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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: 0] [Impact Index Per Article: 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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Oral stimulation with maltodextrin: Effect on cephalic phase insulin release. Appetite 2023; 183:106464. [PMID: 36682624 DOI: 10.1016/j.appet.2023.106464] [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: 10/19/2022] [Revised: 01/11/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023]
Abstract
Cephalic phase insulin release (CPIR) occurs following sensory stimulation with food-related stimuli, and has been shown to limit postabsorptive hyperglycemia. While the specific stimuli that elicit CPIR in humans have not been clearly defined, previous research points to sugars as having potential importance. Maltodextrins are a starch-derived food ingredient commonly found in a variety of processed food products. When consumed, salivary α-amylase rapidly cleaves its component saccharides into smaller units, leading to the production of sugars in the mouth. Here, we investigated whether humans elicit CPIR after tasting but not swallowing maltodextrin, and whether the degree of CPIR exhibited is affected by individuals' salivary α-amylase activity. We found that a gelatin-based stimulus containing 22% w/v maltodextrin elicited CPIR in healthy individuals (N = 22) following a modified sham-feeding protocol using both insulin and c-peptide as indices of the response. However, the degree of CPIR measured did not differ across three groupings (low, medium, or high) of effective α-amylase activity by either index. In a follow-up experiment, a subset of participants (N = 14) underwent the same protocol using a gelatin stimulus without maltodextrin, and no observable CPIR ensued. These findings suggest that oral stimulation with maltodextrin elicits CPIR in humans, but that individual differences in effective salivary α-amylase activity may not necessarily be predictive of the degree of CPIR.
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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: 1] [Impact Index Per Article: 1.0] [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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Andrewson TS, Martin LE, Lim J, Penner MH. Chromatographic fractionation of food-grade oligosaccharides: Recognizing and avoiding sensory-relevant impurities. Food Chem 2023; 401:134071. [PMID: 36115234 PMCID: PMC9945451 DOI: 10.1016/j.foodchem.2022.134071] [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: 04/18/2022] [Revised: 08/25/2022] [Accepted: 08/28/2022] [Indexed: 02/08/2023]
Abstract
Flash chromatography utilizing microcrystalline cellulose (MCC) stationary phases and aqueous ethanol mobile phases have shown promise for the production of food-grade oligosaccharides. The current work extends the scope of these systems by demonstrating their use for the production of food-grade maltooligosaccharide preparations enriched in high degree of polymerization (DP) components. Furthermore, it is shown herein that caution must be exercised when using these MCC-based chromatographic systems in order to avoid sensory-relevant contamination of the final oligosaccharide preparations. Such contamination, most notably off-taste, is shown to arise from impurities common to commercially available MCC that manifest under certain chromatographic scenarios. A mitigation strategy based on washing the stationary phase with appropriate aqueous-ethanol solutions (i.e., accounting for the entire mobile phase concentration range) prior to oligosaccharide fractionation is presented as a means by which to avoid contamination.
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Affiliation(s)
- Toren S Andrewson
- Department of Food Science and Technology, Oregon State University, Corvallis, OR, USA
| | - Laura E Martin
- 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.
| | - Michael H Penner
- Department of Food Science and Technology, Oregon State University, Corvallis, OR, USA.
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Damani S, Penner MH, Lim J. Taste perception of oligosaccharides derived from pullulan. Chem Senses 2023; 48:bjad031. [PMID: 37589411 PMCID: PMC10473447 DOI: 10.1093/chemse/bjad031] [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: 03/31/2023] [Indexed: 08/18/2023] Open
Abstract
Recent studies indicate that humans can taste starch hydrolysis products (i.e. maltooligosaccharides; MOS). However, the structural specificity of oligosaccharides that elicit such perception is not known. This study investigated taste perception of pullulan-derived oligosaccharides (PDOS) that are structurally similar to MOS, but differ in that every third glycosidic linkage in PDOS is α-1,6, rather than α-1,4. Three food-grade PDOS stimuli were produced by limited-enzyme hydrolysis of pullulan. The resulting products were stimuli with degree of polymerization (DP) of 3, 6, and 9. Subjects discriminated all 3 stimuli from blanks at a significant level (P < 0.00001) in the absence of lactisole, a sweet taste inhibitor. In the presence of lactisole, the subjects could not detect DP 3 at a significant level (P > 0.05), but were able to detect DP 6 and 9 (P < 0.005), although the degree of detectability dropped significantly (P < 0.05). In a follow-up qualitative study, subjects made the target stimuli and glucose into 2 groups (glucose/DP 3 vs. DP 6/DP 9) and characterized both groups as mostly "sweet" with having different sweetness intensity. With lactisole, they described glucose and DP 3 as "taste like blank" (lactisole water) and found it challenging to describe DP 6 and 9 stimuli due to their subtle nature. These results suggest that taste perception of PDOS primarily depends on the sweet taste receptor, although they may elicit other sensory attributes; this is strikingly different from the reported taste of MOS. The potential impact of structural configuration on taste perception is further discussed.
