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Baidoo N, Sanger GJ. The human colon: Evidence for degenerative changes during aging and the physiological consequences. Neurogastroenterol Motil 2024:e14848. [PMID: 38887160 DOI: 10.1111/nmo.14848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 04/16/2024] [Accepted: 06/05/2024] [Indexed: 06/20/2024]
Abstract
BACKGROUND The incidence of constipation increases among the elderly (>65 years), while abdominal pain decreases. Causes include changes in lifestyle (e.g., diet and reduced exercise), disease and medications affecting gastrointestinal functions. Degenerative changes may also occur within the colo-rectum. However, most evidence is from rodents, animals with relatively high rates of metabolism and accelerated aging, with considerable variation in time course. In humans, cellular and non-cellular changes in the aging intestine are poorly investigated. PURPOSE To examine all available studies which reported the effects of aging on cellular and tissue functions of human isolated colon, noting the region studied, sex and age of tissue donors and study size. The focus on human colon reflects the ability to access full-thickness tissue over a wide age range, compared with other gastrointestinal regions. Details are important because of natural human variability. We found age-related changes within the muscle, in the enteric and nociceptor innervation, and in the submucosa. Some involve all regions of colon, but the ascending colon appears more vulnerable. Changes can be cell- and sublayer-dependent. Mechanisms are unclear but may include development of "senescent-like" and associated inflammaging, perhaps associated with increased mucosal permeability to harmful luminal contents. In summary, reduced nociceptor innervation can explain diminished abdominal pain among the elderly. Degenerative changes within the colon wall may have little impact on symptoms and colonic functions, because of high "functional reserve," but are likely to facilitate the development of constipation during age-related challenges (e.g., lifestyle, disease, and medications), now operating against a reduced functional reserve.
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Affiliation(s)
- Nicholas Baidoo
- School of Life Sciences, University of Westminster, London, UK
- Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Gareth J Sanger
- Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Collier CA, Foncerrada S, Clevenger AJ, Shetty A, Raghavan SA. Acute Exposure to Pyridostigmine Bromide Disrupts Cholinergic Myenteric Neuroimmune Function in Mice. Adv Biol (Weinh) 2023; 7:e2200254. [PMID: 36802210 DOI: 10.1002/adbi.202200254] [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: 09/15/2022] [Revised: 11/30/2022] [Indexed: 02/21/2023]
Abstract
Gulf War Illness (GWI) results from chemical exposure during the Gulf War, with notable impacts on gastrointestinal motility. Due to the limited demographic impacted by this ailment, an in-depth investigation of the GWI has yielded little regarding the underlying pathophysiological mechanisms. Here, the hypothesis that exposure to pyridostigmine bromide (PB) results in severe enteric neuro-inflammation, that cascades to disruptions in colonic motility, is tested. The analyses are performed on male C57BL/6 mice that are treated with physiologically similar doses of PB given to GW veterans. When colonic motility is assessed, GWI colons have significantly reduced forces in response to acetylcholine or electrical field stimulation. GWI is also accompanied by high levels of pro-inflammatory cytokines and chemokines, associated with increased numbers of CD40+ pro-inflammatory macrophages within the myenteric plexus. Enteric neurons responsible for mediating colonic motility reside within the myenteric plexus, and PB exposure reduced their numbers. Significant smooth muscle hypertrophy is also observed due to increased inflammation. Together, the results show that PB exposure caused functional and anatomical dysfunction, promoting impaired motility within the colon. Achieving a greater understanding of the mechanisms of GWI will allow more refinement in therapeutic options that improve veterans' quality of life.
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Affiliation(s)
- Claudia A Collier
- Department of Biomedical Engineering, College of Engineering, Texas A&M University, 3120 TAMU, College Station, TX, 77843, USA
| | - Steven Foncerrada
- Department of Biomedical Engineering, College of Engineering, Texas A&M University, 3120 TAMU, College Station, TX, 77843, USA
| | - Abigail J Clevenger
- Department of Biomedical Engineering, College of Engineering, Texas A&M University, 3120 TAMU, College Station, TX, 77843, USA
| | - Ashok Shetty
- Department of Cell Biology and Genetics, School of Medicine, Texas A&M University, 8447 Riverside Pkwy, Bryan, College Station, TX, 77807, USA
| | - Shreya A Raghavan
- Department of Biomedical Engineering, College of Engineering, Texas A&M University, 3120 TAMU, College Station, TX, 77843, USA
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Crnčević N, Hukić M, Deumić S, Selimagić A, Dozić A, Gavrankapetanović I, Klepo D, Avdić M. Gastrointestinal Tract Microbiome Effect and Role in Disease Development. Diseases 2022; 10:diseases10030045. [PMID: 35892739 PMCID: PMC9326677 DOI: 10.3390/diseases10030045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/17/2022] [Accepted: 07/05/2022] [Indexed: 02/01/2023] Open
Abstract
In recent years, it has been shown that gastrointestinal microflora has a substantial impact on the development of a large number of chronic diseases. The imbalance in the number or type of microbes in the gastrointestinal tract can lead to diseases and conditions, including autism spectrum disorder, celiac disease, Crohn’s disease, diabetes, and small bowel cancers. This can occur as a result of genetics, alcohol, tobacco, chemotherapeutics, cytostatics, as well as antibiotic overuse. Due to this, essential taxa can be lost, and the host’s metabolism can be severely affected. A less known condition called small intestine bacterial overgrowth (SIBO) can be seen in patients who suffer from hypochlorhydria and small intestine cancers. It is characterized as a state in which the bacterial population in the small intestine exceeds 105–106 organisms/mL. The latest examination methods such as double-balloon enteroscopy and wireless capsule endoscopy have the potential to increase the accuracy and precision of diagnosis and provide better patient care. This review paper aims to summarize the effect of the gastrointestinal environment on chronic disease severity and the development of cancers.
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Affiliation(s)
- Neira Crnčević
- Department of Genetics and Bioengineering, International Burch University, Francuske revolucije bb, Ilidža, 71210 Sarajevo, Bosnia and Herzegovina; (S.D.); (D.K.); (M.A.)
- Correspondence: ; Tel.: +387-61-034-487
| | - Mirsada Hukić
- Academy of Sciences and Arts of Bosnia and Herzegovina, Center for Disease Control and Geohealth Studies, Bistrik 7, 71000 Sarajevo, Bosnia and Herzegovina;
- Institute for Biomedical Diagnostics and Research Nalaz, Čekaluša 69, 71000 Sarajevo, Bosnia and Herzegovina
| | - Sara Deumić
- Department of Genetics and Bioengineering, International Burch University, Francuske revolucije bb, Ilidža, 71210 Sarajevo, Bosnia and Herzegovina; (S.D.); (D.K.); (M.A.)
| | - Amir Selimagić
- Department of Gastroenterohepatology, General Hospital “Prim. dr. Abdulah Nakas”, 71000 Sarajevo, Bosnia and Herzegovina;
| | - Ada Dozić
- Department of Internal Medicine, General Hospital “Prim. dr. Abdulah Nakas”, 71000 Sarajevo, Bosnia and Herzegovina;
| | - Ismet Gavrankapetanović
- University Clinical Center Sarajevo, Clinic of Orthopedics and Traumatology, Bolnička 25, 71000 Sarajevo, Bosnia and Herzegovina;
| | - Dženana Klepo
- Department of Genetics and Bioengineering, International Burch University, Francuske revolucije bb, Ilidža, 71210 Sarajevo, Bosnia and Herzegovina; (S.D.); (D.K.); (M.A.)
| | - Monia Avdić
- Department of Genetics and Bioengineering, International Burch University, Francuske revolucije bb, Ilidža, 71210 Sarajevo, Bosnia and Herzegovina; (S.D.); (D.K.); (M.A.)
