 165:286-90. [PMID: 27526998 DOI: 10.1016/j.physbeh.2016.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 07/15/2016] [Accepted: 08/11/2016] [Indexed: 12/18/2022]
Abstract
Mice are attracted to the tastes of sugar and maltodextrin solutions. Sugar taste is mediated by the T1R2/T1R3 sweet taste receptor, while maltodextrin taste is dependent upon a different as yet unidentified receptor. In a prior study sweet-sensitive C57BL/6J (B6) mice displayed similar preferences for sucrose and maltodextrin solutions in 24-h saccharide vs. water choice tests that exceeded those of sweet-subsensitive 129P3/J (129) mice. In a subsequent experiment reported here, sucrose and maltodextrin (Polycose) preference and acceptance were compared in the two strains in saccharide vs. saccharide choice tests with isocaloric concentrations (0.5-32%). The 129 mice displayed significantly greater maltodextrin preferences than B6 mice at mid-range concentrations (2-8%), while the mice displayed an opposite preference profile at the highest concentration (32%). As in prior studies, 129 mice consumed less total saccharide than B6 mice at lower concentrations. These findings show that the conclusions reached from tastant vs. water tests may differ from those pitting one tastant against another. The increased sucrose preference and intake of B6 mice, relative to 129 mice, is consistent with their sweet-sensitive phenotype.
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Affiliation(s)
- Karen Ackroff
- Department of Psychology, Brooklyn College and the Graduate School, The City University of New York, Brooklyn, NY 11210, USA.
| | - Anthony Sclafani
- Department of Psychology, Brooklyn College and the Graduate School, The City University of New York, Brooklyn, NY 11210, USA
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Schier LA, Spector AC. Post-oral sugar detection rapidly and chemospecifically modulates taste-guided behavior. Am J Physiol Regul Integr Comp Physiol 2016; 311:R742-R755. [PMID: 27511277 DOI: 10.1152/ajpregu.00155.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 08/03/2016] [Indexed: 12/31/2022]
Abstract
Several recent studies have shown that post-oral sugar sensing rapidly stimulates ingestion. Here, we explored the specificity with which early-phase post-oral sugar sensing influenced ingestive motivation. In experiment 1, rats were trained to associate the consumption of 0.3 M sucrose with injections of LiCl (3.0 meq/kg ip, conditioned taste aversion) or given equivalent exposures to the stimuli, but in an unpaired fashion. Then, all rats were subjected to two brief-access tests to assess appetitive and consummatory responses to the taste properties of sucrose (0.01-1.0 M), 0.12 M NaCl, and dH2O (in 10-s trials in randomized blocks). Intraduodenal infusions of either 0.3 M sucrose or equiosmolar 0.15 M NaCl (3.0 ml) were administered, beginning just before each test. For unpaired rats, intraduodenal sucrose specifically enhanced licking for 0.03-1.0 M sucrose, with no effect on trial initiation, relative to intraduodenal NaCl. Rats with an aversion to sucrose suppressed licking responses to sucrose in a concentration-dependent manner, as expected, but the intraduodenal sucrose preload did not appear to further influence licking responses; instead, intraduodenal sucrose attenuated trial initiation. Using a serial taste reactivity (TR) paradigm, however, experiment 2 demonstrated that intraduodenal sucrose preloads suppressed ingestive oromotor responses to intraorally delivered sucrose in rats with a sucrose aversion. Finally, experiment 3 showed that intraduodenal sucrose preloads enhanced preferential licking to some representative tastants tested (sucrose, Polycose, and Intralipid), but not others (NaCl, quinine). Together, the results suggest that the early phase-reinforcing efficacy of post-oral sugar is dependent on the sensory and motivational properties of the ingesta.
