1
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Choi Y, Wong RR, Cha YK, Park TH, Kim Y, Chung SJ. Sweet-bitter taste interactions in binary mixtures of sweeteners: Relationship between taste receptor activities and sensory perception. Food Chem 2024; 459:140343. [PMID: 39018621 DOI: 10.1016/j.foodchem.2024.140343] [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: 03/22/2024] [Revised: 06/28/2024] [Accepted: 07/03/2024] [Indexed: 07/19/2024]
Abstract
This study investigated the effects of various binary sweetener mixtures on sweetness enhancement and their interactions with sweet or bitter taste receptors, focusing on sensory perception and receptor activity. Acesulfame K or saccharin was mixed with allulose, aspartame, erythritol, fructose, glucose, or sucrose to match a target sucrose sweetness. The effects of the mixtures on sweet and bitter taste receptors (in the human embryonic kidney -293 cells) and sensory taste intensities were evaluated. Sweetness enhancement at the sweet taste receptor level was observed in some cases, with several monosaccharides reducing the acesulfame K- or saccharin-induced bitter taste receptor activity. Combining acesulfame K or saccharin with any of the six sweeteners perceptually enhanced sweetness (60% ∼ 100% in 50:50 ratio), correlating with a reduction in inherent bitterness (-35% ∼ -63% in 50:50 ratio). This finding suggests that sweetness perception likely increased because the monosaccharides mitigate the activation of bitter receptors caused by high-potency sweeteners.
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Affiliation(s)
- Yoonha Choi
- Department of Nutritional Science and Food Management, Ewha Womans University, Seoul 03760, Republic of Korea.
| | - Run Rou Wong
- Department of Nutritional Science and Food Management, Ewha Womans University, Seoul 03760, Republic of Korea.
| | - Yeon Kyung Cha
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul 08826, Republic of Korea.
| | - Tai Hyun Park
- Department of Nutritional Science and Food Management, Ewha Womans University, Seoul 03760, Republic of Korea; Interdisciplinary Program in Bioengineering, Seoul National University, Seoul 08826, Republic of Korea.
| | - Yuri Kim
- Department of Nutritional Science and Food Management, Ewha Womans University, Seoul 03760, Republic of Korea; Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea.
| | - Seo-Jin Chung
- Department of Nutritional Science and Food Management, Ewha Womans University, Seoul 03760, Republic of Korea.
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2
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Moribayashi T, Nakao Y, Ohtubo Y. Characteristics of A-type voltage-gated K + currents expressed on sour-sensing type III taste receptor cells in mice. Cell Tissue Res 2024; 396:353-369. [PMID: 38492001 PMCID: PMC11144136 DOI: 10.1007/s00441-024-03887-6] [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: 10/26/2023] [Accepted: 03/06/2024] [Indexed: 03/18/2024]
Abstract
Sour taste is detected by type III taste receptor cells that generate membrane depolarization with action potentials in response to HCl applied to the apical membranes. The shape of action potentials in type III cells exhibits larger afterhyperpolarization due to activation of transient A-type voltage-gated K+ currents. Although action potentials play an important role in neurotransmitter release, the electrophysiological features of A-type K+ currents in taste buds remain unclear. Here, we examined the electrophysiological properties of A-type K+ currents in mouse fungiform taste bud cells using in-situ whole-cell patch clamping. Type III cells were identified with SNAP-25 immunoreactivity and/or electrophysiological features of voltage-gated currents. Type III cells expressed A-type K+ currents which were completely inhibited by 10 mM TEA, whereas IP3R3-immunoreactive type II cells did not. The half-maximal activation and steady-state inactivation of A-type K+ currents were 17.9 ± 4.5 (n = 17) and - 11.0 ± 5.7 (n = 17) mV, respectively, which are similar to the features of Kv3.3 and Kv3.4 channels (transient and high voltage-activated K+ channels). The recovery from inactivation was well fitted with a double exponential equation; the fast and slow time constants were 6.4 ± 0.6 ms and 0.76 ± 0.26 s (n = 6), respectively. RT-PCR experiments suggest that Kv3.3 and Kv3.4 mRNAs were detected at the taste bud level, but not at single-cell levels. As the phosphorylation of Kv3.3 and Kv3.4 channels generally leads to the modulation of cell excitability, neuromodulator-mediated A-type K+ channel phosphorylation likely affects the signal transduction of taste.
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Affiliation(s)
- Takeru Moribayashi
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan
| | - Yoshiki Nakao
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan
| | - Yoshitaka Ohtubo
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan.
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Baranek E, Heraud C, Larroquet L, Surget A, Lanuque A, Terrier F, Skiba-Cassy S, Jérôme R. Long-term regulation of fat sensing in rainbow trout ( Oncorhynchus mykiss) fed a vegetable diet from the first feeding: focus on free fatty acid receptors and their signalling. Br J Nutr 2024; 131:1-16. [PMID: 37469170 DOI: 10.1017/s0007114523001599] [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] [Indexed: 07/21/2023]
Abstract
Taste plays a fundamental role in an animal’s ability to detect nutrients and transmits key dietary information to the brain, which is crucial for its growth and survival. Providing alternative terrestrial ingredients early in feeding influences the growth of rainbow trout (RT, Oncorhynchus mykiss). Thus, the present study aimed to assess the influence, via long-term feeding (from the first feeding to 8 months), of alternative plant ingredients (V diet for vegetable diet v. C diet for a control diet) in RT on the mechanism of fat sensing at the gustatory level. After the feeding trial, we studied the pathways of the fat-sensing mechanism in tongue tissue and the integrated response in the brain. To this end, we analysed the expression pattern of free fatty acid receptors (ffar) 1 and 2, markers of calcium-signalling pathways (phospholipase Cβ, Orai, Stim or Serca), the serotonin level (a key neurotransmitter in taste buds) and the expression pattern of appetite-regulating neuropeptides in the hypothalamus (central area of appetite regulation). The results revealed that the V diet modified the expression pattern of ffar1 and paralogs of ffar2 genes in tongue tissue, along with differential regulation of calcium-signalling pathways and a defect in serotonin level and brain turnover, without influencing neuropeptide expression. This study is the first to support that changes in feeding behaviour of RT fed a V diet could be due to the difference in nutrient sensing and a decrease in hedonic sensation. We revealed that RT have similar fat-detection mechanisms as mammals.
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Affiliation(s)
- Elodie Baranek
- INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, UMR1419 Nutrition Metabolism and Aquaculture, Aquapôle, F-64310 Saint-Pée-sur-Nivelle, France
| | - Cécile Heraud
- INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, UMR1419 Nutrition Metabolism and Aquaculture, Aquapôle, F-64310 Saint-Pée-sur-Nivelle, France
| | - Laurence Larroquet
- INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, UMR1419 Nutrition Metabolism and Aquaculture, Aquapôle, F-64310 Saint-Pée-sur-Nivelle, France
| | - Anne Surget
- INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, UMR1419 Nutrition Metabolism and Aquaculture, Aquapôle, F-64310 Saint-Pée-sur-Nivelle, France
| | - Anthony Lanuque
- INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, UMR1419 Nutrition Metabolism and Aquaculture, Aquapôle, F-64310 Saint-Pée-sur-Nivelle, France
| | - Frederic Terrier
- INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, UMR1419 Nutrition Metabolism and Aquaculture, Aquapôle, F-64310 Saint-Pée-sur-Nivelle, France
| | - Sandrine Skiba-Cassy
- INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, UMR1419 Nutrition Metabolism and Aquaculture, Aquapôle, F-64310 Saint-Pée-sur-Nivelle, France
| | - Roy Jérôme
- INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, UMR1419 Nutrition Metabolism and Aquaculture, Aquapôle, F-64310 Saint-Pée-sur-Nivelle, France
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4
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Jensterle M, DeVries JH, Battelino T, Battelino S, Yildiz B, Janez A. Glucagon-like peptide-1, a matter of taste? Rev Endocr Metab Disord 2021; 22:763-775. [PMID: 33123893 DOI: 10.1007/s11154-020-09609-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/26/2020] [Indexed: 01/22/2023]
Abstract
Understanding of gustatory coding helps to predict, and perhaps even modulate the ingestive decision circuitry, especially when eating behaviour becomes dysfunctional. Preclinical research demonstrated that glucagon like peptide 1 (GLP-1) is locally synthesized in taste bud cells in the tongue and that GLP-1 receptor exists on the gustatory nerves in close proximity to GLP-1 containing taste bud cells. In humans, the tongue has not yet been addressed as clinically relevant target for GLP-1 based therapies. The primary aim of the current review was to elaborate on the role of GLP- 1 in mammalian gustatory system, in particular in the perception of sweet. Secondly, we aimed to explore what modulates gustatory coding and whether the GLP-1 based therapies might be involved in regulation of taste perception. We performed a series of PubMed, Medline and Embase databases systemic searches. The Population-Intervention-Comparison-Outcome (PICO) framework was used to identify interventional studies. Based on the available data, GLP-1 is specifically involved in the perception of sweet. Aging, diabetes and obesity are characterized by diminished taste and sweet perception. Calorie restriction and bariatric surgery are associated with a diminished appreciation of sweet food. GLP-1 receptor agonists (RAs) modulate food preference, yet its modulatory potential in gustatory coding is currently unknown. Future studies should explore whether GLP-1 RAs modulate taste perception to the extent that changes of food preference and consumption ensue.
