1
|
Chia CW, Yeager SM, Egan JM. Endocrinology of Taste with Aging. Endocrinol Metab Clin North Am 2023; 52:295-315. [PMID: 36948781 PMCID: PMC10037529 DOI: 10.1016/j.ecl.2022.10.002] [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] [Indexed: 02/18/2023]
Abstract
Taste is one of our five primary senses, and taste impairment has been shown to increase with aging. The ability to taste allows us to enjoy the food we eat and to avoid foods that are potentially spoiled or poisonous. Recent advances in our understanding of the molecular mechanisms of taste receptor cells located within taste buds help us decipher how taste works. The discoveries of "classic" endocrine hormones in taste receptor cells point toward taste buds being actual endocrine organs. A better understanding of how taste works may help in reversing taste impairment associated with aging.
Collapse
Affiliation(s)
- Chee W Chia
- Intramural Research Program, National Institute on Aging, National Institutes of Health, 3001 S. Hanover Street, 5th Floor, Room NM536, Baltimore, MD 21225, USA
| | - Shayna M Yeager
- Intramural Research Program, National Institute on Aging, National Institutes of Health, 3001 S. Hanover Street, 5th Floor, Room NM547, Baltimore, MD 21225, USA
| | - Josephine M Egan
- Intramural Research Program, National Institute on Aging, National Institutes of Health, 3001 S. Hanover Street, 5th Floor, Room NM527, Baltimore, MD 21225, USA.
| |
Collapse
|
2
|
Doyle ME, Premathilake HU, Yao Q, Mazucanti CH, Egan JM. Physiology of the tongue with emphasis on taste transduction. Physiol Rev 2023; 103:1193-1246. [PMID: 36422992 PMCID: PMC9942923 DOI: 10.1152/physrev.00012.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The tongue is a complex multifunctional organ that interacts and senses both interoceptively and exteroceptively. Although it is easily visible to almost all of us, it is relatively understudied and what is in the literature is often contradictory or is not comprehensively reported. The tongue is both a motor and a sensory organ: motor in that it is required for speech and mastication, and sensory in that it receives information to be relayed to the central nervous system pertaining to the safety and quality of the contents of the oral cavity. Additionally, the tongue and its taste apparatus form part of an innate immune surveillance system. For example, loss or alteration in taste perception can be an early indication of infection as became evident during the present global SARS-CoV-2 pandemic. Here, we particularly emphasize the latest updates in the mechanisms of taste perception, taste bud formation and adult taste bud renewal, and the presence and effects of hormones on taste perception, review the understudied lingual immune system with specific reference to SARS-CoV-2, discuss nascent work on tongue microbiome, as well as address the effect of systemic disease on tongue structure and function, especially in relation to taste.
Collapse
Affiliation(s)
- Máire E Doyle
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Hasitha U Premathilake
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Qin Yao
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Caio H Mazucanti
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Josephine M Egan
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| |
Collapse
|
3
|
Karikkineth AC, Tang EY, Kuo PL, Ferrucci L, Egan JM, Chia CW. Longitudinal trajectories and determinants of human fungiform papillae density. Aging (Albany NY) 2021; 13:24989-25003. [PMID: 34857670 PMCID: PMC8714156 DOI: 10.18632/aging.203741] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 11/23/2021] [Indexed: 01/08/2023]
Abstract
Tongue fungiform papillae contain taste buds crucial for taste and hormone-producing taste receptor cells; therefore, they may be considered as endocrine organs and have important age-associated physiological implications. We examine the cross-sectional and longitudinal trajectories of fungiform papillae density in 1084 participants from the Baltimore Longitudinal Study of Aging using linear regression models and mixed effects models. At baseline, the mean age was 67.86 ± 14.20 years, with a mean follow-up time among those with repeat visits of 4.24 ± 1.70 years. Women (53%) were younger (66.85 ± 13.78 vs. 69.04 ± 14.61 years, p < 0.001) and had a higher fungiform papillae density than men (16.14 ± 9.54 vs. 13.77 ± 8.61 papillae/cm2, p < 0.001). Whites (67%) had a lower fungiform papillae density than non-Whites after adjusting for age and sex. Factors cross-sectionally associated with a lower fungiform papillae density included a higher waist-hip ratio (β = −8.525, p = 0.029), current smoking status (β = −5.133, p = 0.014), and alcohol use within the past 12 months (β = −1.571, p = 0.025). Longitudinally, fungiform papillae density decreased linearly with follow-up time (β = −0.646, p < 0.001). The rate of decline was not affected by sex, race, BMI, waist-hip ratio, smoking, or alcohol use. The longitudinal decline of fungiform papillae density over time needs to be explored further in order to identify other possible age-associated physiological determinants.