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Affiliation(s)
- Lindsey A Schier
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
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Boersma GJ, Treesukosol Y, Cordner ZA, Kastelein A, Choi P, Moran TH, Tamashiro KL. Exposure to activity-based anorexia impairs contextual learning in weight-restored rats without affecting spatial learning, taste, anxiety, or dietary-fat preference. Int J Eat Disord 2016; 49:167-79. [PMID: 26711541 PMCID: PMC4777973 DOI: 10.1002/eat.22489] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 09/30/2015] [Accepted: 11/13/2015] [Indexed: 02/02/2023]
Abstract
UNLABELLED Relapse rates are high amongst cases of anorexia nervosa (AN) suggesting that some alterations induced by AN may remain after weight restoration. OBJECTIVE To study the consequences of AN without confounds of environmental variability, a rodent model of activity-based anorexia (ABA) can be employed. We hypothesized that exposure to ABA during adolescence may have long-term consequences in taste function, cognition, and anxiety-like behavior after weight restoration. METHODS To test this hypothesis, we exposed adolescent female rats to ABA (1.5 h food access, combined with voluntary running wheel access) and compared their behavior to that of control rats after weight restoration was achieved. The rats were tested for learning/memory, anxiety, food preference, and taste in a set of behavioral tests performed during the light period. RESULTS Our data show that ABA exposure leads to reduced performance during the novel object recognition task, a test for contextual learning, without altering performance in the novel place recognition task or the Barnes maze, both tasks that test spatial learning. Furthermore, we do not observe alterations in unconditioned lick responses to sucrose nor quinine (described by humans as "sweet" and "bitter," respectively). Nor Do we find alterations in anxiety-like behavior during an elevated plus maze or an open field test. Finally, preference for a diet high in fat is not altered. DISCUSSION Overall, our data suggest that ABA exposure during adolescence impairs contextual learning in adulthood without altering spatial leaning, taste, anxiety, or fat preference.
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Affiliation(s)
- Gretha J. Boersma
- Department of Psychiatry and Behavioral Sciences School of Medicine; Johns Hopkins University; Baltimore Maryland
| | - Yada Treesukosol
- Department of Psychiatry and Behavioral Sciences School of Medicine; Johns Hopkins University; Baltimore Maryland
| | - Zachary A. Cordner
- Department of Psychiatry and Behavioral Sciences School of Medicine; Johns Hopkins University; Baltimore Maryland
| | - Anneke Kastelein
- Department of Psychiatry and Behavioral Sciences School of Medicine; Johns Hopkins University; Baltimore Maryland
| | - Pique Choi
- Department of Psychiatry and Behavioral Sciences School of Medicine; Johns Hopkins University; Baltimore Maryland
| | - Timothy H. Moran
- Department of Psychiatry and Behavioral Sciences School of Medicine; Johns Hopkins University; Baltimore Maryland
| | - Kellie L. Tamashiro
- Department of Psychiatry and Behavioral Sciences School of Medicine; Johns Hopkins University; Baltimore Maryland
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44
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Spector AC. Behavioral analyses of taste function and ingestion in rodent models. Physiol Behav 2015; 152:516-26. [PMID: 25892670 PMCID: PMC4608852 DOI: 10.1016/j.physbeh.2015.04.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/09/2015] [Indexed: 12/31/2022]
Abstract
In 1975, at the start of my junior year in college, I took a course on experimental methods in psychology from Dr. James C. Smith, when he was a Visiting Professor at Penn State University. That experience set me on the professional path of studying the neural bases of taste function and ingestion on which I remain to this day. Along the way, I did my graduate work at Florida State University under the tutelage of Jim, I did my postdoctoral training at the University of Pennsylvania under the supervision of Harvey Grill, and I also worked closely with Ralph Norgren, who was at the Penn State Medical College. This article briefly summarizes some of the lessons I learned from my mentors and highlights a few key research findings arising from my privilege of working with gifted students and postdocs. After close to 40 years of being a student of the gustatory system and ingestive behavior, it is still with the greatest conviction that I believe rigorous analysis of behavior is indispensable to any effort seeking to understand brain function.
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Affiliation(s)
- Alan C Spector
- Department of Psychology, Florida State University, Tallahassee, FL, USA; Program in Neuroscience, Florida State University, Tallahassee, FL, USA.
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45
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Poole RL, Aleman TR, Ellis HT, Tordoff MG. Maltodextrin Acceptance and Preference in Eight Mouse Strains. Chem Senses 2015; 41:45-52. [PMID: 26464499 DOI: 10.1093/chemse/bjv056] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Rodents are strongly attracted to the taste(s) of maltodextrins. A first step toward discovery of the underlying genes involves identifying phenotypic differences among inbred strains of mice. To do this, we used 5-s brief-access tests and 48-h 2-bottle choice tests to survey the avidity for the maltodextrin, Maltrin M040, of mice from 8 inbred strains (129S1/SvImJ, A/J, CAST/EiJ, C57BL/6J, NOD/ShiLTJ, NZO/HlLtJ, PWK/PhJ, and WSB/EiJ). In brief-access tests, the CAST and PWK strains licked significantly less maltodextrin than equivalent concentrations of sucrose, whereas the other strains generally licked the 2 carbohydrates equally. Similarly, in 2-bottle choice tests, the CAST and PWK strains drank less 4% maltodextrin than 4% sucrose, whereas the other strains had similar intakes of these 2 solutions; the CAST and PWK strains did not differ from the C57, NOD, or NZO strains in 4% sucrose intake. In sum, we have identified strain variation in maltodextrin perception that is distinct from variation in sucrose perception. The phenotypic variation characterized here will aid in identifying genes responsible for maltodextrin acceptance. Our results identify C57 × PWK mice or NZO × CAST mice as informative crosses to produce segregating hybrids that will expose quantitative trait loci underlying maltodextrin acceptance and preference.