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Affiliation(s)
- Shashwat Damani
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, United States
| | - Michael H Penner
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, United States
| | - Juyun Lim
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, United States
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Deng W, Zhou D, Li J, Zheng J, Zhou Z. A Potent Mechanism for Revealing Structurally Manipulated Sweetness Inhibitory Property of Lactisole Derivatives. Food Chem 2022. [DOI: 10.1016/j.foodchem.2022.134769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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9
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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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Khramova DS, Popov SV. A secret of salivary secretions: Multimodal effect of saliva in sensory perception of food. Eur J Oral Sci 2021; 130:e12846. [PMID: 34935208 DOI: 10.1111/eos.12846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 11/12/2021] [Indexed: 01/15/2023]
Abstract
Saliva plays multifunctional roles in oral cavity. Even though its importance for the maintenance of oral health has long been established, the role of saliva in food perception has attracted increasing attention in recent years. We encourage researchers to discover the peculiarity of this biological fluid and aim to combine the data concerning all aspects of the saliva influence on the sensory perception of food. This review presents saliva as a unique material, which modulates food perception due to constant presence of saliva in the mouth and thanks to its composition. Therefore, we highlight the salivary components that contribute to these effects. Moreover, this review is an attempt to structure the effects of saliva on perception of different food categories, where the mechanisms of salivary impact in perception of liquid, semi-solid, and solid foods are revealed. Finally, we emphasize that the large inter-individual variability in salivary composition and secretion appear to contribute to the fact that everyone experiences food in their own way. Therefore, the design of the sensory studies should consider the properties of volunteers' saliva and also carefully monitor the experimental conditions that affect salivary composition and flow rate.
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Affiliation(s)
- Daria S Khramova
- Department of Molecular Immunology and Biotechnology, Institute of Physiology of Коmi Science Centre of the Ural Branch of the Russian Academy of Sciences, FRC Komi SC UB RAS, Syktyvkar, Russia
| | - Sergey V Popov
- Department of Molecular Immunology and Biotechnology, Institute of Physiology of Коmi Science Centre of the Ural Branch of the Russian Academy of Sciences, FRC Komi SC UB RAS, Syktyvkar, Russia
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Chromatographic preparation of food-grade prebiotic oligosaccharides with defined degree of polymerization. Food Chem 2021; 373:131542. [PMID: 34782210 PMCID: PMC8678371 DOI: 10.1016/j.foodchem.2021.131542] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 11/23/2022]
Abstract
Prebiotic oligosaccharides are of widespread interest in the food industry due to their potential health benefits. This has triggered a need for research into their sensory properties. Such research is currently limited due to the lack of available food-grade oligosaccharide preparations with specific degree of polymerization (DP). The aim of this study was to develop economical approaches for the preparation and characterization of prebiotic oligosaccharides differing with respect to composition and DP. Such preparations were prepared by chromatographic fractionation of commercially available prebiotic mixtures using microcrystalline cellulose stationary phases and aqueous ethanol mobile phases. This approach is shown to work for the preparation of food-grade fructooligosaccharides of DP 3 and 4, galactooligosaccharides of DP 3 and 4, and xylooligosaccharides of DP 2-4. Methods for the characterization of the different classes of oligosaccharides are also presented including those addressing purity, identity, total carbohydrate content, moles per unit mass, and DP.