Collapse
Affiliation(s)
- Ajoy C Karikkineth
- Clinical Core Laboratory and Biorepository, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Eric Y Tang
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Pei-Lun Kuo
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Luigi Ferrucci
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Josephine M Egan
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Chee W Chia
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| |
Collapse
|
4
|
Doyle ME, Appleton A, Liu QR, Yao Q, Mazucanti CH, Egan JM. Human Type II Taste Cells Express Angiotensin-Converting Enzyme 2 and Are Infected by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). THE AMERICAN JOURNAL OF PATHOLOGY 2021; 191:1511-1519. [PMID: 34102107 PMCID: PMC8179718 DOI: 10.1016/j.ajpath.2021.05.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 05/07/2021] [Accepted: 05/17/2021] [Indexed: 12/13/2022]
Abstract
Chemosensory changes are well-reported symptoms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The virus targets cells for entry by binding of its spike protein to cell-surface angiotensin-converting enzyme 2 (ACE2). It is not known whether ACE2 is expressed on taste receptor cells (TRCs), or whether TRCs are infected directly. in situ hybridization probe and an antibody specific to ACE2 indicated presence of ACE2 on a subpopulation of TRCs (namely, type II cells in taste buds in taste papillae). Fungiform papillae of a SARS-CoV-2+ patient exhibiting symptoms of coronavirus disease 2019 (COVID-19), including taste changes, were biopsied. Presence of replicating SARS-CoV-2 in type II cells was verified by in situ hybridization. Therefore, taste type II cells provide a potential portal for viral entry that predicts vulnerabilities to SARS-CoV-2 in the oral cavity. The continuity and cell turnover of a patient's fungiform papillae taste stem cell layer were disrupted during infection and had not completely recovered 6 weeks after symptom onset. Another patient experiencing post-COVID-19 taste disturbances also had disrupted stem cells. These results demonstrate the possibility that novel and sudden taste changes, frequently reported in COVID-19, may be the result of direct infection of taste papillae by SARS-CoV-2. This may result in impaired taste receptor stem cell activity and suggest that further work is needed to understand the acute and postacute dynamics of viral kinetics in the human taste bud.
Collapse
Affiliation(s)
- Máire E Doyle
- National Institute on Aging/Intramural Program, Baltimore Maryland.
| | - Ashley Appleton
- National Institute on Aging/Intramural Program, Baltimore Maryland
| | - Qing-Rong Liu
- National Institute on Aging/Intramural Program, Baltimore Maryland
| | - Qin Yao
- National Institute on Aging/Intramural Program, Baltimore Maryland
| | - Caio H Mazucanti
- National Institute on Aging/Intramural Program, Baltimore Maryland
| | - Josephine M Egan
- National Institute on Aging/Intramural Program, Baltimore Maryland.
| |
Collapse
|
5
|
Jang JH, Kwon O, Moon SJ, Jeong YT. Recent Advances in Understanding Peripheral Taste Decoding I: 2010 to 2020. Endocrinol Metab (Seoul) 2021; 36:469-477. [PMID: 34139798 PMCID: PMC8258330 DOI: 10.3803/enm.2021.302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/20/2021] [Indexed: 01/03/2023] Open
Abstract
Taste sensation is the gatekeeper for direct decisions on feeding behavior and evaluating the quality of food. Nutritious and beneficial substances such as sugars and amino acids are represented by sweet and umami tastes, respectively, whereas noxious substances and toxins by bitter or sour tastes. Essential electrolytes including Na+ and other ions are recognized by the salty taste. Gustatory information is initially generated by taste buds in the oral cavity, projected into the central nervous system, and finally processed to provide input signals for food recognition, regulation of metabolism and physiology, and higher-order brain functions such as learning and memory, emotion, and reward. Therefore, understanding the peripheral taste system is fundamental for the development of technologies to regulate the endocrine system and improve whole-body metabolism. In this review article, we introduce previous widely-accepted views on the physiology and genetics of peripheral taste cells and primary gustatory neurons, and discuss key findings from the past decade that have raised novel questions or solved previously raised questions.