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Affiliation(s)
- Mojca Jensterle
- Division of Internal Medicine, Department of Endocrinology, Diabetes and Metabolic Diseases, University Medical Centre Ljubljana, Zaloška cesta, 7, 1000, Ljubljana, Slovenia
- Department of Internal Medicine, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia, Zaloška cesta 7, 1000, Ljubljana, Slovenia
| | - J Hans DeVries
- Department of Endocrinology and Metabolism, Amsterdam University Medical Center, University of Amsterdam, Meibergdreef 9, 1105, AZ, Amsterdam, The Netherlands
| | - Tadej Battelino
- Department of Endocrinology, Diabetes and Metabolism, University Children's Hospital, University Medical Centre Ljubljana, Bohoričeva 20, SI-1000, Ljubljana, Slovenia
- Department of Pediatrics, Faculty of Medicine, University of Ljubljana, Bohoričeva 20, SI-1000, Ljubljana, Slovenia
| | - Saba Battelino
- Department of Otorhinolaryngology and Cervicofacial Surgery, University Medical Centre Ljubljana, Zaloska cesta 2, 1000, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Bulent Yildiz
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Hacettepe University School of Medicine, Hacettepe, 06100, Ankara, Turkey
| | - Andrej Janez
- Division of Internal Medicine, Department of Endocrinology, Diabetes and Metabolic Diseases, University Medical Centre Ljubljana, Zaloška cesta, 7, 1000, Ljubljana, Slovenia.
- Department of Internal Medicine, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia, Zaloška cesta 7, 1000, Ljubljana, Slovenia.
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5
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Bhat EA, Sajjad N, Banawas S, Khan J. Human CALHM5: Insight in large pore lipid gating ATP channel and associated neurological pathologies. Mol Cell Biochem 2021; 476:3711-3718. [PMID: 34089472 DOI: 10.1007/s11010-021-04198-y] [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: 01/15/2021] [Accepted: 05/27/2021] [Indexed: 10/21/2022]
Abstract
Recently calcium homeostasis modulators (CALHMs) are identified as ATP release channels play crucial role in functioning of neurons including gustatory signaling and neuronal excitability. Pathologies of Alzheimer's disease and depression have been associated with the dysfunction of CALHMs. Recently, CALHMs has been emerged as an important therapeutic research particularly in neurobiological studies. CALHM1 is most extensively studied among CALHMs and is an ATP and ion channel that is activated by membrane depolarization or removal of extracellular Ca2+. Despite the emerged role of CALHM5 shown by an recently assembled data; however, the neuronal function remains obscure until the first Cryo-EM structure of CALHM5 was recently solved by various research group which acts as a template to study the hidden functional properties of the CALHM5 protein based on structure function mechanism. It provides insight in some of the different pathophysiological roles. CALHM5 structure showed an abnormally large pore channel structure assembled as an undecamer with four transmembrane helices (TM1-TM4), an N-terminal helix (NTH), an extracellular loop region and an intracellular C-terminal domain (CTD) that consists of three α-helices CH1-3. The TM1 and NTH were always poorly defined among all CALHMs; however, these regions were well defined in CALHM5 channel structure. In this context, this review will provide insight in structure, function and mechanism to understand its significant role in pathological diseases particularly in Alzheimer's disease. Moreover, it focuses on CALHM5 structure and recent associated properties based on Cryo-EM research.
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Affiliation(s)
- Eijaz Ahmed Bhat
- Life Science Institute, Zhejiang University, Hangzhou, Zhejiang, 310058, P.R. China. .,Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, India.
| | - Nasreena Sajjad
- Department of Biochemistry, University of Kashmir, Hazratbal, Jammu and Kashmir, India
| | - Saeed Banawas
- Department of Medical Laboratory Sciences, College of Applied Medical Sciences, Majmaah University, Majmaah, 11952, Kingdom of Saudi Arabia. .,Health and Basic Sciences Research Center, Majmaah University, Majmaah, 11952, Saudi Arabia. .,Departments of Biomedical Sciences, Oregon State University, Corvallis, OR, 97331, USA.
| | - Johra Khan
- Department of Medical Laboratory Sciences, College of Applied Medical Sciences, Majmaah University, Majmaah, 11952, Kingdom of Saudi Arabia.,Health and Basic Sciences Research Center, Majmaah University, Majmaah, 11952, Saudi Arabia
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6
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Jensterle M, Rizzo M, Janez A. Glucagon-Like Peptide 1 and Taste Perception: From Molecular Mechanisms to Potential Clinical Implications. Int J Mol Sci 2021; 22:ijms22020902. [PMID: 33477478 PMCID: PMC7830704 DOI: 10.3390/ijms22020902] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/03/2021] [Accepted: 01/15/2021] [Indexed: 12/14/2022] Open
Abstract
Preclinical studies provided some important insights into the action of glucagon-like peptide 1 (GLP-1) in taste perception. This review examines the literature to uncover some molecular mechanisms and connections between GLP-1 and the gustatory coding. Local GLP-1 production in the taste bud cells, the expression of GLP-1 receptor on the adjacent nerves, a functional continuum in the perception of sweet chemicals from the gut to the tongue and an identification of GLP-1 induced signaling pathways in peripheral and central gustatory coding all strongly suggest that GLP-1 is involved in the taste perception, especially sweet. However, the impact of GLP-1 based therapies on gustatory coding in humans remains largely unaddressed. Based on the molecular background we encourage further exploration of the tongue as a new treatment target for GLP-1 receptor agonists in clinical studies. Given that pharmacological manipulation of gustatory coding may represent a new potential strategy against obesity and diabetes, the topic is of utmost clinical relevance.
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Affiliation(s)
- Mojca Jensterle
- Diabetes and Metabolic Diseases, Division of Internal Medicine, Department of Endocrinology, University Medical Centre Ljubljana, Zaloška Cesta 7, 1000 Ljubljana, Slovenia;
- Department of Internal Medicine, Faculty of Medicine, University of Ljubljana, Zaloška Cesta 7, 1000 Ljubljana, Slovenia
| | - Manfredi Rizzo
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of South Carolina, Columbia, SC 29208, USA;
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties, University of Palermo, 90133 Palermo, Italy
| | - Andrej Janez
- Diabetes and Metabolic Diseases, Division of Internal Medicine, Department of Endocrinology, University Medical Centre Ljubljana, Zaloška Cesta 7, 1000 Ljubljana, Slovenia;
- Department of Internal Medicine, Faculty of Medicine, University of Ljubljana, Zaloška Cesta 7, 1000 Ljubljana, Slovenia
- Correspondence: ; Tel.: +386-1-522-3114; Fax: +386-1-522-9359
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7
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Abstract
Understanding of gustatory coding helps to predict, and perhaps even modulate the ingestive decision circuitry, especially when eating behaviour becomes dysfunctional. Preclinical research demonstrated that glucagon like peptide 1 (GLP-1) is locally synthesized in taste bud cells in the tongue and that GLP-1 receptor exists on the gustatory nerves in close proximity to GLP-1 containing taste bud cells. In humans, the tongue has not yet been addressed as clinically relevant target for GLP-1 based therapies. The primary aim of the current review was to elaborate on the role of GLP- 1 in mammalian gustatory system, in particular in the perception of sweet. Secondly, we aimed to explore what modulates gustatory coding and whether the GLP-1 based therapies might be involved in regulation of taste perception. We performed a series of PubMed, Medline and Embase databases systemic searches. The Population-Intervention-Comparison-Outcome (PICO) framework was used to identify interventional studies. Based on the available data, GLP-1 is specifically involved in the perception of sweet. Aging, diabetes and obesity are characterized by diminished taste and sweet perception. Calorie restriction and bariatric surgery are associated with a diminished appreciation of sweet food. GLP-1 receptor agonists (RAs) modulate food preference, yet its modulatory potential in gustatory coding is currently unknown. Future studies should explore whether GLP-1 RAs modulate taste perception to the extent that changes of food preference and consumption ensue.
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8
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Fat taste signal transduction and its possible negative modulator components. Prog Lipid Res 2020; 79:101035. [DOI: 10.1016/j.plipres.2020.101035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/26/2020] [Accepted: 04/29/2020] [Indexed: 02/07/2023]
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9
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Yun J, Cho AN, Cho SW, Nam YS. DNA-mediated self-assembly of taste cells and neurons for taste signal transmission. Biomater Sci 2019; 6:3388-3396. [PMID: 30371689 DOI: 10.1039/c8bm00873f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cells can communicate with one another through physical connections and chemical signaling, activating various signaling pathways that can affect cellular functions and behaviors. In taste buds, taste cells transmit taste information to neurons via paracrine signaling. However, no previous studies have reported the in vitro co-culture of taste and neuronal cells, which allows us to monitor intercellular communications and better understand the mechanism of taste perception. Here, we introduce the first investigation on the proximate assembly and co-culture of taste cells and neurons to monitor the intercellular transmission of taste signals. Taste cells and neurons are placed closely using a pair of single-stranded oligonucleotides conjugated with polyethylene glycol and a phospholipid. Complementary oligonucleotide conjugates are anchored into the cellular membrane of neonatal taste cells and embryonic hippocampal neuronal cells, respectively, and then the cells are self-assembled into a functional multicellular unit for taste perception. Treatment of the assembled cells with a bitter tastant generates the sequential influx of calcium ions into the cytoplasm in taste cells and then in neuronal cells. Our work demonstrates that the cellular self-assembly is critical for efficient taste signal transduction, which can be used as a promising platform to construct cell-based biosensors for taste sensing.