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12
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Pullicin AJ, Glendinning JI, Lim J. Cephalic phase insulin release: A review of its mechanistic basis and variability in humans. Physiol Behav 2021; 239:113514. [PMID: 34252401 PMCID: PMC8440382 DOI: 10.1016/j.physbeh.2021.113514] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 06/16/2021] [Accepted: 06/30/2021] [Indexed: 12/17/2022]
Abstract
Cephalic phase insulin release (CPIR) is a transient pulse of insulin that occurs within minutes of stimulation from foods or food-related stimuli. Despite decades of research on CPIR in humans, the body of literature surrounding this phenomenon is controversial due in part to contradictory findings . This has slowed progress towards understanding the sensory and neural basis of CPIR, as well as its overall relevance to health. This review examines up-to-date knowledge in CPIR research and identifies sources of CPIR variability in humans in an effort to guide future research. The review starts by defining CPIR and discussing its presumed functional roles in glucose homeostasis and feeding behavior. Next, the types of stimuli that have been reported to elicit CPIR, as well as the sensory and neural mechanisms underlying the response in rodents and humans are discussed, and areas where knowledge is limited are identified. Finally, factors that may contribute to the observed variability of CPIR in humans are examined, including experimental design, test procedure, and individual characteristics. Overall, oral stimulation appears to be important for eliciting CPIR, especially when combined with other sensory modalities (vision, olfaction, somatosensation). While differences in experimental design and testing procedure likely explain some of the observed inter- and intra-study variability, individual differences also appear to play an important role. Understanding sources of these individual differences in CPIR will be key for establishing its health relevance.
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Affiliation(s)
- Alexa J Pullicin
- Department of Food Science & Technology, Oregon State University, Corvallis, OR 97331, USA
| | - John I Glendinning
- Departments of Biology and Neuroscience & Behavior, Barnard College, Columbia University, 3009 Broadway, New York, NY 10027 US
| | - Juyun Lim
- Department of Food Science & Technology, Oregon State University, Corvallis, OR 97331, USA.
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13
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Gutierrez R, Simon SA. Physiology of Taste Processing in the Tongue, Gut, and Brain. Compr Physiol 2021; 11:2489-2523. [PMID: 34558667 DOI: 10.1002/cphy.c210002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The gustatory system detects and informs us about the nature of various chemicals we put in our mouth. Some of these have nutritive value (sugars, amino acids, salts, and fats) and are appetitive and avidly ingested, whereas others (atropine, quinine, nicotine) are aversive and rapidly rejected. However, the gustatory system is mainly responsible for evoking the perception of a limited number of qualities that humans taste as sweet, umami, bitter, sour, salty, and perhaps fat [free fatty acids (FFA)] and starch (malto-oligosaccharides). The complex flavors and mouthfeel that we experience while eating food result from the integration of taste, odor, texture, pungency, and temperature. The latter three arise primarily from the somatosensory (trigeminal) system. The sensory organs used for detecting and transducing many chemicals are found in taste buds (TBs) located throughout the tongue, soft palate esophagus, and epiglottis. In parallel with the taste system, the trigeminal nerve innervates the peri-gemmal epithelium to transmit temperature, mechanical stimuli, and painful or cooling sensations such as those produced by changes in temperature as well as from chemicals like capsaicin and menthol, respectively. This article gives an overview of the current knowledge about these TB cells' anatomy and physiology and their trigeminal induced sensations. We then discuss how taste is represented across gustatory cortices using an intermingled and spatially distributed population code. Finally, we review postingestion processing (interoception) and central integration of the tongue-gut-brain interaction, ultimately determining our sensations as well as preferences toward the wholesomeness of nutritious foods. © 2021 American Physiological Society. Compr Physiol 11:1-35, 2021.