- Academy of Sciences and Arts of Bosnia and Herzegovina, Center for Disease Control and Geohealth Studies, Bistrik 7, 71000 Sarajevo, Bosnia and Herzegovina;
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Palmer A, Epton S, Crawley E, Straface M, Gammon L, Edgar MM, Xu Y, Elahi S, Chin-Aleong J, Martin JE, Bishop CL, Knowles CH, Sanger GJ. Expression of p16 Within Myenteric Neurons of the Aged Colon: A Potential Marker of Declining Function. Front Neurosci 2021; 15:747067. [PMID: 34690683 PMCID: PMC8529329 DOI: 10.3389/fnins.2021.747067] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/14/2021] [Indexed: 01/31/2023] Open
Abstract
Human colonic neuromuscular functions decline among the elderly. The aim was to explore the involvement of senescence. A preliminary PCR study looked for age-dependent differences in expression of CDKN1A (encoding the senescence-related p21 protein) and CDKN2A (encoding p16 and p14) in human ascending and descending colon (without mucosa) from 39 (approximately 50: 50 male: female) adult (aged 27–60 years) and elderly donors (70–89 years). Other genes from different aging pathways (e.g., inflammation, oxidative stress, autophagy) and cell-types (e.g., neurons, neuron axonal transport) were also examined. Unlike CDKN1A, CDKN2A (using primers for p16 and p14 but not when using p14-specific primers) was upregulated in both regions of colon. Compared with the number of genes appearing to upregulate in association with temporal age, more genes positively associated with increased CDKN2A expression (respectively, 16 and five of 44 genes studied for ascending and descending colon). Confirmation of increased expression of CDKN2A was sought by immunostaining for p16 in the myenteric plexus of colon from 52 patients, using a semi-automated software protocol. The results showed increased staining not within the glial cells (S100 stained), but in the cytoplasm of myenteric nerve cell bodies (MAP2 stained, with identified nucleus) of ascending, but not descending colon of the elderly, and not in the cell nucleus of either region or age group (5,710 neurons analyzed: n = 12–14 for each group). It was concluded that increased p16 staining within the cytoplasm of myenteric nerve cell bodies of elderly ascending (but not descending) colon, suggests a region-dependent, post-mitotic cellular senescence-like activity, perhaps involved with aging of enteric neurons within the colon.
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Affiliation(s)
- Alexandra Palmer
- Center for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Sarah Epton
- Barts Health NHS Trust, Department of Colorectal Surgery and Pathology, The Royal London Hospital, London, United Kingdom
| | - Ellie Crawley
- Center for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Marilisa Straface
- Center for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Luke Gammon
- Center for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Meghan M Edgar
- Gastroenterology Drug Discovery Unit, Takeda Pharmaceuticals, San Diego, CA, United States
| | - Yichen Xu
- Center for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Shezan Elahi
- Center for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Joanne Chin-Aleong
- Barts Health NHS Trust, Department of Colorectal Surgery and Pathology, The Royal London Hospital, London, United Kingdom
| | - Joanne E Martin
- Center for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.,Barts Health NHS Trust, Department of Colorectal Surgery and Pathology, The Royal London Hospital, London, United Kingdom
| | - Cleo L Bishop
- Center for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.,Center for Inflammation and Therapeutic Innovation Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Charles H Knowles
- Center for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.,Barts Health NHS Trust, Department of Colorectal Surgery and Pathology, The Royal London Hospital, London, United Kingdom
| | - Gareth J Sanger
- Center for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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Zhao A, Wang MC, Szeto IMY, Meng LP, Wang Y, Li T, Zhang YM. Gastrointestinal discomforts and dietary intake in Chinese urban elders: A cross-sectional study in eight cities of China. World J Gastroenterol 2019; 25:6681-6692. [PMID: 31832006 PMCID: PMC6906206 DOI: 10.3748/wjg.v25.i45.6681] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 10/24/2019] [Accepted: 11/13/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Gastrointestinal (GI) discomforts are common in the elderly population; however, whether such discomforts are associated with dietary intake has not been studied.
AIM To evaluate GI discomforts in Chinese urban elders and the associated factors.
METHODS The gastrointestinal symptom rating scale (GSRS) was used to identify GI discomforts in 688 elders from eight cities of China. The semi-quantitative food frequency questionnaire and one time of 24 h dietary recall were used to access the food intake, identify dietary pattern, and calculate the nutrients intake.
RESULTS About 83% of studied elders experienced at least one of GI discomforts in the past 6 mo; dyspepsia was the most commonly reported (66.7%), followed by reflux (44.8%), abdominal pain (35.9%), constipation (35.8%), and diarrhea (34.7%). Female gender, lower education level, and lower family income were associated with a higher GSRS score. Participants who were diagnosed with a GI-related disease had a higher score of constipation, but a lower score of reflux. Chronic diseases were positively associated with certain GI discomforts. Three dietary patterns were identified by the method of principal component analysis, which were characterized as high intake of salt and tea; more frequent intake of tubers, fruits, aquatic products, and soybeans; and high intake of cereal, vegetables, and meat, respectively. However, no associations between dietary patterns and GSRS score were found. The elders with a higher GSRS score had significantly lower intake of bean products. The elders whose GSRS score was ≥ 21 and 18-20 decreased their bean production intake by 7.2 (0.3, 14.3) g/d and 14.3 (1.2, 27.3) g/d, respectively, compared with those who had a GSRS score ≤ 17. There were no differences in other food categories, calories, or nutrients intake among elders with different GSRS scores.
CONCLUSION GI discomforts are common in Chinese urban elders. GI discomforts might be associated with the choice of food.
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Affiliation(s)
- Ai Zhao
- School of Public Health, Peking University, Beijing 100191, China
| | - Mei-Chen Wang
- School of Public Health, Peking University, Beijing 100191, China
| | - Ignatius Man-Yau Szeto
- Yili Innovation Center, Inner Mongolia Yili Industrial Group Co., Ltd., Hohhot 010110, Inner Mongolia Autonomous Region, China
- Inner Mongolia Dairy Technology Research Institute Co., Ltd., Hohhot 010110, Inner Mongolia Autonomous Region, China
| | - Li-Ping Meng
- Yili Innovation Center, Inner Mongolia Yili Industrial Group Co., Ltd., Hohhot 010110, Inner Mongolia Autonomous Region, China
- Inner Mongolia Dairy Technology Research Institute Co., Ltd., Hohhot 010110, Inner Mongolia Autonomous Region, China
| | - Yan Wang
- Yili Innovation Center, Inner Mongolia Yili Industrial Group Co., Ltd., Hohhot 010110, Inner Mongolia Autonomous Region, China
- Inner Mongolia Dairy Technology Research Institute Co., Ltd., Hohhot 010110, Inner Mongolia Autonomous Region, China
| | - Ting Li
- Yili Innovation Center, Inner Mongolia Yili Industrial Group Co., Ltd., Hohhot 010110, Inner Mongolia Autonomous Region, China
- Inner Mongolia Dairy Technology Research Institute Co., Ltd., Hohhot 010110, Inner Mongolia Autonomous Region, China
| | - Yu-Mei Zhang
- School of Public Health, Peking University, Beijing 100191, China
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Fidalgo S, Patel BA, Ranson RN, Saffrey MJ, Yeoman MS. Changes in murine anorectum signaling across the life course. Neurogastroenterol Motil 2018; 30:e13426. [PMID: 30062757 PMCID: PMC6175477 DOI: 10.1111/nmo.13426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 06/18/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND Increasing age is associated with an increase in the incidence of chronic constipation and fecal impaction. The contribution of the natural aging process to these conditions is not fully understood. This study examined the effects of increasing age on the function of the murine anorectum. METHODS The effects of increasing age on cholinergic, nitrergic, and purinergic signaling pathways in the murine anorectum were examined using classical organ bath assays to examine tissue function and electrochemical sensing to determine age-related changes in nitric oxide and acetylcholine release. KEY RESULTS Nitrergic relaxation increased between 3 and 6 months, peaked at 12 months and declined in the 18 and 24 months groups. These changes were in part explained by an age-related decrease in nitric oxide (NO) release. Cholinergic signaling was maintained with age by an increase in acetylcholine (ACh) release and a compensatory decrease in cholinesterase activity. Age-related changes in purinergic relaxation were qualitatively similar to nitrergic relaxation although the relaxations were much smaller. Increasing age did not alter the response of the anorectum smooth muscle to exogenously applied ACh, ATP, sodium nitroprusside or KCl. Similarly, there was no change in basal tension developed by the anorectum. CONCLUSIONS AND INFERENCES The decrease in nitrergic signaling with increasing age may contribute to the age-related fecal impaction and constipation previously described in this model by partially obstructing defecation.