Collapse
Affiliation(s)
- Jea Hwa Jang
- BK21 Graduate Program, Department of Biomedical Sciences, Yonsei University College of Dentistry, Seoul,
Korea
- Department of Pharmacology, Korea University College of Medicine, Yonsei University College of Dentistry, Seoul,
Korea
| | - Obin Kwon
- Departments of Biochemistry and Molecular Biology, Yonsei University College of Dentistry, Seoul,
Korea
- Biomedical Sciences, Seoul National University College of Medicine, Yonsei University College of Dentistry, Seoul,
Korea
| | - Seok Jun Moon
- Department of Oral Biology, BK21 FOUR Project, Yonsei University College of Dentistry, Seoul,
Korea
| | - Yong Taek Jeong
- BK21 Graduate Program, Department of Biomedical Sciences, Yonsei University College of Dentistry, Seoul,
Korea
- Department of Pharmacology, Korea University College of Medicine, Yonsei University College of Dentistry, Seoul,
Korea
| |
Collapse
|
6
|
Doyle ME, Appleton A, Liu QR, Yao Q, Mazucanti CH, Egan JM. Human Taste Cells Express ACE2: a Portal for SARS-CoV-2 Infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.04.21.440680. [PMID: 33907747 PMCID: PMC8077572 DOI: 10.1101/2021.04.21.440680] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Loss and changes in taste and smell are well-reported symptoms of SARS-CoV-2 infection. The virus targets cells for entry by high affinity binding of its spike protein to cell-surface angiotensin-converting enzyme- 2 (ACE2). It was not known whether ACE2 is expressed on taste receptor cells (TRCs) nor if TRCs are infected directly. Using an in-situ hybridization (ISH) probe and an antibody specific to ACE2, it seems evident that ACE2 is present on a subpopulation of specialized TRCs, namely, PLCβ2 positive, Type II cells in taste buds in taste papillae. Fungiform papillae (FP) of a SARS-CoV-2+ patient exhibiting symptoms of COVID-19, including taste changes, were biopsied. Based on ISH, replicating SARS-CoV-2 was present in Type II cells of this patient. Therefore, taste Type II cells provide a portal for viral entry that predicts vulnerabilities to SARS-CoV-2 in the oral cavity. The continuity and cell turnover of the FP taste stem cell layer of the patient were disrupted during infection and had not fully recovered 6 weeks post symptom onset. Another patient suffering post-COVID-19 taste disturbances also had disrupted stem cells. These results indicate that a COVID-19 patient who experienced taste changes had replicating virus in their taste buds and that SARS-CoV-2 infection results in deficient stem cell turnover needed for differentiation into TRCs.
Collapse
Affiliation(s)
- Máire E Doyle
- National Institute on Aging/Intramural Program, 251 Bayview Blvd, Baltimore MD 21224
| | - Ashley Appleton
- National Institute on Aging/Intramural Program, 251 Bayview Blvd, Baltimore MD 21224
| | - Qing-Rong Liu
- National Institute on Aging/Intramural Program, 251 Bayview Blvd, Baltimore MD 21224
| | - Qin Yao
- National Institute on Aging/Intramural Program, 251 Bayview Blvd, Baltimore MD 21224
| | | | - Josephine M Egan
- National Institute on Aging/Intramural Program, 251 Bayview Blvd, Baltimore MD 21224
| |
Collapse
|
7
|
An alternative pathway for sweet sensation: possible mechanisms and physiological relevance. Pflugers Arch 2020; 472:1667-1691. [PMID: 33030576 DOI: 10.1007/s00424-020-02467-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/14/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022]
Abstract
Sweet substances are detected by taste-bud cells upon binding to the sweet-taste receptor, a T1R2/T1R3 heterodimeric G protein-coupled receptor. In addition, experiments with mouse models lacking the sweet-taste receptor or its downstream signaling components led to the proposal of a parallel "alternative pathway" that may serve as metabolic sensor and energy regulator. Indeed, these mice showed residual nerve responses and behavioral attraction to sugars and oligosaccharides but not to artificial sweeteners. In analogy to pancreatic β cells, such alternative mechanism, to sense glucose in sweet-sensitive taste cells, might involve glucose transporters and KATP channels. Their activation may induce depolarization-dependent Ca2+ signals and release of GLP-1, which binds to its receptors on intragemmal nerve fibers. Via unknown neuronal and/or endocrine mechanisms, this pathway may contribute to both, behavioral attraction and/or induction of cephalic-phase insulin release upon oral sweet stimulation. Here, we critically review the evidence for a parallel sweet-sensitive pathway, involved signaling mechanisms, neural processing, interactions with endocrine hormonal mechanisms, and its sensitivity to different stimuli. Finally, we propose its physiological role in detecting the energy content of food and preparing for digestion.