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Affiliation(s)
- Ranier Gutierrez
- Laboratory of Neurobiology of Appetite, Department of Pharmacology, CINVESTAV, Mexico City, Mexico
| | - Sidney A Simon
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA
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14
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Clouard C, Lannuzel C, Bourgot CL, Gerrits WJJ. Lactose and Digestible Maltodextrin in Milk Replacers Differently Affect Energy Metabolism and Substrate Oxidation: A Calorimetric Study in Piglets. J Nutr 2020; 150:3114-3122. [PMID: 33097931 DOI: 10.1093/jn/nxaa296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/13/2020] [Accepted: 09/09/2020] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND In recent years, lactose-free infant formulas have been increasingly used. Digestible maltodextrins are commonly used as a substitute for lactose in these formulas, but the effects on energy metabolism are unknown. OBJECTIVE We aimed to evaluate the differences in energy metabolism and substrate oxidation in piglets fed milk replacers containing lactose compared with maltodextrin as the only source of carbohydrates. METHODS Piglets (Tempo × Topigs 20) from 8 litters were fed milk replacers containing lactose or maltodextrin (28% w/w, milk powder basis) from 1 to 9 wk of age (n = 4 litters/milk replacer). At 5 wk of age, 4 females and 4 entire males (mean ± SEM bodyweight, 10 ± 0.3 kg) were selected per litter, and housed in 16 groups of 4 littermates, with 2 females and 2 males per pen (n = 8 groups/milk replacer). Between 7 and 9 wk of age, groups were housed for 72 h in climate respiration chambers, and fed their experimental milk replacer in 2 meals per day, at 08:30 and 16:30. Heat production data were calculated from the continuous measurement of gaseous exchanges and analyzed using general linear models in SAS. RESULTS Resting metabolic rate was 6% less in maltodextrin- than in lactose-fed piglets, notably before the morning meal. The postprandial respiratory quotient was 13% greater in maltodextrin- than in lactose-fed piglets after both meals. Net rates of carbohydrate oxidation were on average 5% greater in maltodextrin- than in lactose-fed piglets, particularly after the afternoon meal, whereas net rates of fat oxidation were 9% less in maltodextrin- than in lactose-fed piglets, particularly after the morning meal. CONCLUSIONS Compared with lactose, maltodextrin in milk replacers reduced resting metabolic rate in the fasting state, and induced a shift in postprandial substrate oxidation profiles in pigs. Further research is warranted to evaluate the consequences of these metabolic changes for body composition.
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Affiliation(s)
- Caroline Clouard
- Adaptation Physiology Group, Department of Animal Sciences, Wageningen University & Research, Wageningen, The Netherlands
| | - Corentin Lannuzel
- Animal Nutrition Group, Department of Animal Sciences, Wageningen University & Research, Wageningen, The Netherlands
| | | | - Walter J J Gerrits
- Animal Nutrition Group, Department of Animal Sciences, Wageningen University & Research, Wageningen, The Netherlands
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15
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Ahmad R, Dalziel JE. G Protein-Coupled Receptors in Taste Physiology and Pharmacology. Front Pharmacol 2020; 11:587664. [PMID: 33390961 PMCID: PMC7774309 DOI: 10.3389/fphar.2020.587664] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/09/2020] [Indexed: 12/14/2022] Open
Abstract
Heterotrimeric G protein-coupled receptors (GPCRs) comprise the largest receptor family in mammals and are responsible for the regulation of most physiological functions. Besides mediating the sensory modalities of olfaction and vision, GPCRs also transduce signals for three basic taste qualities of sweet, umami (savory taste), and bitter, as well as the flavor sensation kokumi. Taste GPCRs reside in specialised taste receptor cells (TRCs) within taste buds. Type I taste GPCRs (TAS1R) form heterodimeric complexes that function as sweet (TAS1R2/TAS1R3) or umami (TAS1R1/TAS1R3) taste receptors, whereas Type II are monomeric bitter taste receptors or kokumi/calcium-sensing receptors. Sweet, umami and kokumi receptors share structural similarities in containing multiple agonist binding sites with pronounced selectivity while most bitter receptors contain a single binding site that is broadly tuned to a diverse array of bitter ligands in a non-selective manner. Tastant binding to the receptor activates downstream secondary messenger pathways leading to depolarization and increased intracellular calcium in TRCs, that in turn innervate the gustatory cortex in the brain. Despite recent advances in our understanding of the relationship between agonist binding and the conformational changes required for receptor activation, several major challenges and questions remain in taste GPCR biology that are discussed in the present review. In recent years, intensive integrative approaches combining heterologous expression, mutagenesis and homology modeling have together provided insight regarding agonist binding site locations and molecular mechanisms of orthosteric and allosteric modulation. In addition, studies based on transgenic mice, utilizing either global or conditional knock out strategies have provided insights to taste receptor signal transduction mechanisms and their roles in physiology. However, the need for more functional studies in a physiological context is apparent and would be enhanced by a crystallized structure of taste receptors for a more complete picture of their pharmacological mechanisms.