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Affiliation(s)
- Junsu Yun
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea.
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10
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Witt M. Anatomy and development of the human taste system. HANDBOOK OF CLINICAL NEUROLOGY 2019; 164:147-171. [DOI: 10.1016/b978-0-444-63855-7.00010-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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11
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Pan HR, Tian M, Xue JB, Li SM, Luo XC, Huang X, Chen ZH, Huang L. Mammalian Taste Bud Cells Utilize Extragemmal 5-Hydroxy-L-Tryptophan to Biosynthesize the Neurotransmitter Serotonin. Front Cell Neurosci 2018; 12:461. [PMID: 30534058 PMCID: PMC6275321 DOI: 10.3389/fncel.2018.00461] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 11/12/2018] [Indexed: 01/31/2023] Open
Abstract
Serotonin or 5-hydroxytryptamine (5-HT) is an important neurotransmitter that is found in mammalian taste buds and can regulate the output of intragemmal signaling networks onto afferent nerve fibers. However, it is unclear how 5-HT is produced, synthesized locally inside taste buds or absorbed from outside sources. In this study, we attempt to address this question by delineating the process of possible 5-HT biosynthesis within taste buds. First, we verified that the rate-limiting enzyme tryptophan hydroxylase (TPH2) responsible for converting L-tryptophan into the intermediate 5-hydroxy-L-tryptophan (5-HTP) is expressed in a subset of type II taste bud cells (TBCs) whereas the enzyme aromatic L-aromatic amino acid decarboxylase (AADC) capable of converting 5-HTP into 5-HT is found in type III TBCs. And abolishment of TPH2 did not affect the production of intragemmal 5-HT or alter TBCs; the mutant mice did not show any changes in behavioral responses to all five primary taste qualities: sweet, umami, bitter, salty, and sour. Then we identified that 5-HTP as well as AADC are abundant in type III TBCs; and application of an AADC inhibitor significantly blocked the production of 5-HT in taste buds. In contrast, administration of an inhibitor on serotonin-reuptake transporters had minimal impact on the 5-HT amount in taste buds, indicating that exogenous 5-HT is not a major source for the intragemmal transmitter. Taken together, our data indicate that intragemmal serotonin is not biosynthesized de novo from tryptophan; instead, it is produced by AADC-mediated conversion of 5-HTP absorbed from the plasma and/or nerve fibers into 5-HT. Thus, our results suggest that the overall bodily 5-HTP level in the plasma and nervous system can regulate taste buds' physiological function, and provide an important molecular mechanism connecting these peripheral taste organs with the circulatory and nervous systems.
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Affiliation(s)
- Hong-Ru Pan
- Institute of Cellular and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Miao Tian
- Institute of Cellular and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Jian-Bo Xue
- Institute of Cellular and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Song-Min Li
- Institute of Cellular and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Xiao-Cui Luo
- Institute of Cellular and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Xiao Huang
- Institute of Cellular and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Zhen-Huang Chen
- Institute of Cellular and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Liquan Huang
- Institute of Cellular and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou, China
- Monell Chemical Senses Center, Philadelphia, PA, United States
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12
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Yuan Z, Ma J, Meng X, Chen N, Shen M. Chk2 deficiency alleviates irradiation-induced taste dysfunction by inhibiting p53-dependent apoptosis. Oral Dis 2018; 24:856-863. [PMID: 29292572 DOI: 10.1111/odi.12822] [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: 07/02/2017] [Revised: 12/15/2017] [Accepted: 12/21/2017] [Indexed: 01/12/2023]
Abstract
OBJECTIVE Taste dysfunction is one of the most common complications following radiotherapy, which leads to decreased appetite and life quality of patients suffering from head and neck cancer. The aim of this study was to investigate the role of checkpoint kinase 2 (Chk2) deficiency in irradiation-induced taste dysfunction. MATERIALS AND METHODS Alterations in oxidative stress, DNA damage, and potential signaling pathway were compared between Chk2-deficient (Chk2-/- ) mice and their wild-type (WT) littermates pre-irradiation and 7 and 30 days postirradiation by biochemistry and immunohistochemistry. RESULTS Chk2-/- mice showed less loss of type II and type III taste cells, lower expression of p53, caspase-3, and cleaved caspase-3, and lower apoptosis levels. However, no significant differences in H2 O2 and MDA concentrations, T-SOD and GSH-Px activities, and expression of SOD1, SOD2, and 8-OHdG were detected in the taste buds of Chk2-/- mice as compared to those of WT mice. CONCLUSION Chk2 deficiency downregulated the expression of p53 and inhibited cellular apoptosis, partly contributing to the radioprotective effect on taste cells, but did not alter oxidative stress levels, antioxidant ability, and oxidative DNA damage in taste buds.
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Affiliation(s)
- Zhiyao Yuan
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China
| | - Junchi Ma
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China
| | - Xin Meng
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China
| | - Ning Chen
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China
| | - Ming Shen
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China.,Department of Dental Implant, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
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13
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Gaillard D, Bowles SG, Salcedo E, Xu M, Millar SE, Barlow LA. β-catenin is required for taste bud cell renewal and behavioral taste perception in adult mice. PLoS Genet 2017; 13:e1006990. [PMID: 28846687 PMCID: PMC5591015 DOI: 10.1371/journal.pgen.1006990] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/08/2017] [Accepted: 08/21/2017] [Indexed: 02/07/2023] Open
Abstract
Taste stimuli are transduced by taste buds and transmitted to the brain via afferent gustatory fibers. Renewal of taste receptor cells from actively dividing progenitors is finely tuned to maintain taste sensitivity throughout life. We show that conditional β-catenin deletion in mouse taste progenitors leads to rapid depletion of progenitors and Shh+ precursors, which in turn causes taste bud loss, followed by loss of gustatory nerve fibers. In addition, our data suggest LEF1, TCF7 and Wnt3 are involved in a Wnt pathway regulatory feedback loop that controls taste cell renewal in the circumvallate papilla epithelium. Unexpectedly, taste bud decline is greater in the anterior tongue and palate than in the posterior tongue. Mutant mice with this regional pattern of taste bud loss were unable to discern sweet at any concentration, but could distinguish bitter stimuli, albeit with reduced sensitivity. Our findings are consistent with published reports wherein anterior taste buds have higher sweet sensitivity while posterior taste buds are better tuned to bitter, and suggest β-catenin plays a greater role in renewal of anterior versus posterior taste buds. By remaining relatively constant throughout adult life, the sense of taste helps keep the body healthy. However, taste perception can be disrupted by various environmental factors, including cancer therapies. Here, we show that Wnt/β-catenin signaling, a pathway known to control normal tissue maintenance and associated with the development of cancers, is required for taste cell renewal and behavioral taste sensitivity in mice. Our findings are significant as they suggest that chemotherapies targeting the Wnt pathway in cancerous tissues may cause taste dysfunction and further diminish the quality of life of patients.
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Affiliation(s)
- Dany Gaillard
- Department of Cell & Developmental Biology and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Spencer G. Bowles
- Department of Cell & Developmental Biology and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Ernesto Salcedo
- Department of Cell & Developmental Biology and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Mingang Xu
- Departments of Dermatology and Cell & Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sarah E. Millar
- Departments of Dermatology and Cell & Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Linda A. Barlow
- Department of Cell & Developmental Biology and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- * E-mail:
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14
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Abstract
Nesfatin-1, an anorexigenic peptide derived from nucleobindin 2 (NUCB2), is closely involved in feeding behavior, glycometabolism, and satiety regulation. Some studies show that NUCB2/nesfatin-1 is highly expressed and interacts with many appetite-regulating peptides that are co-expressed in the gastrointestinal tract. However, it remains unclear whether nesfatin-1 is expressed and interacts similarly in taste buds. Glucagon-like peptide-1 (GLP-1), a well-known appetite down-regulating peptide, is associated with changes in the expression of nesfatin-1. Therefore, we measured the expression of the NUCB2 gene and the distribution of nesfatin-1-immunoreactive cells and investigated whether these variables change in taste buds of circumvallate papillae (CV) from rats with type 2 diabetes (T2DM) after treatment with liraglutide, a GLP-1 receptor agonist. The results showed that nesfatin-1 immunoreactive cells were localized in the taste buds of rat CV. Quantitative RT-PCR showed a significantly lower expression of NUCB2 mRNA in the taste buds of diabetic control rats (T2DM-C) than in those of the normal control group (NC) and a higher level of NUCB2 in the liraglutide treated group (T2DM + LIR) than either the T2DM-C or the NC groups. Changes in the expression of NUCB2 in the rat hypothalamus were opposite to those in CV taste buds. In summary, we found that rat CV taste buds express NUCB2/nesfatin-1, and that this expression decreases significantly in T2DM and increases after treatment with liraglutide in rat CV. This indicates that nesfatin-1 could be an important factor in the regulation of gustatory function, feeding and perhaps energy homeostasis.