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Affiliation(s)
- Rachel L Poole
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Tiffany R Aleman
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Hillary T Ellis
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Michael G Tordoff
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
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46
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Cheled-Shoval SL, Druyan S, Uni Z. Bitter, sweet and umami taste receptors and downstream signaling effectors: Expression in embryonic and growing chicken gastrointestinal tract. Poult Sci 2015; 94:1928-41. [DOI: 10.3382/ps/pev152] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2015] [Indexed: 12/12/2022] Open
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47
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Glendinning JI, Stano S, Holter M, Azenkot T, Goldman O, Margolskee RF, Vasselli JR, Sclafani A. Sugar-induced cephalic-phase insulin release is mediated by a T1r2+T1r3-independent taste transduction pathway in mice. Am J Physiol Regul Integr Comp Physiol 2015; 309:R552-60. [PMID: 26157055 PMCID: PMC4591378 DOI: 10.1152/ajpregu.00056.2015] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 07/06/2015] [Indexed: 12/11/2022]
Abstract
Sensory stimulation from foods elicits cephalic phase responses, which facilitate digestion and nutrient assimilation. One such response, cephalic-phase insulin release (CPIR), enhances glucose tolerance. Little is known about the chemosensory mechanisms that activate CPIR. We studied the contribution of the sweet taste receptor (T1r2+T1r3) to sugar-induced CPIR in C57BL/6 (B6) and T1r3 knockout (KO) mice. First, we measured insulin release and glucose tolerance following oral (i.e., normal ingestion) or intragastric (IG) administration of 2.8 M glucose. Both groups of mice exhibited a CPIR following oral but not IG administration, and this CPIR improved glucose tolerance. Second, we examined the specificity of CPIR. Both mouse groups exhibited a CPIR following oral administration of 1 M glucose and 1 M sucrose but not 1 M fructose or water alone. Third, we studied behavioral attraction to the same three sugar solutions in short-term acceptability tests. B6 mice licked more avidly for the sugar solutions than for water, whereas T1r3 KO mice licked no more for the sugar solutions than for water. Finally, we examined chorda tympani (CT) nerve responses to each of the sugars. Both mouse groups exhibited CT nerve responses to the sugars, although those of B6 mice were stronger. We propose that mice possess two taste transduction pathways for sugars. One mediates behavioral attraction to sugars and requires an intact T1r2+T1r3. The other mediates CPIR but does not require an intact T1r2+T1r3. If the latter taste transduction pathway exists in humans, it should provide opportunities for the development of new treatments for controlling blood sugar.
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Affiliation(s)
- John I Glendinning
- Department of Biology, Barnard College, Columbia University, New York, New York;
| | - Sarah Stano
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Marlena Holter
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Tali Azenkot
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Olivia Goldman
- Department of Biology, Barnard College, Columbia University, New York, New York
| | | | - Joseph R Vasselli
- Obesity Research Center, Department of Medicine, Columbia University, New York, New York; and
| | - Anthony Sclafani
- Department of Psychology, Brooklyn College of City University of New York, Brooklyn, New York
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Roebber JK, Izenwasser S, Chaudhari N. Cocaine decreases saccharin preference without altering sweet taste sensitivity. Pharmacol Biochem Behav 2015; 133:18-24. [PMID: 25812471 PMCID: PMC4430401 DOI: 10.1016/j.pbb.2015.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 03/10/2015] [Accepted: 03/16/2015] [Indexed: 10/23/2022]
Abstract
In rodents, saccharin consumption is suppressed when the sweet taste stimulus is paired with moderate doses of cocaine. Several hypotheses have been used to explain the seemingly contradictory effect of decreased consumption of a normally preferred substance following a highly rewarding drug. A common theme across these hypotheses is that saccharin is interpreted as less rewarding after cocaine pairing. We considered the alternative possibility that suppression is caused not by a change in reward circuitry, but rather by a change in taste detection, for instance by altering the afferent taste response and decreasing sensitivity to sweet taste stimuli. To evaluate this possibility, we measured saccharin taste sensitivity of mice before and after a standard cocaine-pairing paradigm. We measured taste sensitivity using a brief-access lickometer equipped with multiple concentrations of saccharin solution and established concentration-response curves before and after saccharin-cocaine pairing. Our results indicate that the EC50 for saccharin was unaltered following pairing. Instead, the avidity of licking saccharin, an indicator of motivation, was depressed. Latency to first-lick, a negative indicator of motivation, was also dramatically increased. Thus, our findings are consistent with the interpretation that saccharin-cocaine pairing results in devaluing of the sweet taste reward.