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Affiliation(s)
- Raise Ahmad
- Food Nutrition and Health Team, Food and Bio-based Products Group, AgResearch, Palmerston North, New Zealand
| | - Julie E Dalziel
- Food Nutrition and Health Team, Food and Bio-based Products Group, AgResearch, Palmerston North, New Zealand
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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: 4] [Impact Index Per Article: 1.0] [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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17
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Aji GK, Warren FJ, Roura E. Salivary α-Amylase Activity and Starch-Related Sweet Taste Perception in Humans. Chem Senses 2020; 44:249-256. [PMID: 30753419 DOI: 10.1093/chemse/bjz010] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Starch-related sweet taste perception plays an important role as a part of the dietary nutrient sensing mechanisms in the oral cavity. However, the release of sugars from starchy foods eliciting sweetness has been less studied in humans than in laboratory rodents. Thus, 28 respondents were recruited and evaluated for their starch-related sweet taste perception, salivary alpha-amylase (sAA) activity, oral release of reducing sugars, and salivary leptin. The results demonstrated that a 2-min oral mastication of starchy chewing gum produced an oral concentration of maltose above the sweet taste threshold and revealed that the total amount of maltose equivalent reducing sugars produced was positively correlated with the sAA activity. In addition, respondents who consistently identified the starch-related sweet taste in two sessions (test and retest) generated a higher maltose equivalent reducing sugar concentration compared to respondents who could not detect starch-related sweet taste at all (51.52 ± 2.85 and 29.96 ± 15.58 mM, respectively). In our study, salivary leptin levels were not correlated with starch-related sweet taste perception. The data contribute to the overall understanding of oral nutrient sensing and potentially to the control of food intake in humans. The results provide insight on how starchy foods without added glucose can elicit variable sweet taste perception in humans after mastication as a result of the maltose generated. The data contribute to the overall understanding of oral sensing of simple and complex carbohydrates in humans.
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Affiliation(s)
- Galih Kusuma Aji
- Centre for Nutrition and Food Sciences (CNAFS), Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, St. Lucia, Australia.,Centre of Technology for Agro-Industry, The Agency for Assessment and Application of Technology, Kompleks Perkantoran Puspiptek, Tangerang Selatan, Indonesia
| | | | - Eugeni Roura
- Centre for Nutrition and Food Sciences (CNAFS), Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, St. Lucia, Australia
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Pullicin AJ, Penner MH, Lim J. The Sweet Taste of Acarbose and Maltotriose: Relative Detection and Underlying Mechanism. Chem Senses 2020; 44:123-128. [PMID: 30590468 DOI: 10.1093/chemse/bjy081] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Although sweet-tasting saccharides possess similar molecular structures, their relative sweetness often varies to a considerable degree. Current understanding of saccharide structure/sweetness interrelationships is limited. Understanding how certain structural features of saccharides and/or saccharide analogs correlate to their relative sweetness can provide insight on the mechanisms underlying sweetness potency. Maltotriose is a short-chain glucose-based oligosaccharide, which we recently reported to elicit sweet taste. Acarbose, an α-glucosidase inhibitor, is a pseudo-saccharide that has an overall resemblance to a glucose-based oligosaccharide and thus may be viewed as a structural analog. During other studies, we recognized that acarbose can also elicit sweet taste. Here, we formally investigated the underlying taste detection mechanism of acarbose, while confirming our previous findings for maltotriose. We found that subjects could detect the sweet taste of acarbose and maltotriose in aqueous solutions but were not able to detect them in the presence of a sweet taste inhibitor lactisole. These findings support that both are ligands of the human sweet taste receptor, hT1R2/hT1R3. In a separate experiment, we measured the relative sweetness detection of acarbose, maltotriose, and other sweet-tasting mono- and disaccharides (glucose, fructose, maltose, and sucrose). Whereas maltotriose was found to have a similar discriminability profile to glucose and maltose, the discriminability of acarbose matched that of fructose at the concentrations tested (18, 32, and 56 mM). These findings are discussed in terms of how specific molecular features (e.g., degree of polymerization and monomer composition) may contribute to the relative sweetness of saccharides.