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Affiliation(s)
- Xun Cao
- Department of Endocrinology, Harbin Medical University, Harbin 150001, Heilongjiang Province, China
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15
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King BF. Purinergic signalling in the enteric nervous system (An overview of current perspectives). Auton Neurosci 2015; 191:141-7. [PMID: 26049261 DOI: 10.1016/j.autneu.2015.05.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Purinergic Signalling in the Enteric Nervous System involves the regulated release of ATP (or a structurally-related nucleotide) which activates an extensive suite of membrane-inserted receptors (P2X and P2Y subtypes) on a variety of cell types in the gastrointestinal tract. P2X receptors are gated ion-channels permeable to sodium, potassium and calcium. They depolarise cells, act as a pathway for calcium influx to activate calcium-dependent processes and initiate gene transcription, interact at a molecular level as a form of self-regulation with lipids within the cell wall (e.g. PIP2) and cross-react with other membrane-inserted receptors to regulate their activity (e.g. nAChRs). P2Y receptors are metabotropic receptors that couple to G-proteins. They may release calcium ions from intracellular stores to activate calcium-dependent processes, but also may activate calcium-independent signalling pathways and influence gene transcription. Originally ATP was a candidate only for NANC neurotransmission, for inhibitory motoneurons supplying the muscularis externa of the gastrointestinal tract and bringing about the fast IJP. Purinergic signalling later included neuron-neuron signalling in the ENS, via the production of either fast or slow EPSPs. Later still, purinergic signalling included the neuro-epithelial synapse-for efferent signalling to epithelia cells participating in secretion and absorption, and afferent signalling for chemoreception and mechanoreception at the surface of the mucosa. Many aspects of purinergic signalling have since been addressed in a series of highly-focussed and authoritative reviews. In this overview however, the current focus is on key aspects of purinergic signalling where there remains uncertainty and ambiguity, with the view to stimulating further research in these areas.
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Affiliation(s)
- Brian F King
- University College London (UCL), Department of Neuroscience, Physiology and Pharmacology (NPP), Royal Free Campus, Rowland Hill Street, Hampstead, London NW3 2PF, United Kingdom.
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16
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Abstract
In flies and humans, bitter chemicals are known to inhibit sugar detection, but the adaptive role of this inhibition is often overlooked. At best, this inhibition is described as contributing to the rejection of potentially toxic food, but no studies have addressed the relative importance of the direct pathway that involves activating bitter-sensitive cells versus the indirect pathway represented by the inhibition of sugar detection. Using toxins to selectively ablate or inactivate populations of bitter-sensitive cells, we assessed the behavioral responses of flies to sucrose mixed with strychnine (which activates bitter-sensitive cells and inhibits sugar detection) or with L-canavanine (which only activates bitter-sensitive cells). As expected, flies with ablated bitter-sensitive cells failed to detect L-canavanine mixed with sucrose in three different feeding assays (proboscis extension responses, capillary feeding, and two-choice assays). However, such flies were still able to avoid strychnine mixed with sucrose. By means of electrophysiological recordings, we established that bitter molecules differ in their potency to inhibit sucrose detection and that sugar-sensing inhibition affects taste cells on the proboscis and the legs. The optogenetic response of sugar-sensitive cells was not reduced by strychnine, thus suggesting that this inhibition is linked directly to sugar transduction. We postulate that sugar-sensing inhibition represents a mechanism in insects to prevent ingesting harmful substances occurring within mixtures.
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Yang H, Cong WN, Yoon JS, Egan JM. Vismodegib, an antagonist of hedgehog signaling, directly alters taste molecular signaling in taste buds. Cancer Med 2014; 4:245-52. [PMID: 25354792 PMCID: PMC4329008 DOI: 10.1002/cam4.350] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 08/25/2014] [Accepted: 08/25/2014] [Indexed: 12/11/2022] Open
Abstract
Vismodegib, a highly selective inhibitor of hedgehog (Hh) pathway, is an approved treatment for basal-cell carcinoma. Patients on treatment with vismodegib often report profound alterations in taste sensation. The cellular mechanisms underlying the alterations have not been studied. Sonic Hh (Shh) signaling is required for cell growth and differentiation. In taste buds, Shh is exclusively expressed in type IV taste cells, which are undifferentiated basal cells and the precursors of the three types of taste sensing cells. Thus, we investigated if vismodegib has an inhibitory effect on taste cell turnover because of its known effects on Hh signaling. We gavaged C57BL/6J male mice daily with either vehicle or 30 mg/kg vismodegib for 15 weeks. The gustatory behavior and immunohistochemical profile of taste cells were examined. Vismodegib-treated mice showed decreased growth rate and behavioral responsivity to sweet and bitter stimuli, compared to vehicle-treated mice. We found that vismodegib-treated mice had significant reductions in taste bud size and numbers of taste cells per taste bud. Additionally, vismodegib treatment resulted in decreased numbers of Ki67- and Shh-expressing cells in taste buds. The numbers of phospholipase Cβ2- and α-gustducin-expressing cells, which contain biochemical machinery for sweet and bitter sensing, were reduced in vismodegib-treated mice. Furthermore, vismodegib treatment resulted in reduction in numbers of T1R3, glucagon-like peptide-1, and glucagon-expressing cells, which are known to modulate sweet taste sensitivity. These results suggest that inhibition of Shh signaling by vismodegib treatment directly results in alteration of taste due to local effects in taste buds.
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Affiliation(s)
- Hyekyung Yang
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
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Cell mechanisms of gustatory lipids perception and modulation of the dietary fat preference. Biochimie 2014; 107 Pt A:11-4. [PMID: 24997404 DOI: 10.1016/j.biochi.2014.06.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 06/25/2014] [Indexed: 01/11/2023]
Abstract
Dietary lipids are usually responsible of several metabolic disorders. Recent compelling evidences suggest that there is a sixth taste modality, destined for the detection of oro-gustatory fats. The lipid-binding glycoprotein CD36, expressed by circumvallate papillae (CVP) of the mouse tongue, has been shown to be implicated in oro-gustatory perception of dietary lipids. We demonstrate that linoleic acid (LA) by activating sPLA2, cPLA2 and iPLA2 via CD36, produced arachidonic acid (AA) and lyso-phosphatidylcholine (Lyso-PC) which triggered Ca(2+) influx in CD36-positive taste bud cells (TBC), purified from mouse CVP. LA induced the production of Ca(2+) influx factor (CIF). CIF, AA and Lyso-PC exerted different actions on the opening of store-operated Ca2+ (SOC) channels, constituted of Orai proteins and regulated by STIM1, a sensor of Ca(2+) depletion in the endoplasmic reticulum. We observed that CIF and Lyso-PC opened Orai1 channels whereas AA-opened Ca(2+) channels were composed of Orai1/Orai3. STIM1 was found to regulate LA-induced CIF production and opening of both kinds of Ca(2+) channels. Furthermore, Stim1(-/-) mice lost the spontaneous preference for fat, observed in wild-type animals. Our results suggest that fatty acid-induced Ca(2+) signaling, regulated by STIM1 via CD36, might be implicated in oro-gustatory perception of dietary lipids and the spontaneous preference for fat. Other cell types are involved in, and external factors can influence this preference.
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Kudo KI, Kawabata F, Nomura T, Aridome A, Nishimura S, Tabata S. Isolation of chicken taste buds for real-time Ca2+imaging. Anim Sci J 2014; 85:904-9. [DOI: 10.1111/asj.12222] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 02/04/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Ken-ichi Kudo
- Department of Bioresource Sciences; Graduate School of Bioresource and Bioenvironmental Sciences; Fukuoka Japan
| | | | - Toumi Nomura
- Department of Bioresource Sciences; Graduate School of Bioresource and Bioenvironmental Sciences; Fukuoka Japan
| | - Ayumi Aridome
- Department of Bioresource Sciences; Graduate School of Bioresource and Bioenvironmental Sciences; Fukuoka Japan
| | - Shotaro Nishimura
- Department of Bioresource Sciences; Graduate School of Bioresource and Bioenvironmental Sciences; Fukuoka Japan
- Faculty of Agriculture; Kyushu University; Fukuoka Japan
| | - Shoji Tabata
- Department of Bioresource Sciences; Graduate School of Bioresource and Bioenvironmental Sciences; Fukuoka Japan
- Faculty of Agriculture; Kyushu University; Fukuoka Japan
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Gilbertson TA, Khan NA. Cell signaling mechanisms of oro-gustatory detection of dietary fat: advances and challenges. Prog Lipid Res 2013; 53:82-92. [PMID: 24269201 DOI: 10.1016/j.plipres.2013.11.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 11/08/2013] [Indexed: 01/19/2023]
Abstract
CD36 and two G-protein coupled receptors (GPCR), i.e., GPR120 and GPR40, have been implicated in the gustatory perception of dietary fats in rodents. These glycoproteins are coupled to increases in free intracellular Ca²⁺ concentrations, [Ca²⁺](i), during their activation by dietary long-chain fatty acids (LCFA). The transient receptor potential type M5 (TRPM5) channel, activated by [Ca²⁺](i), participates in downstream signaling in taste bud cells (TBC). The mice, knocked-out for expression of CD36, GPR120, GPR40 or TRPM5 have a reduced spontaneous preference for fat. The delayed rectifying K⁺ (DRK) channels believed to lie downstream of these receptors are also important players in fat taste transduction. The trigeminal neurons by triggering increases in [Ca²⁺](i) may influence the taste signal to afferent nerve fibers. Why are there so many taste receptor candidates for one taste modality? We discuss the recent advances on the role of CD36, GPR120, GPR40, TRPM5 and DRK channels, in signal transduction in TBC. We shed light on their cross-talk and delineate their roles in obesity as a better understanding of the molecular mechanisms behind their regulation could eventually lead to new strategies to fight against this condition.