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Affiliation(s)
- S. Fidalgo
- School of Pharmacy and Biomolecular ScienceCentre for Stress and Age‐Related DiseaseUniversity of BrightonBrightonUK
| | - B. A. Patel
- School of Pharmacy and Biomolecular ScienceCentre for Stress and Age‐Related DiseaseUniversity of BrightonBrightonUK
| | - R. N. Ranson
- Department of Applied SciencesFaculty of Health and Life SciencesNorthumbria UniversityNewcastle upon TyneUK
| | - M. J. Saffrey
- School of Life, Health and Chemical SciencesThe Open UniversityMilton KeynesUK
| | - M. S. Yeoman
- School of Pharmacy and Biomolecular ScienceCentre for Stress and Age‐Related DiseaseUniversity of BrightonBrightonUK
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The influence of experimental inflammation and axotomy on leucine enkephalin (leuENK) distribution in intramural nervous structures of the porcine descending colon. BMC Vet Res 2018; 14:169. [PMID: 29793486 PMCID: PMC5968568 DOI: 10.1186/s12917-018-1496-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 05/14/2018] [Indexed: 12/13/2022] Open
Abstract
Background The enteric nervous system (ENS), located in the intestinal wall and characterized by considerable independence from the central nervous system, consists of millions of cells. Enteric neurons control the majority of functions of the gastrointestinal tract using a wide range of substances, which are neuromediators and/or neuromodulators. One of them is leucine–enkephalin (leuENK), which belongs to the endogenous opioid family. It is known that opioids in the gastrointestinal tract have various functions, including visceral pain conduction, intestinal motility and secretion and immune processes, but many aspects of distribution and function of leuENK in the ENS, especially during pathological states, remain unknown. Results During this experiment, the distribution of leuENK – like immunoreactive (leuENK-LI) nervous structures using the immunofluorescence technique were studied in the porcine colon in physiological conditions, during chemically-induced inflammation and after axotomy. The study included the circular muscle layer, myenteric (MP), outer submucous (OSP) and inner submucous plexus (ISP) and the mucosal layer. In control animals, the number of leuENK-LI neurons amounted to 4.86 ± 0.17%, 2.86 ± 0.28% and 1.07 ± 0.08% in the MP, OSP and ISP, respectively. Generally, both pathological stimuli caused an increase in the number of detected leuENK-LI cells, but the intensity of the observed changes depended on the factor studied and part of the ENS. The percentage of leuENK-LI perikarya amounted to 11.48 ± 0.96%, 8.71 ± 0.13% and 9.40 ± 0.76% during colitis, and 6.90 ± 0.52% 8.46 ± 12% and 4.48 ± 0.44% after axotomy in MP, OSP and ISP, respectively. Both processes also resulted in an increase in the number of leuENK-LI nerves in the circular muscle layer, whereas changes were less visible in the mucosa during inflammation and axotomy did not change the number of leuENK-LI mucosal fibers. Conclusions LeuENK in the ENS takes part in intestinal regulatory processes not only in physiological conditions, but also under pathological factors. The observed changes are probably connected with the participation of leuENK in sensory and motor innervation and the neuroprotective effects of this substance. Differences in the number of leuENK-LI neurons during inflammation and after axotomy may suggest that the exact functions of leuENK probably depend on the type of pathological factor acting on the intestine.
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Nanayakkara WS, Gearry RB, Muir JG, O'Brien L, Wilkinson TJ, Williman JA, Skidmore PML. Gastrointestinal Symptoms and FODMAP Intake of Aged-Care Residents from Christchurch, New Zealand. Nutrients 2017; 9:nu9101083. [PMID: 28961170 PMCID: PMC5691700 DOI: 10.3390/nu9101083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/21/2017] [Accepted: 09/21/2017] [Indexed: 12/18/2022] Open
Abstract
Studies on fermentable oligo-, di-, and monosaccharides as well as polyols (FODMAPs) intake in older adults are lacking. This study investigated the relationship between gastrointestinal (GI) symptoms and FODMAPs in aged care residents. The Gastrointestinal Symptom Rating Score questionnaire modified for patients with IBS (GSRS-IBS) was used to identify participants with IBS-like symptoms. Dietary intake was assessed for a subgroup of participants with highest total GSRS-IBS score (symptomatic cases) and age, sex, and level of care matched participants with low total GSRS-IBS score (asymptomatic controls). Seventy-four participants with a mean (SD) age of 86 (6.6) years completed the GSRS-IBS questionnaire and dietary data were collected using food diaries from a subsample of 27 symptomatic and 27 asymptomatic participants. The study found many older adults with functional gut symptoms. There were no differences between the groups for FODMAP intake and no significant relationship was found between FODMAP intake and total GSRS-IBS score. Lactose from milk and milk-based desserts was the biggest FODMAP contributor (16 g/day) and a significant relationship between total FODMAP intake and diarrhoea was found. A larger study sample in future studies is required to better capture symptomatic cases and manipulation of dietary FODMAPs may assist with the management of IBS in the elderly.
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Affiliation(s)
- Wathsala S Nanayakkara
- Department of Human Nutrition, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
| | - Richard B Gearry
- Department of Medicine, University of Otago, P.O. Box 4345, Christchurch 8140, New Zealand.
| | - Jane G Muir
- Department of Gastroenterology, Monash University, 99 Commercial Rd, Melbourne VIC 3004, Australia.
| | - Leigh O'Brien
- Department of Human Nutrition, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
| | - Tim J Wilkinson
- Department of Medicine, University of Otago, P.O. Box 4345, Christchurch 8140, New Zealand.
| | - Jonathan A Williman
- Department of Population Health, University of Otago, P.O. Box 4345, Christchurch 8140, New Zealand.
| | - Paula M L Skidmore
- Department of Human Nutrition, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
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Shim YK, Kim N, Park YH, Lee JC, Sung J, Choi YJ, Yoon H, Shin CM, Park YS, Lee DH. Effects of Age on Esophageal Motility: Use of High-resolution Esophageal Impedance Manometry. J Neurogastroenterol Motil 2017; 23:229-236. [PMID: 28163259 PMCID: PMC5383117 DOI: 10.5056/jnm16104] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 12/19/2016] [Accepted: 01/15/2017] [Indexed: 01/10/2023] Open
Abstract
Background/Aims Disturbances of esophageal motility have been reported to be more frequent the aged population. However, the physiology of disturbances in esophageal motility during aging is unclear. The aim of this study was to evaluate the effects of age on esophageal motility using high-resolution esophageal impedance manometry (HRIM). Methods Esophageal motor function of 268 subjects were measured using HRIM in 3 age groups, < 40 years (Group A, n = 32), 40–65 years (Group B, n = 185), and > 65 years (Group C, n = 62). Lower esophageal sphincter (LES) and upper esophageal sphincter (UES) pressures, integrated relaxation pressure, distal contractile integral, contractile front velocity, distal latency, and pressures and duration of contraction on 4 positions along the esophagus, and complete bolus transit were measured. Results Basal UES pressure was lower in Group C (P < 0.001) but there was no significant difference in the LES pressure among groups. Contractile duration on position 3 (10 cm from proximal LES high pressure zone) was longer in Group C (P = 0.001), and the contractile amplitude on position 4 (5 cm from proximal LES high pressure zone) was lower in Group C (P = 0.005). Distal contractile integral was lower in Group C (P = 0.037). Contractile front velocity (P = 0.015) and the onset velocity (P = 0.040) was lower in Group C. There was no significant difference in impedance values. Conclusions The decrease of UES pressure, distal esophageal motility, and peristaltic velocity might be related with esophageal symptoms in the aged population.