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Affiliation(s)
- Alexa J Pullicin
- Department of Food Science and Technology, Oregon State University, Corvallis, OR, USA
| | - 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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Kashani-Amin E, Sakhteman A, Larijani B, Ebrahim-Habibi A. Presence of carbohydrate binding modules in extracellular region of class C G-protein coupled receptors (C GPCR): An in silico investigation on sweet taste receptor. J Biosci 2019; 44:138. [PMID: 31894119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Sweet taste receptor (STR) is a C GPCR family member and a suggested drug target for metabolic disorders such as diabetes. Detailed characteristics of the molecule as well as its ligand interactions mode are yet considerably unclear due to experimental study limitations of transmembrane proteins. An in silico study was designed to find the putative carbohydrate binding sites on STR. To this end, α-D-glucose and its α-1,4-oligomers (degree of polymerization up to 14) were chosen as probes and docked into an ensemble of different conformations of the extracellular region of STR monomers (T1R2 and T1R3), using AutoDock Vina. Ensembles had been sampled from an MD simulation experiment. Best poses were further energy-minimized in the presence of water molecules with Amber14 forcefield. For each monomer, four distinct binding regions consisting of one or two binding pockets could be distinguished. These regions were further investigated with regard to hydrophobicity and hydrophilicity of the residues, as well as residue compositions and non-covalent interactions with ligands. Popular binding regions showed similar characteristics to carbohydrate binding modules (CBM). Observation of several conserved or semi-conserved residues in these binding regions suggests a possibility to extrapolate the results to other C GPCR family members. In conclusion, presence of CBM in STR and, by extrapolation, in other C GPCR family members is suggested, similar to previously proposed sites in gut fungal C GPCRs, through transcriptome analyses. STR modes of interaction with carbohydrates are also discussed and characteristics of non-covalent interactions in C GPCR family are highlighted.
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Affiliation(s)
- Elaheh Kashani-Amin
- Biosensor Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
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20
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Presence of carbohydrate binding modules in extracellular region of class C G-protein coupled receptors (C GPCR): An in silico investigation on sweet taste receptor. J Biosci 2019. [DOI: 10.1007/s12038-019-9944-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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21
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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: 5.6] [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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22
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Savolainen S, Hautala J, Junnila J, Airaksinen S, Juppo AM, Raekallio M, Vainio O. Acceptability of flavoured pharmaceutically non-active mini-tablets in pet cats tested with a rapid 3-portal acceptance test with and without food. Vet Anim Sci 2019; 7:100054. [PMID: 32734075 PMCID: PMC7386771 DOI: 10.1016/j.vas.2019.100054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 02/22/2019] [Accepted: 02/28/2019] [Indexed: 01/19/2023] Open
Abstract
The palatability of synthetically flavoured mini-tablets in cats was investigated. 3-portal acceptance tests were carried out on 10–19 pet cats in their homes. The mini-tablets were not accepted voluntarily without food by most of the cats. Amino acids were not palatable to cats, which did not support the earlier studies. Most of the cats ate the mini-tablets concealed inside a palatable food item.
Palatable oral pharmaceuticals are crucial for feline medication. The pharmaceutical industry prefers synthetic flavours over organic ones because of hygiene and regulatory issues. The aim of this study was to find a palatable synthetic flavour for future taste-masking of feline pharmaceuticals. The hypothesis was that synthetic meat aromas and free amino acids would be palatable to cats. The palatability of 18 synthetically flavoured mini-tablets was screened with 10–19 pet cats using a rapid 3-portal acceptance test with and without food. The tested flavours were synthetic amino acids (L-carnitine, l-glutamic acid monosodium salt hydrate, l-leucine, l-methionine, l-phenylalanine, l-proline, and taurine), d-(+)-Maltose monohydrate and thiamine hydrochloride. Furthermore, thiamine hydrochloride was combined with amino acids (l-cysteine, l-leucine, l-methionine and l-proline) and synthetic meat flavours (2-acetylpyridine, 2-acetylthiazole, 2-pentylpyridine and 4-hydroxy-5-methyl-3(2H)-furanone). The negative control was a non-flavoured placebo mini-tablet, while positive controls were an organic yeast-flavoured mini-tablet and a yeast- and fish-based commercial vitamin tablet in mini-tablet form. No significant differences were detected between palatable synthetic flavours and the placebo, nor between the synthetic flavours and the yeast flavour. In general, the mini-tablet seemed to be small enough to be accepted inside a food item. These results differ from the earlier literature about the taste preferences of cats for amino acids, and hence free amino acids should not be considered palatable to cats based purely on previous findings.