Collapse
|
8
|
Rohde K, Schamarek I, Blüher M. Consequences of Obesity on the Sense of Taste: Taste Buds as Treatment Targets? Diabetes Metab J 2020; 44:509-528. [PMID: 32431111 PMCID: PMC7453985 DOI: 10.4093/dmj.2020.0058] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 03/25/2020] [Indexed: 12/19/2022] Open
Abstract
Premature obesity-related mortality is caused by cardiovascular and pulmonary diseases, type 2 diabetes mellitus, physical disabilities, osteoarthritis, and certain types of cancer. Obesity is caused by a positive energy balance due to hyper-caloric nutrition, low physical activity, and energy expenditure. Overeating is partially driven by impaired homeostatic feedback of the peripheral energy status in obesity. However, food with its different qualities is a key driver for the reward driven hedonic feeding with tremendous consequences on calorie consumption. In addition to visual and olfactory cues, taste buds of the oral cavity process the earliest signals which affect the regulation of food intake, appetite and satiety. Therefore, taste buds may play a crucial role how food related signals are transmitted to the brain, particularly in priming the body for digestion during the cephalic phase. Indeed, obesity development is associated with a significant reduction in taste buds. Impaired taste bud sensitivity may play a causal role in the pathophysiology of obesity in children and adolescents. In addition, genetic variation in taste receptors has been linked to body weight regulation. This review discusses the importance of taste buds as contributing factors in the development of obesity and how obesity may affect the sense of taste, alterations in food preferences and eating behavior.
Collapse
Affiliation(s)
- Kerstin Rohde
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Center Munich at the University of Leipzig and University Hospital Leipzig, Leipzig, Germany.
| | - Imke Schamarek
- Medical Department III (Endocrinology, Nephrology and Rheumatology), University of Leipzig, Leipzig, Germany
| | - Matthias Blüher
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Center Munich at the University of Leipzig and University Hospital Leipzig, Leipzig, Germany.
- Medical Department III (Endocrinology, Nephrology and Rheumatology), University of Leipzig, Leipzig, Germany
| |
Collapse
|
9
|
Mazucanti CH, Liu QR, Lang D, Huang N, O’Connell JF, Camandola S, Egan JM. Release of insulin produced by the choroid plexis is regulated by serotonergic signaling. JCI Insight 2019; 4:131682. [PMID: 31647782 PMCID: PMC6962018 DOI: 10.1172/jci.insight.131682] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 10/16/2019] [Indexed: 12/21/2022] Open
Abstract
The choroid plexus (ChP) is a highly vascularized tissue found in the brain ventricles, with an apical epithelial cell layer surrounding fenestrated capillaries. It is responsible for the production of most of the cerebrospinal fluid (CSF) in the ventricular system, subarachnoid space, and central canal of the spinal cord, while also constituting the blood-CSF barrier (BCSFB). In addition, epithelial cells of the ChP (EChP) synthesize neurotrophic factors and other signaling molecules that are released into the CSF. Here, we show that insulin is produced in EChP of mice and humans, and its expression and release are regulated by serotonin. Insulin mRNA and immune-reactive protein, including C-peptide, are present in EChP, as detected by several experimental approaches, and appear in much higher levels than any other brain region. Moreover, insulin is produced in primary cultured mouse EChP, and its release, albeit Ca2+ sensitive, is not regulated by glucose. Instead, activation of the 5HT2C receptor by serotonin treatment led to activation of IP3-sensitive channels and Ca2+ mobilization from intracellular storage, leading to insulin secretion. In vivo depletion of brain serotonin in the dorsal raphe nucleus negatively affected insulin expression in the ChP, suggesting an endogenous modulation of ChP insulin by serotonin. Here, we show for the first time to our knowledge that insulin is produced by EChP in the brain, and its release is modulated at least by serotonin but not glucose.