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Affiliation(s)
- Timothy A Gilbertson
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA
| | - Naim A Khan
- INSERM U866, Université de Bourgogne/AgroSup, Dijon 2100, France.
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Lauri I, Pagano B, Malmendal A, Sacchi R, Novellino E, Randazzo A. Application of “magnetic tongue” to the sensory evaluation of extra virgin olive oil. Food Chem 2013; 140:692-9. [DOI: 10.1016/j.foodchem.2012.10.135] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 09/17/2012] [Accepted: 10/22/2012] [Indexed: 10/27/2022]
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Differential expression analysis throughout the weaning period in the mouse cerebral cortex. Biochem Biophys Res Commun 2013; 431:437-43. [PMID: 23333325 DOI: 10.1016/j.bbrc.2012.12.150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 12/22/2012] [Indexed: 02/05/2023]
Abstract
At weaning, mammals switch from drinking mother's milk to eating foods of environmental origin. These foods contain natural compounds with novel tastes and textures, which are provided to the young for the first time following the termination of breastfeeding. This novel eating experience may alter the cognitive brain function of mammalian babies, increasing their reactions to their food environments. Because the cerebral cortex is a central organ for cognition and learning, we investigated differences in whole-gene expression profiles in the mouse cerebral cortex using microarray analysis before and after weaning. Of 45,037 murine genes, 35 genes were upregulated and 31 genes were downregulated, in response to weaning. In particular, immediate early genes, molecular chaperones, and myelin-related genes were upregulated. In situ hybridization analysis revealed that the mRNA for an immediate early gene, Egr-2/KROX-20, was transported from the nucleus to the cell body at layer 5/6 of the somatosensory cortex during weaning. In contrast, in animals without any food supply other than mother's milk, Egr-2/KROX-20 mRNA was retained within the nucleus at the somatosensory cortex. These data suggest that the novel experience of food intake modulates gene expression profiles in the murine cerebral cortex at the weaning stage.
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23
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Gaudette NJ, Pickering GJ. Modifying Bitterness in Functional Food Systems. Crit Rev Food Sci Nutr 2013; 53:464-81. [DOI: 10.1080/10408398.2010.542511] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Romanov RA, Rogachevskaja OA, Bystrova MF, Kolesnikov SS. Electrical excitability of taste cells. Mechanisms and possible physiological significance. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2012. [DOI: 10.1134/s1990747812010126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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25
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Immunocytochemical analysis of P2X2 in rat circumvallate taste buds. BMC Neurosci 2012; 13:51. [PMID: 22621423 PMCID: PMC3507709 DOI: 10.1186/1471-2202-13-51] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/20/2012] [Indexed: 11/23/2022] Open
Abstract
Background Our laboratory has shown that classical synapses and synaptic proteins are associated with Type III cells. Yet it is generally accepted that Type II cells transduce bitter, sweet and umami stimuli. No classical synapses, however, have been found associated with Type II cells. Recent studies indicate that the ionotropic purinergic receptors P2X2/P2X3 are present in rodent taste buds. Taste nerve processes express the ionotropic purinergic receptors (P2X2/P2X3). P2X2/P2X3Dbl−/− mice are not responsive to sweet, umami and bitter stimuli, and it has been proposed that ATP acts as a neurotransmitter in taste buds. The goal of the present study is to learn more about the nature of purinergic contacts in rat circumvallate taste buds by examining immunoreactivity to antisera directed against the purinergic receptor P2X2. Results P2X2-like immunoreactivity is present in intragemmal nerve processes in rat circumvallate taste buds. Intense immunoreactivity can also be seen in the subgemmal nerve plexuses located below the basal lamina. The P2X2 immunoreactive nerve processes also display syntaxin-1-LIR. The immunoreactive nerves are in close contact with the IP3R3-LIR Type II cells and syntaxin-1-LIR and/or 5-HT-LIR Type III cells. Taste cell synapses are observed only from Type III taste cells onto P2X2-LIR nerve processes. Unusually large, “atypical” mitochondria in the Type II taste cells are found only at close appositions with P2X2-LIR nerve processes. P2X2 immunogold particles are concentrated at the membranes of nerve processes at close appositions with taste cells. Conclusions Based on our immunofluorescence and immunoelectron microscopical studies we believe that both perigemmal and most all intragemmal nerve processes display P2X2-LIR. Moreover, colloidal gold immunoelectron microscopy indicates that P2X2-LIR in nerve processes is concentrated at sites of close apposition with Type II cells. This supports the hypothesis that ATP may be a key neurotransmitter in taste transduction and that Type II cells release ATP, activating P2X2 receptors in nerve processes.
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de Araujo IE, Geha P, Small DM. Orosensory and Homeostatic Functions of the Insular Taste Cortex. CHEMOSENS PERCEPT 2012; 5:64-79. [PMID: 25485032 PMCID: PMC4254792 DOI: 10.1007/s12078-012-9117-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
The gustatory aspect of the insular cortex is part of the brain circuit that controls ingestive behaviors based on chemosensory inputs. However, the sensory properties of foods are not restricted to taste and should also include salient features such as odor, texture, temperature, and appearance. Therefore, it is reasonable to hypothesize that specialized circuits within the central taste pathways must be involved in representing several other oral sensory modalities in addition to taste. In this review, we evaluate current evidence indicating that the insular gustatory cortex functions as an integrative circuit, with taste-responsive regions also showing heightened sensitivity to olfactory, somatosensory, and even visual stimulation. We also review evidence for modulation of taste-responsive insular areas by changes in physiological state, with taste-elicited neuronal responses varying according to the nutritional state of the organism. We then examine experimental support for a functional map within the insular cortex that might reflect the various sensory and homeostatic roles associated with this region. Finally, we evaluate the potential role of the taste insular cortex in weight-gain susceptibility. Taken together, the current experimental evidence favors the view that the insular gustatory cortex functions as an orosensory integrative system that not only enables the formation of complex flavor representations but also mediates their modulation by the internal state of the body, playing therefore a central role in food intake regulation.
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Affiliation(s)
- Ivan E. de Araujo
- The John B. Pierce Laboratory, School of Medicine, Yale University, 290 Congress Avenue, New Haven, CT 06519, USA. Department of Psychiatry, School of Medicine, Yale University, 300 George Street, Suite 901, New Haven, CT 06511, USA
| | - Paul Geha
- The John B. Pierce Laboratory, School of Medicine, Yale University, 290 Congress Avenue, New Haven, CT 06519, USA. Department of Psychiatry, School of Medicine, Yale University, 300 George Street, Suite 901, New Haven, CT 06511, USA
| | - Dana M. Small
- The John B. Pierce Laboratory, School of Medicine, Yale University, 290 Congress Avenue, New Haven, CT 06519, USA. Department of Psychiatry, School of Medicine, Yale University, 300 George Street, Suite 901, New Haven, CT 06511, USA
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Rogachevskaya OA, Romanov RA, Khokhlov AA, Bystrova MF, Kolesnikov SS. Cell-to-Cell Communication in the Taste Bud: ATP and Acetylcholine as Primary Mediators. NEUROPHYSIOLOGY+ 2012. [DOI: 10.1007/s11062-012-9251-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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28
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Ferreira JG, Tellez LA, Ren X, Yeckel CW, de Araujo IE. Regulation of fat intake in the absence of flavour signalling. J Physiol 2012; 590:953-72. [PMID: 22219333 DOI: 10.1113/jphysiol.2011.218289] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Animals, including humans, can achieve precise regulation of caloric intake by adjusting consumption in response to covert changes in energy density. It remains unknown, however, whether the presence of flavour cues are required for the ability to maintain constant caloric intake. Also unknown are the brain circuits that may function as the central calorie monitors that control adaptive adjustments in energy intake. Here we show that mice trained to lick a dry spout in order to receive intra-gastric infusions of a fat emulsion maintained constant hourly caloric intake by adjusting the number of dry licks in response to changes in caloric density. Animals also increased dry licking according to hunger levels, and developed conditioned preferences for dry sippers associated with high calorie infusions. Importantly, striatal dopamine levels were closely associated with the amount of calories ingested, rather than with the number of dry licks produced. Dopamine levels in dorsal and ventral striatum also reflected caloric density in mice passively receiving intra-gastric infusions of fat emulsions. Consistent with the above, systemic administration of the dopamine receptor blocker haloperidol markedly increased the production of dry licks needed to obtain high-calorie infusions, as if the caloric density of the infusions had been diluted. Conversely, haloperidol markedly decreased the production of dry licks needed to obtain low-calorie infusions. Taken together, our results support the proposition that brain dopamine circuits function as one central sensor of calorie ingestion, since (1) extracellular striatal dopamine levels fluctuate in proportion to the caloric density of nutrients infused in the gut; and (2) inhibiting dopamine receptor signalling disrupts the animals' ability to maintain constant caloric intake across experimental sessions.