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Affiliation(s)
- S Savolainen
- Department of Equine and Small Animal Medicine, University of Helsinki, P.O. Box 57, 00014 University of Helsinki, Finland
| | - J Hautala
- Division of Pharmaceutical Chemistry and Technology, University of Helsinki, P.O. Box 56, 00014 University of Helsinki, Finland
| | - J Junnila
- 4Pharma Ltd, Arkadiankatu 7, 00100 Helsinki, Finland
| | - S Airaksinen
- Division of Pharmaceutical Chemistry and Technology, University of Helsinki, P.O. Box 56, 00014 University of Helsinki, Finland
| | - A M Juppo
- Division of Pharmaceutical Chemistry and Technology, University of Helsinki, P.O. Box 56, 00014 University of Helsinki, Finland
| | - M Raekallio
- Department of Equine and Small Animal Medicine, University of Helsinki, P.O. Box 57, 00014 University of Helsinki, Finland
| | - O Vainio
- Department of Equine and Small Animal Medicine, University of Helsinki, P.O. Box 57, 00014 University of Helsinki, Finland
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Martin C, Issanchou S. Nutrient sensing: What can we learn from different tastes about the nutrient contents in today’s foods? Food Qual Prefer 2019. [DOI: 10.1016/j.foodqual.2018.07.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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24
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Sweetness and sensory properties of commercial and novel oligosaccharides of prebiotic potential. Lebensm Wiss Technol 2018. [DOI: 10.1016/j.lwt.2018.07.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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25
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Colvin JL, Pullicin AJ, Lim J. Regional Differences in Taste Responsiveness: Effect of Stimulus and Tasting Mode. Chem Senses 2018; 43:645-653. [DOI: 10.1093/chemse/bjy055] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Affiliation(s)
- Julie L Colvin
- Department of Food Science and Technology, Oregon State University, Wiegand Hall, Corvallis, OR, USA
| | - Alexa J Pullicin
- Department of Food Science and Technology, Oregon State University, Wiegand Hall, Corvallis, OR, USA
| | - Juyun Lim
- Department of Food Science and Technology, Oregon State University, Wiegand Hall, Corvallis, OR, USA
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26
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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: 14] [Impact Index Per Article: 2.3] [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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Preparation and characterization of isolated low degree of polymerization food-grade maltooligosaccharides. Food Chem 2018; 246:115-120. [PMID: 29291829 DOI: 10.1016/j.foodchem.2017.10.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 09/01/2017] [Accepted: 10/09/2017] [Indexed: 11/21/2022]
Abstract
Research involving human responses to the consumption of starch and its hydrolysis products would benefit from convenient sources of well defined, low cost, food-grade maltooligosaccharides (MOS). This report addresses such need by presenting an approach to obtain aforementioned MOS. A chromatography-ready MOS sample containing proportionately high amounts of low degree of polymerization (DP) MOS is initially prepared from commercially-available maltodextrins (MD) by taking advantage of the DP-dependent differential solubility of MOS in aqueous-ethanol solutions. The low DP-enriched MOS preparation is subsequently fractionated via preparative column chromatography using cellulose-based stationary phases and step-gradient aqueous-ethanol mobile phases. The resulting fractions yielded isolated food-grade MOS ranging in DP from 3 to 7. NMR spectra of isolated MOS indicated minimal amounts of branched saccharides. Typical yields from a single fractionation protocol (2 g MD starting material), including solvent partitioning through preparative chromatography, ranged from ∼40 mg for DP 4, 5, and 7 to ∼100 mg for DP 3 and 6.
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28
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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: 3.7] [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
- *Correspondence: Richard L. Young
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