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Affiliation(s)
- Jennifer K Roebber
- Graduate Program in Neurosciences, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Sari Izenwasser
- Graduate Program in Neurosciences, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Nirupa Chaudhari
- Graduate Program in Neurosciences, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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49
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Sclafani A, Ackroff K. Flavor preference conditioning by different sugars in sweet ageusic Trpm5 knockout mice. Physiol Behav 2014; 140:156-63. [PMID: 25497884 DOI: 10.1016/j.physbeh.2014.12.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/10/2014] [Accepted: 12/11/2014] [Indexed: 01/05/2023]
Abstract
Knockout (KO) mice missing the taste signaling protein Trpm5 have greatly attenuated sweetener preferences but develop strong preferences for glucose in 24-h tests, which is attributed to post-oral sugar conditioning. Trpm5 KO mice express mild preferences for galactose but no preferences for fructose in 24-h tests, which suggests that these sugars differ in their post-oral reinforcing effects. Here we investigated sugar-conditioned flavor preferences in Trpm5 KO and C57BL/6J wildtype (B6) mice. The mice were trained to consume a flavored (CS+, e.g. grape) 8% sugar solution and flavored (CS-, e.g., cherry) water on alternating days followed by two-bottle choice tests with CS+ vs. CS- flavors in water and with unflavored sugar vs. water. The KO mice displayed strong preferences (>80%) for the CS+ glucose and CS+ galactose but not for the CS+ fructose flavor. They also preferred glucose and galactose, but not fructose to water. In contrast, the B6 mice preferred all three CS+ flavors to the CS- flavor, and all three sugars to water. In tests with the non-metabolizable sugar α-methyl-d-glucopyranoside (MDG), the KO and B6 mice preferred 8% MDG to water but did not prefer the CS+ 8% MDG to CS-. However, they preferred a CS+ flavor mixed with 4% MDG over the CS- flavor. Trpm5 KO mice also preferred galactose and MDG to fructose in direct choice tests. The Trpm5 KO data indicate that glucose and, to a lesser extent, galactose and MDG have post-oral reinforcing actions that stimulate intake and preference while fructose has a much weaker effect. The CS+ flavor and sugar preferences of B6 mice may be mediated by the sweet taste and/or post-oral actions of the various sugars. Glucose, galactose, and MDG, but not fructose, are ligands for the sodium-glucose transporter 1 (SGLT1) which is implicated in post-oral sugar conditioning in B6 mice.
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Affiliation(s)
- Anthony Sclafani
- Brooklyn College and the Graduate School, City University of New York, Brooklyn, NY 11210, USA.
| | - Karen Ackroff
- Brooklyn College and the Graduate School, City University of New York, Brooklyn, NY 11210, USA
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50
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Tordoff MG, Aleman TR, McCaughey SA. Heightened avidity for trisodium pyrophosphate in mice lacking Tas1r3. Chem Senses 2014; 40:53-9. [PMID: 25452580 DOI: 10.1093/chemse/bju059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Laboratory rats and mice prefer some concentrations of tri- and tetrasodium pyrophosphate (Na3HP2O7 and Na4P2O7) to water, but how they detect pyrophosphates is unknown. Here, we assessed whether T1R3 is involved. We found that relative to wild-type littermate controls, Tas1r3 knockout mice had stronger preferences for 5.6-56mM Na3HP2O7 in 2-bottle choice tests, and they licked more 17.8-56mM Na3HP2O7 in brief-access tests. We hypothesize that pyrophosphate taste in the intact mouse involves 2 receptors: T1R3 to produce a hedonically negative signal and an unknown G protein-coupled receptor to produce a hedonically positive signal; in Tas1r3 knockout mice, the hedonically negative signal produced by T1R3 is absent, leading to a heightened avidity for pyrophosphate.
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Affiliation(s)
- Michael G Tordoff
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA and
| | - Tiffany R Aleman
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA and
| | - Stuart A McCaughey
- Center for Medical Education, IUSM-Muncie at Ball State University, 221 N. Celia Avenue, MT 201, Muncie, IN 47306, USA
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