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29
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Shin YK, Cong WN, Cai H, Kim W, Maudsley S, Egan JM, Martin B. Age-related changes in mouse taste bud morphology, hormone expression, and taste responsivity. J Gerontol A Biol Sci Med Sci 2011; 67:336-44. [PMID: 22056740 DOI: 10.1093/gerona/glr192] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Normal aging is a complex process that affects every organ system in the body, including the taste system. Thus, we investigated the effects of the normal aging process on taste bud morphology, function, and taste responsivity in male mice at 2, 10, and 18 months of age. The 18-month-old animals demonstrated a significant reduction in taste bud size and number of taste cells per bud compared with the 2- and 10-month-old animals. The 18-month-old animals exhibited a significant reduction of protein gene product 9.5 and sonic hedgehog immunoreactivity (taste cell markers). The number of taste cells expressing the sweet taste receptor subunit, T1R3, and the sweet taste modulating hormone, glucagon-like peptide-1, were reduced in the 18-month-old mice. Concordant with taste cell alterations, the 18-month-old animals demonstrated reduced sweet taste responsivity compared with the younger animals and the other major taste modalities (salty, sour, and bitter) remained intact.
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Affiliation(s)
- Yu-Kyong Shin
- Laboratory of Clinical Investigation, Diabetes Section, National Institute on Aging, Baltimore, MD 21224, USA
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30
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Cholinergic chemosensory cells in the trachea regulate breathing. Proc Natl Acad Sci U S A 2011; 108:9478-83. [PMID: 21606356 DOI: 10.1073/pnas.1019418108] [Citation(s) in RCA: 217] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In the epithelium of the lower airways, a cell type of unknown function has been termed "brush cell" because of a distinctive ultrastructural feature, an apical tuft of microvilli. Morphologically similar cells in the nose have been identified as solitary chemosensory cells responding to taste stimuli and triggering trigeminal reflexes. Here we show that brush cells of the mouse trachea express the receptors (Tas2R105, Tas2R108), the downstream signaling molecules (α-gustducin, phospholipase C(β2)) of bitter taste transduction, the synthesis and packaging machinery for acetylcholine, and are addressed by vagal sensory nerve fibers carrying nicotinic acetylcholine receptors. Tracheal application of an nAChR agonist caused a reduction in breathing frequency. Similarly, cycloheximide, a Tas2R108 agonist, evoked a drop in respiratory rate, being sensitive to nicotinic receptor blockade and epithelium removal. This identifies brush cells as cholinergic sensors of the chemical composition of the lower airway luminal microenvironment that are directly linked to the regulation of respiration.
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31
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Affiliation(s)
- Albertino Bigiani
- Dipartimento di Scienze Biomediche, Sezione di Fisiologia; Università di Modena e Reggio Emilia; Modena, via G. Campi 287; 41125; Modena; Italy
| | - Simone Prandi
- Dipartimento di Scienze Biomediche, Sezione di Fisiologia; Università di Modena e Reggio Emilia; Modena, via G. Campi 287; 41125; Modena; Italy
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32
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Mathes CM, Spector AC. The selective serotonin reuptake inhibitor paroxetine does not alter consummatory concentration-dependent licking of prototypical taste stimuli by rats. Chem Senses 2011; 36:515-26. [PMID: 21422376 DOI: 10.1093/chemse/bjr011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Serotonin and the 5HT(1A) receptor are expressed in a subset of taste receptor cells, and the 5HT(3) receptor is expressed on afferent fibers innervating taste buds. Exogenous administration of the selective serotonin reuptake inhibitor, paroxetine, has been shown to increase taste sensitivity to stimuli described by humans as sweet and bitter. Serotonergic agonists also decrease food and fluid intake, and it is possible that modulations of serotonin may alter taste-based hedonic responsiveness; alternatively, or in combination, serotonin may interact with physiological state to impact ingestive behavior. In this study, the unconditioned licking of prototypical taste stimuli by rats in brief-access taste tests was assessed following paroxetine administration (0.3-10 mg/kg intraperitoneal). We also measured sucrose licking by rats in different deprivation states after paroxetine (5 mg/kg). In neither experiment did we find any evidence of an effect of paroxetine on licking relative to water to any of the taste stimuli in the brief-access test at doses that decreased food intake. However, in some conditions, paroxetine decreased trials initiated to tastants. Therefore, a systemic increase in serotonin via paroxetine administration can decrease appetitive behavior in brief-access tests but is insufficient to alter taste-guided consummatory behavior.
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Affiliation(s)
- Clare M Mathes
- Department of Psychology, Florida State University, 1107 West Call Street, PO Box 30634301, Tallahassee, FL 32306-4301, USA.
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Bitter taste receptors and α-gustducin regulate the secretion of ghrelin with functional effects on food intake and gastric emptying. Proc Natl Acad Sci U S A 2011; 108:2094-9. [PMID: 21245306 DOI: 10.1073/pnas.1011508108] [Citation(s) in RCA: 247] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Ghrelin is a hunger hormone with gastroprokinetic properties but the factors controlling ghrelin secretion from the stomach are unknown. Bitter taste receptors (T2R) and the gustatory G proteins, α-gustducin (gust) and α-transducin, are expressed in the gut and are involved in the chemosensation of nutrients. This study aimed to investigate whether T2R-agonists affect (i) ghrelin release via α-gustducin and (ii) food intake and gastric emptying via the release of ghrelin. The mouse stomach contains two ghrelin cell populations: cells containing octanoyl and desoctanoyl ghrelin, which were colocalized with α-gustducin and α-transducin, and cells staining for desoctanoyl ghrelin. Gavage of T2R-agonists increased plasma octanoyl ghrelin levels in WT mice but the effect was partially blunted in gust(-/-) mice. Intragastric administration of T2R-agonists increased food intake during the first 30 min in WT but not in gust(-/-) and ghrelin receptor knockout mice. This increase was accompanied by an increase in the mRNA expression of agouti-related peptide in the hypothalamus of WT but not of gust(-/-) mice. The temporary increase in food intake was followed by a prolonged decrease (next 4 h), which correlated with an inhibition of gastric emptying. The delay in emptying, which was partially counteracted by ghrelin, was not mediated by cholecystokinin and GLP-1 but involved a direct inhibitory effect of T2R-agonists on gastric contractility. This study is unique in providing functional evidence that activation of bitter taste receptors stimulates ghrelin secretion. Modulation of endogenous ghrelin levels by tastants may provide novel therapeutic applications for the treatment of weight -and gastrointestinal motility disorders.
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Medler KF. Multiple Roles for TRPs in the Taste System: Not Your Typical TRPs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:831-46. [DOI: 10.1007/978-94-007-0265-3_43] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Expression of GABAergic receptors in mouse taste receptor cells. PLoS One 2010; 5:e13639. [PMID: 21049022 PMCID: PMC2964312 DOI: 10.1371/journal.pone.0013639] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 10/04/2010] [Indexed: 12/05/2022] Open
Abstract
Background Multiple excitatory neurotransmitters have been identified in the mammalian taste transduction, with few studies focused on inhibitory neurotransmitters. Since the synthetic enzyme glutamate decarboxylase (GAD) for gamma-aminobutyric acid (GABA) is expressed in a subset of mouse taste cells, we hypothesized that other components of the GABA signaling pathway are likely expressed in this system. GABA signaling is initiated by the activation of either ionotropic receptors (GABAA and GABAC) or metabotropic receptors (GABAB) while it is terminated by the re-uptake of GABA through transporters (GATs). Methodology/Principal Findings Using reverse transcriptase-PCR (RT-PCR) analysis, we investigated the expression of different GABA signaling molecules in the mouse taste system. Taste receptor cells (TRCs) in the circumvallate papillae express multiple subunits of the GABAA and GABAB receptors as well as multiple GATs. Immunocytochemical analyses examined the distribution of the GABA machinery in the circumvallate papillae. Both GABAA-and GABAB- immunoreactivity were detected in the peripheral taste receptor cells. We also used transgenic mice that express green fluorescent protein (GFP) in either the Type II taste cells, which can respond to bitter, sweet or umami taste stimuli, or in the Type III GAD67 expressing taste cells. Thus, we were able to identify that GABAergic receptors are expressed in some Type II and Type III taste cells. Mouse GAT4 labeling was concentrated in the cells surrounding the taste buds with a few positively labeled TRCs at the margins of the taste buds. Conclusions/Significance The presence of GABAergic receptors localized on Type II and Type III taste cells suggests that GABA is likely modulating evoked taste responses in the mouse taste bud.
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Shin YK, Martin B, Kim W, White CM, Ji S, Sun Y, Smith RG, Sévigny J, Tschöp MH, Maudsley S, Egan JM. Ghrelin is produced in taste cells and ghrelin receptor null mice show reduced taste responsivity to salty (NaCl) and sour (citric acid) tastants. PLoS One 2010; 5:e12729. [PMID: 20856820 PMCID: PMC2939079 DOI: 10.1371/journal.pone.0012729] [Citation(s) in RCA: 79] [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: 05/12/2010] [Accepted: 08/11/2010] [Indexed: 12/14/2022] Open
Abstract
Background The gustatory system plays a critical role in determining food preferences, food intake and energy balance. The exact mechanisms that fine tune taste sensitivity are currently poorly defined, but it is clear that numerous factors such as efferent input and specific signal transduction cascades are involved. Methodology/Principal Findings Using immunohistochemical analyses, we show that ghrelin, a hormone classically considered to be an appetite-regulating hormone, is present within the taste buds of the tongue. Prepro-ghrelin, prohormone convertase 1/3 (PC 1/3), ghrelin, its cognate receptor (GHSR), and ghrelin-O-acyltransferase (GOAT , the enzyme that activates ghrelin) are expressed in Type I, II, III and IV taste cells of mouse taste buds. In addition, ghrelin and GHSR co-localize in the same taste cells, suggesting that ghrelin works in an autocrine manner in taste cells. To determine a role for ghrelin in modifying taste perception, we performed taste behavioral tests using GHSR null mice. GHSR null mice exhibited significantly reduced taste responsivity to sour (citric acid) and salty (sodium chloride) tastants. Conclusions/Significance These findings suggest that ghrelin plays a local modulatory role in determining taste bud signaling and function and could be a novel mechanism for the modulation of salty and sour taste responsivity.