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Affiliation(s)
- Young Kwang Shim
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea
| | - Nayoung Kim
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.,Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine and Liver Research Institute, Seoul, Korea
| | - Yo Han Park
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea
| | - Jong-Chan Lee
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea
| | - Jihee Sung
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea
| | - Yoon Jin Choi
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea
| | - Hyuk Yoon
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea
| | - Cheol Min Shin
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea
| | - Young Soo Park
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea
| | - Dong Ho Lee
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.,Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine and Liver Research Institute, Seoul, Korea
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Vazquez Roque M, Bouras EP. Epidemiology and management of chronic constipation in elderly patients. Clin Interv Aging 2015; 10:919-30. [PMID: 26082622 PMCID: PMC4459612 DOI: 10.2147/cia.s54304] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Constipation is a common functional gastrointestinal disorder, with prevalence in the general population of approximately 20%. In the elderly population the incidence of constipation is higher compared to the younger population, with elderly females suffering more often from severe constipation. Treatment options for chronic constipation (CC) include stool softeners, fiber supplements, osmotic and stimulant laxatives, and the secretagogues lubiprostone and linaclotide. Understanding the underlying etiology of CC is necessary to determine the most appropriate therapeutic option. Therefore, it is important to distinguish from pelvic floor dysfunction (PFD), slow and normal transit constipation. Evaluation of a patient with CC includes basic blood work, rectal examination, and appropriate testing to evaluate for PFD and slow transit constipation when indicated. Pelvic floor rehabilitation or biofeedback is the treatment of choice for PFD, and its efficacy has been proven in clinical trials. Surgery is rarely indicated in CC and can only be considered in cases of slow transit constipation when PFD has been properly excluded. Other treatment options such as sacral nerve stimulation seem to be helpful in patients with urinary dysfunction. Botulinum toxin injection for PFD cannot be recommended at this time with the available evidence. CC in the elderly is common, and it has a significant impact on quality of life and the use of health care resources. In the elderly, it is imperative to identify the etiology of CC, and treatment should be based on the patient’s overall clinical status and capabilities.
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Affiliation(s)
- Maria Vazquez Roque
- Gastroenterology and Hepatology Department, Mayo Clinic, Jacksonville, FL, USA
| | - Ernest P Bouras
- Gastroenterology and Hepatology Department, Mayo Clinic, Jacksonville, FL, USA
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11
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Management of the Gastrointestinal Tract and Nutrition in the Geriatric Surgical Patient. Surg Clin North Am 2015; 95:85-101. [DOI: 10.1016/j.suc.2014.09.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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12
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Abstract
Anorectal medical disorders facing the elderly include fecal incontinence, fecal impaction with overflow fecal incontinence, chronic constipation, dyssynergic defecation, hemorrhoids, anal fissure, and pelvic floor disorders. This article discusses the latest advances in age-related changes in morphology and function of anal sphincter, changes in cellular and molecular biology, alterations in neurotransmitters and reflexes, and their impact on functional changes of the anorectum in the elderly. These biophysiologic changes have implications for the pathophysiology of anorectal disorders. A clear understanding and working knowledge of the functional anatomy and pathophysiology will enable appropriate diagnosis and treatment of these disorders.
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Affiliation(s)
- Siegfried W B Yu
- Division of Gastroenterology and Hepatology, Medical College of Georgia, Georgia Regents University, 1120 15th Street, Augusta, GA 30912, USA
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13
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de Sousa FC, de Miranda Neto MH. Morphometric and quantitative study of the myenteric neurons of the stomach of malnourished aging rats. Nutr Neurosci 2013; 12:167-74. [DOI: 10.1179/147683009x423337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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14
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Gamage PPKM, Ranson RN, Patel BA, Yeoman MS, Saffrey MJ. Myenteric neuron numbers are maintained in aging mouse distal colon. Neurogastroenterol Motil 2013; 25:e495-e505. [PMID: 23517051 DOI: 10.1111/nmo.12114] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 02/15/2013] [Indexed: 12/18/2022]
Abstract
BACKGROUND Age-associated myenteric neuronal loss has been described in several species. In some studies,cholinergic neurons have been reported to be selectively vulnerable, whereas nitrergic neurons are spared. Aging of the mouse enteric nervous system(ENS) and the subtypes of mouse myenteric neurons that may be lost have been little studied. We therefore investigated changes in the numbers of total neurons and two neuronal subpopulations in the mouse distal colon during aging. METHODS Wholemount preparations from 3–4-, 12–13-, 18–19-, and 24–25-month-old C57BL/6 mice were double immunolabeled with HuC/D antibody to identify the total neuronal population and antisera to either calbindin or neuronal nitric oxide synthase (nNOS) to identify myenteric neuronal subpopulations. Samples were analyzed by confocal microscopy. New procedures were employed to ensure unbiased counting and to correct for changes in gut dimensions with age and stretch during sample preparation. The density of nerve fibers in the tertiary plexus was also studied. KEY RESULTS No significant change in numbers of total neurons or of either subpopulation with age was measured, but because of gut growth, the density of myenteric neurons decreased between 3–4 and 12–13 months. The density of nNOS-immunoreactive nerve fibers in the tertiary plexus increased significantly with age, up to 18–19 months. Numerous swollen processes of CB and nNOS-immunoreactive neurons were observed in 18–19- and 24–25-month-old animals. Conclusions &Inferences These results indicate that aging does not result in a loss of myenteric neurons in mouse distal colon at the ages studied, although neurodegenerative changes, which may impact on neuronal function, do occur.
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Affiliation(s)
- P. P. K. M. Gamage
- Department of Life, Health and Chemical Sciences; Biomedical Research Network; Open University; Walton Hall; Milton Keynes; MK7 6AA; UK
| | - R. N. Ranson
- Faculty of Health and Life Sciences; Northumbria University; Ellison Building; Newcastle upon Tyne; NE1 8ST; UK
| | - B. A. Patel
- School of Pharmacy and Biomolecular Sciences, Huxley Building; University of Brighton; Lewes Road; Brighton; BN2 4GJ; UK
| | - M. S. Yeoman
- School of Pharmacy and Biomolecular Sciences, Huxley Building; University of Brighton; Lewes Road; Brighton; BN2 4GJ; UK
| | - M. J. Saffrey
- Department of Life, Health and Chemical Sciences; Biomedical Research Network; Open University; Walton Hall; Milton Keynes; MK7 6AA; UK
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15
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Urogenital consequences in ageing women. Best Pract Res Clin Obstet Gynaecol 2013; 27:699-714. [PMID: 23764480 DOI: 10.1016/j.bpobgyn.2013.03.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Revised: 02/20/2013] [Accepted: 03/22/2013] [Indexed: 12/18/2022]
Abstract
Various anatomical, physiological, genetic, lifestyle and reproductive factors interact throughout a woman's life span and contribute to pelvic floor disorders. Ageing affects pelvic floor anatomy and function, which can result in a variety of disorders, such as pelvic organ prolapse, lower urinary tract symptoms, dysfunctional bowel and bladder evacuation, and sexual dysfunction. The exact mechanisms and pathophysiological processes by which ageing affects pelvic floor and lower urinary and gastrointestinal tract anatomy and function are not always clear. In most cases, it is difficult to ascertain the exact role of ageing per se as an aetiological, predisposing or contributing factor. Other conditions associated with ageing that may co-exist, such as changes in mental status, can result in different types of pelvic floor dysfunction (e.g. functional incontinence). Pelvic organ dysfunction may be associated with significant morbidity and affect quality of life. These groups of patients often pose difficult diagnostic and therapeutic dilemmas owing to complex medical conditions and concurrent morbidities. In this chapter, we summarise the current evidence on the management of pelvic floor disorders, with emphasis on elderly women and the associations between the ageing process and these disorders. Clinicians with an understanding of the affect of ageing on the pelvic floor and lower urinary and gastrointestinal tract anatomy and function, and the complex interplay of other comorbidities, will be able to investigate, diagnose and treat appropriately there women. A holistic approach may result in substantial improvements in their quality of life.