Collapse
|
10
|
Takai S, Watanabe Y, Sanematsu K, Yoshida R, Margolskee RF, Jiang P, Atsuta I, Koyano K, Ninomiya Y, Shigemura N. Effects of insulin signaling on mouse taste cell proliferation. PLoS One 2019; 14:e0225190. [PMID: 31714935 PMCID: PMC6850543 DOI: 10.1371/journal.pone.0225190] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 10/30/2019] [Indexed: 12/26/2022] Open
Abstract
Expression of insulin and its receptor (IR) in rodent taste cells has been proposed, but exactly which types of taste cells express IR and the function of insulin signaling in taste organ have yet to be determined. In this study, we analyzed expression of IR mRNA and protein in mouse taste bud cells in vivo and explored its function ex vivo in organoids, using RT-PCR, immunohistochemistry, and quantitative PCR. In mouse taste tissue, IR was expressed broadly in taste buds, including in type II and III taste cells. With using 3-D taste bud organoids, we found insulin in the culture medium significantly decreased the number of taste cell and mRNA expression levels of many taste cell genes, including nucleoside triphosphate diphosphohydrolase-2 (NTPDase2), Tas1R3 (T1R3), gustducin, carbonic anhydrase 4 (CA4), glucose transporter-8 (GLUT8), and sodium-glucose cotransporter-1 (SGLT1) in a concentration-dependent manner. Rapamycin, an inhibitor of mechanistic target of rapamycin (mTOR) signaling, diminished insulin's effects and increase taste cell generation. Altogether, circulating insulin might be an important regulator of taste cell growth and/or proliferation via activation of the mTOR pathway.
Collapse
Affiliation(s)
- Shingo Takai
- Section of Oral Neuroscience, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
- Monell Chemical Senses Center, Philadelphia, PA, United States of America
- * E-mail: (ST); (NS)
| | - Yu Watanabe
- Section of Oral Neuroscience, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
- Section of Removable Prosthodontics, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Keisuke Sanematsu
- Section of Oral Neuroscience, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Ryusuke Yoshida
- Department of Oral Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | | | - Peihua Jiang
- Monell Chemical Senses Center, Philadelphia, PA, United States of America
| | - Ikiru Atsuta
- Section of Removable Prosthodontics, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Kiyoshi Koyano
- Section of Removable Prosthodontics, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Yuzo Ninomiya
- Monell Chemical Senses Center, Philadelphia, PA, United States of America
- Division of Sensory Physiology, Research and Development Center for Five-Sense Devices Taste and Odor Sensing, Kyushu University, Fukuoka, Japan
| | - Noriatsu Shigemura
- Section of Oral Neuroscience, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
- Division of Sensory Physiology, Research and Development Center for Five-Sense Devices Taste and Odor Sensing, Kyushu University, Fukuoka, Japan
- * E-mail: (ST); (NS)
| |
Collapse
|
11
|
Chia CW, Egan JM. Incretins in obesity and diabetes. Ann N Y Acad Sci 2019; 1461:104-126. [PMID: 31392745 PMCID: PMC10131087 DOI: 10.1111/nyas.14211] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/13/2019] [Accepted: 07/18/2019] [Indexed: 12/11/2022]
Abstract
Incretins are hormones secreted from enteroendocrine cells after nutrient intake that stimulate insulin secretion from β cells in a glucose-dependent manner. Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are the only two known incretins. Dysregulation of incretin secretion and actions are noted in diseases such as obesity and diabetes. In this review, we first summarize our traditional understanding of the physiology of GIP and GLP-1, and our current knowledge of the relationships between GIP and GLP-1 and obesity and diabetes. Next, we present the results from major randomized controlled trials on the use of GLP-1 receptor agonists for managing type 2 diabetes, and emerging data on treating obesity and prediabetes. We conclude with a glimpse of the future with possible complex interactions between nutrients, gut microbiota, the endocannabinoid system, and enteroendocrine cells.