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Affiliation(s)
- Yu-Kyong Shin
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Bronwen Martin
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Wook Kim
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Caitlin M. White
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Sunggoan Ji
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Yuxiang Sun
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, United States of America
| | - Roy G. Smith
- Department of Metabolism and Aging, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, United States of America
| | - Jean Sévigny
- Centre de Recherche en Rhumatologie et Immunologie, Centre Hospitalier Universitaire de Québec, Université Laval, Québec City, Québec, Canada
| | - Matthias H. Tschöp
- Division of Endocrinology, Departments of Medicine and Psychiatry, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Stuart Maudsley
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Josephine M. Egan
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
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Abstract
The central gustatory pathways are part of the brain circuits upon which rest the decision to ingest or reject a food. The quality of food stimuli, however, relies not only on their taste but also on properties such as odor, texture and temperature. We will review anatomical and functional evidence showing that the central gustatory system, in particular its cortical aspect, functions as an integrative circuit in which taste-responsive neurons also show sensitivity to somatosensory and olfactory stimulation. In addition, gustatory pathways are modulated by the internal state of the body, with neuronal responses to tastes changing according to variations in physiological parameters such as gastrointestinal hormones or blood glucose levels. Therefore, rather than working as the receptive field of peripheral taste receptor cells, the central gustatory pathways seem to operate as a multisensory system dedicated to evaluating the biological significance of intra-oral stimuli.
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Affiliation(s)
- I E de Araujo
- The John B. Pierce Laboratory & Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA.
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Murata Y, Yasuo T, Yoshida R, Obata K, Yanagawa Y, Margolskee RF, Ninomiya Y. Action potential-enhanced ATP release from taste cells through hemichannels. J Neurophysiol 2010; 104:896-901. [PMID: 20519578 DOI: 10.1152/jn.00414.2010] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Only some taste cells fire action potentials in response to sapid stimuli. Type II taste cells express many taste transduction molecules but lack well-elaborated synapses, bringing into question the functional significance of action potentials in these cells. We examined the dependence of adenosine triphosphate (ATP) transmitter release from taste cells on action potentials. To identify type II taste cells we used mice expressing a green fluorescence protein (GFP) transgene from the alpha-gustducin promoter. Action potentials were recorded by an electrode basolaterally attached to a single GFP-positive taste cell. We monitored ATP release from gustducin-expressing taste cells by collecting the electrode solution immediately after tastant-stimulated action potentials and using a luciferase assay to quantify ATP. Stimulation of gustducin-expressing taste cells with saccharin, quinine, or glutamate on the apical membrane increased ATP levels in the electrode solution; the amount of ATP depended on the firing rate. Increased spontaneous firing rates also induced ATP release from gustducin-expressing taste cells. ATP release from gustducin-expressing taste cells was depressed by tetrodotoxin and inhibited below the detection limit by carbenoxolone. Our data support the hypothesis that action potentials in taste cells responsive to sweet, bitter, or umami tastants enhance ATP release through pannexin 1, not connexin-based hemichannels.
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Affiliation(s)
- Yoshihiro Murata
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, Higashi-ku, Fukuoka, Japan
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Martin B, Shin YK, White CM, Ji S, Kim W, Carlson OD, Napora JK, Chadwick W, Chapter M, Waschek JA, Mattson MP, Maudsley S, Egan JM. Vasoactive intestinal peptide-null mice demonstrate enhanced sweet taste preference, dysglycemia, and reduced taste bud leptin receptor expression. Diabetes 2010; 59:1143-52. [PMID: 20150284 PMCID: PMC2857894 DOI: 10.2337/db09-0807] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE It is becoming apparent that there is a strong link between taste perception and energy homeostasis. Recent evidence implicates gut-related hormones in taste perception, including glucagon-like peptide 1 and vasoactive intestinal peptide (VIP). We used VIP knockout mice to investigate VIP's specific role in taste perception and connection to energy regulation. RESEARCH DESIGN AND METHODS Body weight, food intake, and plasma levels of multiple energy-regulating hormones were measured and pancreatic morphology was determined. In addition, the immunocytochemical profile of taste cells and gustatory behavior were examined in wild-type and VIP knockout mice. RESULTS VIP knockout mice demonstrate elevated plasma glucose, insulin, and leptin levels, with no islet beta-cell number/topography alteration. VIP and its receptors (VPAC1, VPAC2) were identified in type II taste cells of the taste bud, and VIP knockout mice exhibit enhanced taste preference to sweet tastants. VIP knockout mouse taste cells show a significant decrease in leptin receptor expression and elevated expression of glucagon-like peptide 1, which may explain sweet taste preference of VIP knockout mice. CONCLUSIONS This study suggests that the tongue can play a direct role in modulating energy intake to correct peripheral glycemic imbalances. In this way, we could view the tongue as a sensory mechanism that is bidirectionally regulated and thus forms a bridge between available foodstuffs and the intricate hormonal balance in the animal itself.
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Affiliation(s)
- Bronwen Martin
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Yu-Kyong Shin
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Caitlin M. White
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Sunggoan Ji
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Wook Kim
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Olga D. Carlson
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Joshua K. Napora
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Wayne Chadwick
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Megan Chapter
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - James A. Waschek
- Department of Psychiatry and Behavioral Sciences, Mental Retardation Research Center, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, California
| | - Mark P. Mattson
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Stuart Maudsley
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Josephine M. Egan
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
- Corresponding author: Josephine Egan,
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Abbate F, Guerrera MC, Montalbano G, Zichichi R, Germanà A, Ciriaco E. Morphology of the lingual dorsal surface and oral taste buds in Italian lizard (Podarcis sicula). Anat Histol Embryol 2010; 39:167-71. [PMID: 20377553 DOI: 10.1111/j.1439-0264.2010.00992.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Italian lizard (Podarcis sicula) is the most diffused reptile in Italy, but it is also present in other European countries. This lizard belongs to the Lacertidae family, lives near walls, slants and along the borders of the paths; its diet includes bugs and aracnids. No data are so far available in literature about the three-dimensional morphology of the tongue of Podarcis sicula, therefore the aim of the present paper was to study by scanning electron and light microscopy the three-dimensional characteristics of the dorsal lingual surface and moreover the presence of chemosensory receptors like the taste buds in the oral cavity. Our results demonstrate that the Podarcis sicula tongue is a triangular muscular membranous organ, dorsoventrally flattened and that three different areas can be observed: a bifid apex, a body and a root. No papillae were observed in the apex, characterized by a flattened mucosa and by two deep median pouches. In the body cylindrical papillae with a flat surface are present, aborally gradually substituted by imbricated papillae. Foliate-like papillae were observed in the lateral parts of the tongue body. No sensory structures were showed on the lingual dorsal surface, while they were numerous in the oral cavity, particularly on the gingival epithelium. The light microscopy shows, on the dorsal surface, a stratified pavimentous not keratinized epithelium, conversely keratinized along the ventral surface. Many caliciform cells on the lateral parts of the papillae, deputed to the secretion of mucus, were also observed. Therefore, the results obtained in this paper could give a contribution to the knowledge of the tongue anatomy in a species widely diffused in different European countries and could be of help for clinical purposes in reptiles.
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Affiliation(s)
- F Abbate
- Department of Morphology, Biochemistry, Physiology and Animal Production-Section of Morphology, University of Messina, Messina 98168, Italy.
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Dando R, Roper SD. Cell-to-cell communication in intact taste buds through ATP signalling from pannexin 1 gap junction hemichannels. J Physiol 2010; 587:5899-906. [PMID: 19884319 DOI: 10.1113/jphysiol.2009.180083] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Isolated taste cells, taste buds and strips of lingual tissue from taste papillae secrete ATP upon taste stimulation. Taste bud receptor (Type II) cells have been identified as the source of ATP secretion. Based on studies on isolated taste buds and single taste cells, we have postulated that ATP secreted from receptor cells via pannexin 1 hemichannels acts within the taste bud to excite neighbouring presynaptic (Type III) cells. This hypothesis, however, remains to be tested in intact tissues. In this report we used confocal Ca(2+) imaging and lingual slices containing intact taste buds to test the hypothesis of purinergic signalling between taste cells in a more integral preparation. Incubating lingual slices with apyrase reversibly blocked cell-to-cell communication between receptor cells and presynaptic cells, consistent with ATP being the transmitter. Inhibiting pannexin 1 gap junction hemichannels with CO(2)-saturated buffer or probenecid significantly reduced cell-cell signalling between receptor cells and presynaptic cells. In contrast, anandamide, a blocker of connexin gap junction channels, had no effect of cell-to-cell communication in taste buds. These findings are consistent with the model for peripheral signal processing via ATP and pannexin 1 hemichannels in mammalian taste buds.