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16
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Diss LB, Robinson SD, Wu Y, Fidalgo S, Yeoman MS, Patel BA. Age-related changes in melatonin release in the murine distal colon. ACS Chem Neurosci 2013; 4:879-87. [PMID: 23631514 DOI: 10.1021/cn4000617] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Constipation and fecal impaction are conditions of the bowel whose prevalence increases with age. Limited information is known about how these conditions manifest; however, functional deficits are likely to be due to changes in signaling within the bowel. This study investigated the effects of age on colonic mucosal melatonin (MEL) release and the consequences this had on colonic motility. Electrochemical measurements of MEL overflow demonstrated that both basal and mechanically stimulated MEL release decreased with age. The MEL/serotonin also decreased with increasing age, and the trend was similar to that of MEL overflow, suggestive that age-related changes were primarily due to a reduction in MEL levels. Levels of N-acetylserotonin and the N-acetylserotonin/serotonin ratio were reduced with age, providing an explanation for the reduction in MEL release. Decreases in colonic motility were observed in animals between 3 and 24 months old. Exogenous application of MEL could reverse this deficit in aged colon. In summary, we propose that the age-related decline in MEL release may be due to either decreases or alterations in mechanosensory channels and/or a loss in levels/activity of the N-acetyltransferase enzyme responsible for the synthesis of N-acetylserotonin. Decreases in MEL release may explain the decreases in colonic motility observed in 24 month old animals and could offer a new potential therapeutic treatment for age-related constipation.
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Affiliation(s)
- Lucy B. Diss
- School of Pharmacy and
Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Stephen D. Robinson
- School of Pharmacy and
Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Yukyee Wu
- School of Pharmacy and
Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Sara Fidalgo
- School of Pharmacy and
Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Mark S. Yeoman
- School of Pharmacy and
Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Bhavik Anil Patel
- School of Pharmacy and
Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
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17
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Saffrey MJ. Cellular changes in the enteric nervous system during ageing. Dev Biol 2013; 382:344-55. [PMID: 23537898 DOI: 10.1016/j.ydbio.2013.03.015] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 02/22/2013] [Accepted: 03/19/2013] [Indexed: 02/06/2023]
Abstract
The intrinsic neurons of the gut, enteric neurons, have an essential role in gastrointestinal functions. The enteric nervous system is plastic and continues to undergo changes throughout life, as the gut grows and responds to dietary and other environmental changes. Detailed analysis of changes in the ENS during ageing suggests that enteric neurons are more vulnerable to age-related degeneration and cell death than neurons in other parts of the nervous system, although there is considerable variation in the extent and time course of age-related enteric neuronal loss reported in different studies. Specific neuronal subpopulations, particularly cholinergic myenteric neurons, may be more vulnerable than others to age-associated loss or damage. Enteric degeneration and other age-related neuronal changes may contribute to gastrointestinal dysfunction that is common in the elderly population. Evidence suggests that caloric restriction protects against age-associated loss of enteric neurons, but recent advances in the understanding of the effects of the microbiota and the complex interactions between enteric ganglion cells, mucosal immune system and intestinal epithelium indicate that other factors may well influence ageing of enteric neurons. Much remains to be understood about the mechanisms of neuronal loss and damage in the gut, although there is evidence that reactive oxygen species, neurotrophic factor dysregulation and/or activation of a senescence associated phenotype may be involved. To date, there is no evidence for ongoing neurogenesis that might replace dying neurons in the ageing gut, although small local sites of neurogenesis would be difficult to detect. Finally, despite the considerable evidence for enteric neurodegeneration during ageing, and evidence for some physiological changes in animal models, the ageing gut appears to maintain its function remarkably well in animals that exhibit major neuronal loss, indicating that the ENS has considerable functional reserve.
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Affiliation(s)
- M Jill Saffrey
- Department Life, Health & Chemical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, United Kingdom.
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18
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Korsak K, Dolatshad NF, Silva AT, Saffrey MJ. Ageing of enteric neurons: oxidative stress, neurotrophic factors and antioxidant enzymes. Chem Cent J 2012; 6:80. [PMID: 22857398 PMCID: PMC3469348 DOI: 10.1186/1752-153x-6-80] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 07/10/2012] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Ageing is associated with gastrointestinal dysfunction, which can have a major impact on quality of life of the elderly. A number of changes in the innervation of the gut during ageing have been reported, including neuronal loss and degenerative changes. Evidence indicates that reactive oxygen species (ROS) are elevated in ageing enteric neurons, but that neurotrophic factors may reduce generation of neuronal ROS. Two such factors, glial cell line derived neurotrophic factor (GDNF) and neurotrophin-3 (NT-3) have also been found to protect enteric neurons against oxidative stress induced cell death of enteric ganglion cells in vitro. We have investigated the possible roles of neurotrophic factors further, by examining their expression in the gut during ageing, and by analysing their effects on antioxidant enzyme production in cultures of enteric ganglion cells. RESULTS Analysis of the expression of GDNF and its receptors c-Ret and GFR α - 1 in rat gut by RT-PCR showed that expression continues throughout life and into ageing, in both ad libitum(AL) and calorically-restricted (CR) animals. Levels of expression of GDNF and GFR α - 1 were elevated in 24 month AL animals compared to 24 month CR animals, and to 24 CR and 6 month control animals respectively. The related factor Neurturin and its receptor GFR α - 2 were also expressed throughout life, the levels of the GFR - α-2(b) isoform were reduced in 24 m AL animals. Immunolabelling showed that c-Ret and GFR α - 1 proteins were expressed by myenteric neurons in ageing animals. GDNF, but not NT-3, was found to increase expression of Cu/Zn superoxide dismutase and catalase by cultured enteric ganglion cells. CONCLUSIONS The neurotrophic factors GDNF and neurturin and their receptors continue to be expressed in the ageing gut. Changes in the levels of expression of GDNF , GFR α-1 and GFR α-2(b) isoform occurred in 24 m AL animals. GDNF, but not NT-3, increased the levels of antioxidant enzymes in cultured enteric ganglion cells, indicating a possible mechanism for the reported protective effect of GDNF against menadione-induced neuronal apoptosis in the ageing gut. Together these data suggest that GDNF family members may play a protective role in the gut throughout life, and support the suggestion that dysregulation of neurotrophic factor support could contribute to neuronal ageing in the gut.
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Affiliation(s)
- Kris Korsak
- Department of Life, Health and Chemical Sciences, Biomedical Research Network, The Open University, Milton Keynes MK7 6AA, UK.
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Hoyle CHV, Saffrey MJ. Effects of aging on cholinergic neuromuscular transmission in isolated small intestine of ad libitum fed and calorically-restricted rats. Neurogastroenterol Motil 2012; 24:586-92. [PMID: 22435850 DOI: 10.1111/j.1365-2982.2012.01913.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Age-associated losses of enteric neurons have been described. In rat ileum, myenteric neurons lost during aging have been reported to be predominantly cholinergic, and caloric restriction (CR) has been shown to protect against these losses. Cholinergic myenteric neurons include excitatory motor neurons, so the aim of this work was to determine whether neuronal loss in ad libitum (AL)-fed animals is reflected in dysfunctional cholinergic neuromuscular transmission, and if CR reduces any such dysfunction. METHODS Effects of electrical field stimulation (EFS) and applied acetylcholine (ACh) were examined in the longitudinal muscle of isolated ileal segments from 6-month-old rats and from 13- and 24-month-old rats fed either AL or CR diets. KEY RESULTS Contractile responses to EFS were abolished by atropine and potentiated by the acetylcholinesterase inhibitor, eserine. Frequency-response relationships were not significantly different amongst the three age-groups. Sensitivity to applied ACh, however, was three-fold lower in the oldest animals (P < 0.05). Eserine potentiated responses to ACh; there were no statistically significant differences amongst the sensitivities to ACh in its presence. No significant differences between AL- and CR-fed animals were measured, although variability was less in CR-fed than in AL-fed groups. CONCLUSIONS & INFERENCES The cholinergic system supplying the rat ileum longitudinal muscle did not appear to be impaired in old age. Decreased sensitivity to applied ACh in old tissues may have been due to increased acetylcholinesterase activity. Caloric restriction had no significant effect on responses to EFS or applied ACh. The implications of these results are discussed.