Collapse
Affiliation(s)
- Chee W Chia
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Josephine M Egan
- Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| |
Collapse
|
12
|
Hishimoto A, Pletnikova O, Lang DL, Troncoso JC, Egan JM, Liu QR. Neurexin 3 transmembrane and soluble isoform expression and splicing haplotype are associated with neuron inflammasome and Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2019; 11:28. [PMID: 30902061 PMCID: PMC6429815 DOI: 10.1186/s13195-019-0475-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 02/17/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND Synaptic damage precedes neuron death in Alzheimer's disease (AD). Neurexins, NRXN1, NRXN2, and NRXN3, are presynaptic adhesion molecules that specify neuron synapses and regulate neurotransmitter release. Neurexins and postsynaptic neuroligins interact with amyloid beta oligomer (AβO) deposits in damaged synapses. NRXN3 gene variants have been associated with autism, addiction, and schizophrenia, however, not fully investigated in Alzheimer's disease. In the present study, we investigated an AD association of a 3'-splicing allele of rs8019381 that produces altered expression of transmembrane or soluble NRXN3 isoforms. METHODS We carried out RT-PCR (reverse transcription polymerase chain reaction), PCR-RFLP (PCR and restriction fragment length polymorphism), Sanger sequencing, and in situ hybridization (ISH) assays for NRXN3 neuron expression and genotyping. Genetic associations were analyzed by χ2 tests, and ISH signals were analyzed by FISH v1.0 module of Indica Labs HALO software. RESULTS We previously identified a functional haplotype in the 3' region of neurexin 3 (NRXN3) gene that alters the expression ratios between NRXN3 transmembrane and soluble isoforms. In this study, we found that expression and ratio of transmembrane and soluble NRXN3 isoforms were reduced in AD postmortem brains and inversely correlated with inflammasome component NLRP3 in AD brain regions. The splicing haplotype related to the transmembrane and soluble NRXN3 expression was associated with AD samples with P = 6.3 × 10-5 (odds ratio = 2.48) and interacted with APOE genotypes. CONCLUSIONS We found that the SNP rs8019381 of NRXN3 that is located adjacent to splicing site #5 (SS#5) interacts with the APOE ε4 haplotype and alters NRXN3 transmembrane or soluble isoform expression in AD postmortem cortex. Dysregulation of presynaptic NRXN3 expression and splicing might increase neuron inflammation in AD brain.
Collapse
Affiliation(s)
- Akitoyo Hishimoto
- Department of Psychiatry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-Cho, Chuo-Ku, Kobe, 650-0017, Japan
| | - Olga Pletnikova
- Departments of Pathology, Neuropathology Division, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Doyle Lu Lang
- Lab of Clinical Investigation, NIA-NIH, 251 Bayview Blvd, Baltimore, MD, 21224, USA
| | - Juan C Troncoso
- Departments of Pathology, Neuropathology Division, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Josephine M Egan
- Lab of Clinical Investigation, NIA-NIH, 251 Bayview Blvd, Baltimore, MD, 21224, USA
| | - Qing-Rong Liu
- Lab of Clinical Investigation, NIA-NIH, 251 Bayview Blvd, Baltimore, MD, 21224, USA.
| |
Collapse
|
13
|
Behrens M, Meyerhof W. A role for taste receptors in (neuro)endocrinology? J Neuroendocrinol 2019; 31:e12691. [PMID: 30712315 DOI: 10.1111/jne.12691] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/14/2019] [Accepted: 01/29/2019] [Indexed: 12/12/2022]
Abstract
The sense of taste is positioned at the forefront when it comes to the interaction of our body with foodborne chemicals. However, the role of our taste system, and in particular its associated taste receptors, is not limited to driving food preferences leading to ingestion or rejection before other organs take over responsibility for nutrient digestion, absorption and metabolic regulation. Taste sensory elements do much more. On the one hand, extra-oral taste receptors from the brain to the gut continue to sense nutrients and noxious substances after ingestion and, on the other hand, the nutritional state feeds back on the taste system. This intricate regulatory network is orchestrated by endocrine factors that are secreted in response to taste receptor signalling and, in turn regulate the taste receptor cells themselves. The present review summarises current knowledge on the endocrine regulation of the taste perceptual system and the release of hunger/satiety regulating factors by gastrointestinal taste receptors. Furthermore, the regulation of blood glucose levels via the activation of pancreatic sweet taste receptors and subsequent insulin secretion, as well as the influence of bitter compounds on thyroid hormone release, is addressed. Finally, the central effects of tastants are discussed briefly.
Collapse
Affiliation(s)
- Maik Behrens
- Leibniz-Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Wolfgang Meyerhof
- Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| |
Collapse
|
14
|
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]
|