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Affiliation(s)
- Robin Dando
- Miller School of Medicine, University of Miami Physiology & Biophysics and Program in Neuroscience, 1600 NW 10th Ave, Miami, FL 33136, USA
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Bystrova MF, Romanov RA, Rogachevskaja OA, Churbanov GD, Kolesnikov SS. Functional expression of the extracellular-Ca2+-sensing receptor in mouse taste cells. J Cell Sci 2010; 123:972-82. [PMID: 20179105 DOI: 10.1242/jcs.061879] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Three types of morphologically and functionally distinct taste cells operate in the mammalian taste bud. We demonstrate here the expression of two G-protein-coupled receptors from the family C, CASR and GPRC6A, in the taste tissue and identify transcripts for both receptors in type I cells, no transcripts in type II cells and only CASR transcripts in type III cells, by using the SMART-PCR RNA amplification method at the level of individual taste cells. Type I taste cells responded to calcimimetic NPS R-568, a stereoselective CASR probe, with Ca(2+) transients, whereas type I and type II cells were not specifically responsive. Consistent with these findings, certain amino acids stimulated PLC-dependent Ca(2+) signaling in type III cells, but not in type I and type II cells, showing the following order of efficacies: Phe~Glu>Arg. Thus, CASR is coupled to Ca(2+) mobilization solely in type III cells. CASR was cloned from the circumvallate papilla into a pIRES2-EGFP plasmid and heterologously expressed in HEK-293 cells. The transfection with CASR enabled HEK-293 cells to generate Ca(2+) transients in response to the amino acids, of which, Phe was most potent. This observation and some other facts favor CASR as the predominant receptor subtype endowing type III cells with the ability to detect amino acids. Altogether, our results indicate that type III cells can serve a novel chemosensory function by expressing the polymodal receptor CASR. A role for CASR and GPRC6A in physiology of taste cells of the type I remains to be unveiled.
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Affiliation(s)
- Marina F Bystrova
- Institute of Cell Biophysics, Russian Academy of Sciences, Institutional Street 3, Pushchino, Moscow Region, 142290, Russia
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Yoshida R, Ninomiya Y. New Insights into the Signal Transmission from Taste Cells to Gustatory Nerve Fibers. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 279:101-34. [DOI: 10.1016/s1937-6448(10)79004-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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Reception and Transmission of Taste Information in Type II and Type III Taste Bud Cells. J Oral Biosci 2010. [DOI: 10.1016/s1349-0079(10)80017-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Lee SB, Lee CH, Kim SN, Chung KM, Cho YK, Kim KN. Type II and III Taste Bud Cells Preferentially Expressed Kainate Glutamate Receptors in Rats. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2009; 13:455-60. [PMID: 20054492 PMCID: PMC2802306 DOI: 10.4196/kjpp.2009.13.6.455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 11/13/2009] [Accepted: 11/24/2009] [Indexed: 11/15/2022]
Abstract
Glutamate-induced cobalt uptake reveals that non-NMDA glutamate receptors (GluRs) are present in rat taste bud cells. Previous studies involving glutamate induced cobalt staining suggest this uptake mainly occurs via kainate type GluRs. It is not known which of the 4 types of taste bud cells express subunits of kainate GluR. Circumvallate and foliate papillae of Sprague-Dawley rats (45~60 days old) were used to search for the mRNAs of subunits of non-NMDA GluRs using RT-PCR with specific primers for GluR1-7, KA1 and KA2. We also performed RT-PCR for GluR5, KA1, PLCbeta2, and NCAM/SNAP 25 in isolated single cells from taste buds. Taste epithelium, including circumvallate or foliate papilla, express mRNAs of GluR5 and KA1. However, non-taste tongue epithelium expresses no subunits of non-NMDA GluRs. Isolated single cell RT-PCR reveals that the mRNAs of GluR5 and KA1 are preferentially expressed in Type II and Type III cells over Type I cells.
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Affiliation(s)
- Sang-Bok Lee
- Department of Physiology and Neuroscience, College of Dentistry, Gangneung-Wonju National University, Gangneung 210-702, Korea
| | - Cil-Han Lee
- Department of Physiology and Neuroscience, College of Dentistry, Gangneung-Wonju National University, Gangneung 210-702, Korea
| | - Se-Nyun Kim
- Department of Pharmacology and Mechanism, Research Institute, Oscotec Inc., Cheonan 331-831, Korea
| | - Ki-Myung Chung
- Department of Physiology and Neuroscience, College of Dentistry, Gangneung-Wonju National University, Gangneung 210-702, Korea
- Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung 210-702, Korea
| | - Young-Kyung Cho
- Department of Physiology and Neuroscience, College of Dentistry, Gangneung-Wonju National University, Gangneung 210-702, Korea
- Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung 210-702, Korea
| | - Kyung-Nyun Kim
- Department of Physiology and Neuroscience, College of Dentistry, Gangneung-Wonju National University, Gangneung 210-702, Korea
- Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung 210-702, Korea
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Abstract
The sense of taste is a specialized chemosensory system dedicated to the evaluation of food and drink. Despite the fact that vertebrates and insects have independently evolved distinct anatomic and molecular pathways for taste sensation, there are clear parallels in the organization and coding logic between the two systems. There is now persuasive evidence that tastant quality is mediated by labeled lines, whereby distinct and strictly segregated populations of taste receptor cells encode each of the taste qualities.
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Affiliation(s)
- David A. Yarmolinsky
- Department of Biochemistry and Molecular Biophysics and Department of Neuroscience, Howard Hughes Medical Institute, Columbia College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Charles S. Zuker
- Department of Biochemistry and Molecular Biophysics and Department of Neuroscience, Howard Hughes Medical Institute, Columbia College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Correspondence:
| | - Nicholas J.P. Ryba
- National Institute of Dental and Craniofacial Research (NIDCR), Bethesda, MD 20892, USA
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Abstract
The taste of sweeteners is hedonically pleasing, suggests high caloric value in food, and contributes to increased intake. In recent years, many of the molecular mechanisms underlying the detection of sweeteners have been elucidated. Of particular note is the identification of the sweet taste receptor, the heteromeric G-protein-coupled receptor T1R2:T1R3, which responds to a vast array of chemically diverse natural and artificial sweeteners. In this chapter, we discuss some of the mechanisms underlying the detection of sweeteners by mammals, with a particular focus on the function and role of the T1R2:T1R3 receptor in these processes.
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Yoshida R, Miyauchi A, Yasuo T, Jyotaki M, Murata Y, Yasumatsu K, Shigemura N, Yanagawa Y, Obata K, Ueno H, Margolskee RF, Ninomiya Y. Discrimination of taste qualities among mouse fungiform taste bud cells. J Physiol 2009; 587:4425-39. [PMID: 19622604 PMCID: PMC2766648 DOI: 10.1113/jphysiol.2009.175075] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Accepted: 07/17/2009] [Indexed: 11/08/2022] Open
Abstract
Multiple lines of evidence from molecular studies indicate that individual taste qualities are encoded by distinct taste receptor cells. In contrast, many physiological studies have found that a significant proportion of taste cells respond to multiple taste qualities. To reconcile this apparent discrepancy and to identify taste cells that underlie each taste quality, we investigated taste responses of individual mouse fungiform taste cells that express gustducin or GAD67, markers for specific types of taste cells. Type II taste cells respond to sweet, bitter or umami tastants, express taste receptors, gustducin and other transduction components. Type III cells possess putative sour taste receptors, and have well elaborated conventional synapses. Consistent with these findings we found that gustducin-expressing Type II taste cells responded best to sweet (25/49), bitter (20/49) or umami (4/49) stimuli, while all GAD67 (Type III) taste cells examined (44/44) responded to sour stimuli and a portion of them showed multiple taste sensitivities, suggesting discrimination of each taste quality among taste bud cells. These results were largely consistent with those previously reported with circumvallate papillae taste cells. Bitter-best taste cells responded to multiple bitter compounds such as quinine, denatonium and cyclohexamide. Three sour compounds, HCl, acetic acid and citric acid, elicited responses in sour-best taste cells. These results suggest that taste cells may be capable of recognizing multiple taste compounds that elicit similar taste sensation. We did not find any NaCl-best cells among the gustducin and GAD67 taste cells, raising the possibility that salt sensitive taste cells comprise a different population.
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Affiliation(s)
- Ryusuke Yoshida
- Section of Oral Neuroscience, Graduate School of Dental Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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49
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Gilbertson T, Yu T, Shah B. Gustatory Mechanisms for Fat Detection. Front Neurosci 2009. [DOI: 10.1201/9781420067767-c3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Abstract
Serotonin is perhaps best known as a neurotransmitter that modulates neural activity and a wide range of neuropsychological processes, and drugs that target serotonin receptors are used widely in psychiatry and neurology. However, most serotonin is found outside the central nervous system, and virtually all of the 15 serotonin receptors are expressed outside as well as within the brain. Serotonin regulates numerous biological processes including cardiovascular function, bowel motility, ejaculatory latency, and bladder control. Additionally, new work suggests that serotonin may regulate some processes, including platelet aggregation, by receptor-independent, transglutaminase-dependent covalent linkage to cellular proteins. We review this new "expanded serotonin biology" and discuss how drugs targeting specific serotonin receptors are beginning to help treat a wide range of diseases.
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Affiliation(s)
- Miles Berger
- Department of Psychiatry, University of California, San Francisco, California 94143, USA.
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