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Affiliation(s)
- C H V Hoyle
- Department of Anatomy and Developmental Biology, University College London, London, UK
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20
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Korsak K, Silva AT, Saffrey MJ. Differing effects of NT-3 and GDNF on dissociated enteric ganglion cells exposed to hydrogen peroxide in vitro. Neurosci Lett 2012; 517:102-6. [PMID: 22548772 DOI: 10.1016/j.neulet.2012.04.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 03/26/2012] [Accepted: 04/13/2012] [Indexed: 01/19/2023]
Abstract
Oxidative stress is widely recognized to contribute to neuronal death during various pathological conditions and ageing. In the enteric nervous system (ENS), reactive oxygen species have been implicated in the mechanism of age-associated neuronal loss. The neurotrophic factors, neurotrophin 3 (NT-3) and glial cell line-derived neurotrophic factor (GDNF), are important in the development of enteric neurons and continue to be expressed in the gut throughout life. It has therefore been suggested that they may have a neuroprotective role in the ENS. We investigated the potential of NT-3 and GDNF to prevent the death of enteric ganglion cells in dissociated cell culture after exposure to hydrogen peroxide (H(2)O(2)). H(2)O(2) treatment resulted in a dose-dependent death of enteric neurons and glial cells, as demonstrated by MTS assay, bis-benzimide and propidium iodide staining and immunolabelling. Cultures treated with NT-3 prior to exposure showed reduced cell death compared to untreated control or GDNF-treated cultures. GDNF treatment did not affect neuronal survival in H(2)O(2)-treated cultures. These results suggest that NT-3 is able to enhance the survival of enteric ganglion cells exposed to oxidative stress.
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Affiliation(s)
- Kris Korsak
- Department of Life, Health and Chemical Sciences, The Open University, UK
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Parmar L, Fidalgo S, Yeoman MS, Patel BA. Chromatographic analysis of age-related changes in mucosal serotonin transmission in the murine distal ileum. Chem Cent J 2012; 6:31. [PMID: 22494644 PMCID: PMC3483693 DOI: 10.1186/1752-153x-6-31] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 02/27/2012] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND In the upper bowel, alterations in motility and absorption of key nutrients have been observed as part of the normal ageing process. Serotonin (5-HT) is a key signalling molecule in the gastrointestinal tract and is known to influence motility, however little is known of how the ageing process alters 5-HT signalling processes in the bowel. RESULTS An isocratic chromatographic method was able to detect all 5-HT precursors and metabolites. Using extracellular and intracellular sampling approaches, we were able to monitor all key parameters associated with the transmission process. There was no alteration in the levels of tryptophan and 5-HTP between 3 and 18 month old animals. There was a significant increase in the ratio of 5-HT:5-HTP and an increase in intracellular 5-HT between 3 and 18 month old animals suggesting an increase in 5-HT synthesis. There was also a significant increase in extracellular 5-HT with age, suggesting increased 5-HT release. There was an age-related decrease in the ratio of intracellular 5-HIAA:extracellular 5-HT, whilst the amount of 5-HIAA did not change with age. In the presence of an increase in extracellular 5-HT, the lack of an age-related change in 5-HIAA is suggestive of a decrease in re-uptake via the serotonin transporter (SERT). CONCLUSIONS We have used intracellular and extracellular sampling to provide more insight into alterations in the neurotransmission process of 5-HT during normal ageing. We observed elevated 5-HT synthesis and release and a possible decrease in the activity of SERT. Taken together these changes lead to increased 5-HT availability and may alter motility function and could lead to the changes in adsorption observed in the elderly.
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Affiliation(s)
- Leena Parmar
- Centre for Biomedical and Health Sciences Research, University of Brighton, Brighton, BN2 4GJ, UK.
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22
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Park KS. [Aging and digestive diseases: at the view of the functional change of gastrointestinal tract]. THE KOREAN JOURNAL OF GASTROENTEROLOGY 2011; 58:3-8. [PMID: 21778797 DOI: 10.4166/kjg.2011.58.1.3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Although it is difficult to define the term "aging" consensually, in medical fields, usually it means the progressive accumulation of irreversible degenerative changes leading to loss of homeostasis. It is supposable that there is also modest decline in the structure and function of several digestive organs. However, data about this subject are not enough. Main problem in studying aging digestive organ is that discrimination of primary senile change of the organ with secondary one from other senile diseases is not easy. That is, the prevalence of many non-digestive disorders which can badly affect the digestive functions is increasing by aging; for example, diabetes, malignancy, etc. To prove that some phenomenon is as result of pure senile change, it is necessary to exclude secondary one, but, the process is very complicated and difficult. In spite of this limitation, here, I will discuss the senile change of several digestive organs by aging, especially at the view of the gastrointestinal functions, with review of literatures.
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Affiliation(s)
- Kyung Sik Park
- Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea.
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Asuzu DT, Hayashi Y, Izbeki F, Popko LN, Young DL, Bardsley MR, Lorincz A, Kuro-o M, Linden DR, Farrugia G, Ordog T. Generalized neuromuscular hypoplasia, reduced smooth muscle myosin and altered gut motility in the klotho model of premature aging. Neurogastroenterol Motil 2011; 23:e309-23. [PMID: 21605285 PMCID: PMC3149585 DOI: 10.1111/j.1365-2982.2011.01730.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Gastrointestinal symptoms, particularly constipation, increase with aging, but their underlying mechanisms are poorly understood due to lack of experimental models. Previously we established the progeric klotho mouse as a model of aging-associated anorexia and gastric dysmotility. We also detected reduced fecal output in these animals; therefore, the aim of this study was to investigate in vivo function and cellular make-up of the small intestinal and colonic neuromuscular apparatus. METHODS Klotho expression was studied by RT-PCR and immunohistochemistry. Motility was assessed by dye transit and bead expulsion. Smooth muscle and neuron-specific gene expression was studied by Western immunoblotting. Interstitial cells of Cajal (ICC) and precursors were analyzed by flow cytometry, confocal microscopy, and three-dimensional reconstruction. HuC/D(+) myenteric neurons were enumerated by fluorescent microscopy. KEY RESULTS Klotho protein was detected in neurons, smooth muscle cells, and some ICC classes. Small intestinal transit was slower but whole-gut transit of klotho mice was accelerated due to faster colonic transit and shorter intestinal lengths, apparent only after weaning. Fecal water content remained normal despite reduced output. Smooth muscle myosin expression was reduced. ICC, ICC precursors, as well as nitrergic and cholinergic neurons maintained their normal proportions in the shorter intestines. CONCLUSIONS & INFERENCES Progeric klotho mice express less contractile proteins and develop generalized intestinal neuromuscular hypoplasia mainly arising from stunted postweaning growth. As reduced fecal output in these mice occurs in the presence of accelerated colonic and whole-gut transit, it likely reflects reduced food intake rather than intestinal dysmotility.
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Affiliation(s)
- David T. Asuzu
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA,Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Yujiro Hayashi
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA,Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Ferenc Izbeki
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA,Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Laura N. Popko
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA,Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - David L. Young
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA,Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Michael R. Bardsley
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA,Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrea Lorincz
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA,Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Makoto Kuro-o
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - David R. Linden
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Gianrico Farrugia
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Tamas Ordog
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA,Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905, USA
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Gender- and age-related differences in muscular and nerve-mediated responses in human colon. Dig Dis Sci 2011; 56:352-8. [PMID: 20658192 DOI: 10.1007/s10620-010-1324-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 06/17/2010] [Indexed: 01/12/2023]
Abstract
BACKGROUND Gender- and age-related differences in muscular and nerve-mediated responses in human colon are poorly characterized. We studied carbachol-induced motor responses and electrically evoked contractions in sigmoid circular muscle from adult and elderly patients of different gender. METHODS Sigmoid colon segments were obtained from 24 men and 16 women undergoing left hemicolectomy for colon cancer. Isometric tension was measured on muscle strips exposed to increasing carbachol concentrations. The effects of atropine, guanethidine, L-nitro arginine methyl ester (L-NAME), and tetrodotoxin on electrically evoked contractions were also studied. RESULTS Female patients showed higher maximal response to carbachol than male patients, elderly females being the most sensitive to carbachol among all patient groups. Electrically evoked contractions were linearly related to stimulation frequency and abolished by tetrodotoxin. Electrically evoked contractions were significantly more pronounced in elderly male patients; they were reduced by atropine and guanethidine and increased by L-nitro arginine methyl ester in the presence of atropine and guanethidine (P < 0.05). The effect of L-NAME was most marked in elderly male patients and least pronounced in elderly females. CONCLUSIONS The response to carbachol and the role of nitrergic pathways differ according to age and gender; this may depend on muscarinic receptor upregulation or humoral factors affecting nitric oxide release, respectively.
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Enteric nervous system in the small intestine: pathophysiology and clinical implications. Curr Gastroenterol Rep 2011; 12:358-65. [PMID: 20725870 DOI: 10.1007/s11894-010-0129-9] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The digestive system is endowed with its own, local nervous system, referred to as the enteric nervous system (ENS). Given the varied functions of small intestine, its ENS has developed individualized characteristics relating to motility, secretion, digestion, and inflammation. The ENS regulates the major enteric processes such as immune response, detecting nutrients, motility, microvascular circulation, intestinal barrier function, and epithelial secretion of fluids, ions, and bioactive peptides. Remarkable progress has been made in understanding the signaling pathways in this complex system and how they work. In this article, we focus on recent advances that have led to new insights into small intestinal ENS function and the development of new therapies.
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Bassotti G, Villanacci V. Can "functional" constipation be considered as a form of enteric neuro-gliopathy? Glia 2010; 59:345-50. [PMID: 21264943 DOI: 10.1002/glia.21115] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 11/03/2010] [Indexed: 12/12/2022]
Abstract
Constipation has been traditionally viewed and classified as a functional or idiopathic disorder. However, evidence has been accumulating that suggests how constipation might be considered as due to abnormalities of the enteric nervous system, since alterations of this system, not evident in conventional histological examination, may be present in these patients. These abnormalities often consist in decrease or loss of the enteric glial cells, a pathological finding present in most types of constipation so far investigated. In this article we will discuss these evidences, and will try to consider constipation no more as a simple functional or idiopathic disorder but as a form of enteric neuro-gliopathy.
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Affiliation(s)
- Gabrio Bassotti
- Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology Section, University of Perugia, Italy.
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Ahmed T, Haboubi N. Assessment and management of nutrition in older people and its importance to health. Clin Interv Aging 2010; 5:207-16. [PMID: 20711440 PMCID: PMC2920201 DOI: 10.2147/cia.s9664] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Indexed: 12/21/2022] Open
Abstract
Nutrition is an important element of health in the older population and affects the aging process. The prevalence of malnutrition is increasing in this population and is associated with a decline in: functional status, impaired muscle function, decreased bone mass, immune dysfunction, anemia, reduced cognitive function, poor wound healing, delayed recovery from surgery, higher hospital readmission rates, and mortality. Older people often have reduced appetite and energy expenditure, which, coupled with a decline in biological and physiological functions such as reduced lean body mass, changes in cytokine and hormonal level, and changes in fluid electrolyte regulation, delay gastric emptying and diminish senses of smell and taste. In addition pathologic changes of aging such as chronic diseases and psychological illness all play a role in the complex etiology of malnutrition in older people. Nutritional assessment is important to identify and treat patients at risk, the Malnutrition Universal Screening Tool being commonly used in clinical practice. Management requires a holistic approach, and underlying causes such as chronic illness, depression, medication and social isolation must be treated. Patients with physical or cognitive impairment require special care and attention. Oral supplements or enteral feeding should be considered in patients at high risk or in patients unable to meet daily requirements.
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Affiliation(s)
- Tanvir Ahmed
- Adult and Elderly Medicine, Nevill Hall Hospital, Abergavenny, Wales, UK
| | - Nadim Haboubi
- Adult and Elderly Medicine, Nevill Hall Hospital, Abergavenny, Wales, UK
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Triantafyllou K, Vlachogiannakos J, Ladas SD. Gastrointestinal and liver side effects of drugs in elderly patients. Best Pract Res Clin Gastroenterol 2010; 24:203-15. [PMID: 20227033 DOI: 10.1016/j.bpg.2010.02.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 02/07/2010] [Accepted: 02/08/2010] [Indexed: 01/31/2023]
Abstract
It is expected that the percentage of people >60 years of age will be 22% worldwide by the year 2050. Multi-morbidity and poly-pharmacy are common in individuals during old age, while adverse drug reactions are at least twice as common in the elderly compared to younger adults. Publications related to drug side effects are rather rare in this age group since most clinical trials exclude patients >75-80 years of age. Gastrointestinal adverse drug reactions studied in the elderly include non-steroidal anti-inflammatory drugs (NSAIDs) and anticoagulant-induced gastrointestinal tract mucosal injuries. Malabsorption, diarrhoea and constipation are common side effects of laxatives, antibiotics, anticholinergics and calcium channel blockers. Drug (amoxycilin/clavulanic acid, isoniazide, nitrofurantoin, diclifenac and methotrexate)-induced hepatotoxicity in the elderly is four times more common than in younger adults and may simulate almost all known liver disorders. Further clinical studies are needed to investigate gastrointestinal and hepatic side effects of drugs in elderly patients.
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Affiliation(s)
- Konstantinos Triantafyllou
- Hepatogastroenterology Unit, 2nd Department of Internal Medicine - Propaedeutic, Attikon University General Hospital, Medical School, Athens University, Chaidari, Greece
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29
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Schäfer KH, Van Ginneken C, Copray S. Plasticity and neural stem cells in the enteric nervous system. Anat Rec (Hoboken) 2010; 292:1940-52. [PMID: 19943347 DOI: 10.1002/ar.21033] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The enteric nervous system (ENS) is a highly organized part of the autonomic nervous system, which innervates the whole gastrointestinal tract by several interconnected neuronal networks. The ENS changes during development and keeps throughout its lifespan a significant capacity to adapt to microenvironmental influences, be it in inflammatory bowel diseases or changing dietary habits. The presence of neural stem cells in the pre-, postnatal, and adult gut might be one of the prerequisites to adapt to changing conditions. During the last decade, the ENS has increasingly come into the focus of clinical neural stem cell research, forming a considerable pool of neural crest derived stem cells, which could be used for cell therapy of dysganglionosis, that is, diseases based on the deficient or insufficient colonization of the gut by neural crest derived stem cells; in addition, the ENS could be an easily accessible neural stem cell source for cell replacement therapies for neurodegenerative disorders or traumatic lesions of the central nervous system.
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Affiliation(s)
- Karl-Herbert Schäfer
- Department of Biotechnology, University of Applied Sciences Kaiserslautern, Amerikastrasse 1, Zweibrücken, Germany.
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30
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Phillips RJ, Walter GC, Powley TL. Age-related changes in vagal afferents innervating the gastrointestinal tract. Auton Neurosci 2010; 153:90-8. [PMID: 19665435 PMCID: PMC2818053 DOI: 10.1016/j.autneu.2009.07.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2009] [Revised: 07/11/2009] [Accepted: 07/13/2009] [Indexed: 12/16/2022]
Abstract
Recent progress in understanding visceral afferents, some of it reviewed in the present issue, serves to underscore how little is known about the aging of the visceral afferents in the gastrointestinal (GI) tract. In spite of the clinical importance of the issue-with age, GI function often becomes severely compromised-only a few initial observations on age-related structural changes of visceral afferents are available. Primary afferent cell bodies in both the nodose ganglia and dorsal root ganglia lose Nissl material and accumulate lipofucsin, inclusions, aggregates, and tangles. Additionally, in changes that we focus on in the present review, vagal visceral afferent terminals in both the muscle wall and the mucosa of the GI tract exhibit age-related structural changes. In aged animals, both of the vagal terminal types examined, namely intraganglionic laminar endings and villus afferents, exhibit dystrophic or regressive morphological changes. These neuropathies are associated with age-related changes in the structural integrity of the target organs of the affected afferents, suggesting that local changes in trophic environment may give rise to the aging of GI innervation. Given the clinical relevance of GI tract aging, a more complete understanding both of how aging alters the innervation of the gut and of how such changes might be mitigated should be made research priorities.
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Affiliation(s)
- Robert J Phillips
- Purdue University, Ingestive Behavior Research Center, Department of Psychological Sciences, West Lafayette, IN 47907-2081, USA.
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31
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Carlsson M, Gustafson Y, Haglin L, Eriksson S. The feasibility of serving liquid yoghurt supplemented with probiotic bacteria, Lactobacillus rhamnosus LB 21, and Lactococcus lactis L1A--a pilot study among old people with dementia in a residential care facility. J Nutr Health Aging 2009; 13:813-9. [PMID: 19812872 DOI: 10.1007/s12603-009-0218-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Constipation and body weight loss are prevalent among old people. Treatment with different species of lactic acid bacteria has been suggested for various forms of gastrointestinal disorders. OBJECTIVE, PARTICIPANTS AND INTERVENTION: This pilot study was performed to assess the feasibility of administering and consuming a drinkable yoghurt containing Lactobacillus rhamnosus LB 21 and Lactococcus L1A, and to evaluate the influence on bowel movements and body weight in 15 people with dementia, aged 65-95 years in residential care facility. DESIGN A drinkable yoghurt (Verum Drickyoghurt) with added bacteria was served daily for 6 months in conjunction with ordinary food intake. Body weight, bowel movement frequency and consistency, food and fluid intake and time spent in various activities were recorded for two weeks pre-intervention, and 3 times during the follow-up period. RESULT This study showed that the yoghurt was easy to serve, with few side effects for the participants and that the various recording forms and diaries were easy for the staff to complete. The extra intake of yoghurt did not have any detectable beneficial effect on bowel movements. The overnight fast was almost 15 hours per day. Body weight decreased by 0.65 kg/month (95% confidence interval. 0.27-0.97). CONCLUSIONS The present study design was feasible in this group of old people with dementia. The absence of any detectable effect of the supplement on constipation, but rather a considerable loss in body weight, indicate that further research is needed in a large randomised controlled trial, if associations between dementia, constipation and energy balance are to be understood.
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Affiliation(s)
- M Carlsson
- Department of Community Medicine and Rehabilitation, Geriatric Medicine, Umeå University, SE-901 86 Umeå, Sweden.
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32
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Abstract
Chronic constipation is a common problem in the elderly, with a variety of causes, including pelvic floor dysfunction, medication effects, and numerous age-specific conditions. A stepwise diagnostic and therapeutic approach to patients with chronic constipation based on historical and physical examination features is recommended. Prudent use of fiber supplements and laxative agents may be helpful for many patients. Based on their capabilities, patients with pelvic floor dysfunction should be considered for pelvic floor rehabilitation (biofeedback), although efficacy in the elderly is uncertain. Clinical awareness and focused testing to identify the physiologic abnormalities underlying constipation, while being mindful of situations unique to the elderly, facilitate management, and improve patient outcomes.
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Affiliation(s)
- Ernest P Bouras
- Department of Medicine, Division of Gastroenterology and Hepatology, E6A, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
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Sprenger N, Julita M, Donnicola D, Jann A. Sialic acid feeding aged rats rejuvenates stimulated salivation and colon enteric neuron chemotypes. Glycobiology 2009; 19:1492-502. [PMID: 19696237 DOI: 10.1093/glycob/cwp124] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Old age is linked to numerous changes of body functions such as salivation, gastrointestinal motility, and permeability all linked to central and enteric nervous system decline. Thus, gut motility and barrier functions suffer. Sialic acid plays a key role in the nervous system at large and for many receptor functions specifically. Decreased sialylation in the elderly suggests an endogenous sialic acid deficit. We used a rat model of aging, to ask whether sialic acid feeding would affect (i) stimulated salivation, (ii) gut functions, and (iii) sialic acid levels and neuronal markers in brain and gut. We observed reduced levels of pilocarpine-stimulated salivation in old versus young rats and restored this function by sialic acid feeding. Brain ganglioside bound sialic acid levels were found lower in aged versus young rats, and sialic acid feeding partly restored the levels. The hypothalamic expression of cholinergic and panneuronal markers was reduced in aged rats. The expression of the nitrergic marker nNOS was increased upon sialic acid feeding in aged rats. Neither fecal output nor gut permeability was different between young and aged rats studied here, and sialic acid feeding did not alter these parameters. However, the colonic expression of specific nervous system markers nNOS and Uchl1 and the key enzyme for sialic acid synthesis GNE were differentially affected in young and aged rats by sialic acid feeding indicating that regulatory mechanisms change with age. Investigation of sialic acid supplementation as a functional nutrient in the elderly may help those who suffer from disorders of reduced salivation. Further research is needed to understand the differential effects of sialic acid feeding in young and aged rats.
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Affiliation(s)
- Norbert Sprenger
- Nestlé Research Center, Vers-chez-les-Blanc, Lausanne 26, CH-1000 Switzerland.
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34
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Phillips RJ, Walter GC, Ringer BE, Higgs KM, Powley TL. Alpha-synuclein immunopositive aggregates in the myenteric plexus of the aging Fischer 344 rat. Exp Neurol 2009; 220:109-19. [PMID: 19664623 DOI: 10.1016/j.expneurol.2009.07.025] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 07/12/2009] [Accepted: 07/26/2009] [Indexed: 12/12/2022]
Abstract
Dystrophic axons and terminals are common in the myenteric plexus and smooth muscle of the gastrointestinal (GI) tract of aged rats. In young adult rats, alpha-synuclein in its normal state is abundant throughout the myenteric plexus, making this protein-which is prone to fibrillization-a candidate marker for axonopathies in the aged rat. To determine if aggregation of alpha-synuclein is involved in the formation of age-related enteric neuropathies, we sampled the stomach, small intestine and large intestine of adult, middle-aged, and aged virgin male Fischer 344 rats stained for alpha-synuclein in both its normal and pathological states. Alpha-synuclein-positive dystrophic axons and terminals were present throughout the GI tract of middle-aged and aged rats, with immunohistochemical double labeling demonstrating co-localization within nitric oxide synthase-, calretinin-, calbindin-, or tyrosine hydroxylase-positive markedly swollen neurites. However, other dystrophic neurites positive for each of these four markers were not co-reactive for alpha-synuclein. Similarly, a subpopulation of alpha-synuclein inclusions contained deposits immunostained with an anti-tau phospho-specific Ser(262) antibody, but not all of these hyperphosphorylated tau-positive aggregates were co-localized with alpha-synuclein. The presence of heteroplastic and potentially degenerating neural elements and protein aggregates both positive and negative for alpha-synuclein suggests a complex chronological relationship between the onset of degenerative changes and the accumulation of misfolded proteins. Additionally, proteins other than alpha-synuclein appear to be involved in age-related axonopathies. Finally, this study establishes the utility of the aging Fischer 344 rat for the study of synucleopathies and tauopathies in the GI tract.
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Affiliation(s)
- Robert J Phillips
- Purdue University, Department of Psychological Sciences, 703 Third Street, West Lafayette, IN 47907-2081, USA.
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35
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Choi JH, Lee CH, Chung DW, Hwang IK, Won MH, Seong JK, Yoon YS, Lee IS. Age-related changes of calbindin D-28k-immunoreactive neurons in the myenteric plexus of gerbil duodenum. J Vet Med Sci 2008; 70:343-8. [PMID: 18460827 DOI: 10.1292/jvms.70.343] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined the age-related changes of calbindin D-28k (CB)-immunoreactive neurons and overall populations of neurons in the myenteric plexus of gerbil duodenum using whole mount preparations and immunohistochemistry. The circumference of duodenum increased age-dependently. CB-immunoreactive neurons were observed in all groups, and most of them had the Dogiel type II morphology. The fully developed cobweb-like structures were observed in the myenteric plexus of duodenum at postnatal month (PM) 3 to 24. Although the highest numbers of CB-immunoreactive neurons and overall population were observed in PM 1.5, it is related with significant increase of the size of circumference between PM 1.5 to PM 3. CB-immunoreactive neurons were slightly decreased with age between PM 3 to PM 24. We have also found that whole numbers of myenteric neurons were also significantly decreased in PM 24 group. These results suggest that loss of overall numbers of myenteric neurons and CB-immunoreactive neurons may be related with age-related neurodegeneration and functional loss of duodenum in the gerbil.
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Affiliation(s)
- Jung Hoon Choi
- Department of Anatomy and Cell Biology, College of Veterinary Medicine and BK21 Program for Veterinary Science, Seoul National University, Seoul, South Korea
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36
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Cersosimo MG, Benarroch EE. Neural control of the gastrointestinal tract: implications for Parkinson disease. Mov Disord 2008; 23:1065-75. [PMID: 18442139 DOI: 10.1002/mds.22051] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Disorders of swallowing and gastrointestinal motility are prominent nonmotor manifestations of Parkinson disease (PD). Motility of the gut is controlled both by extrinsic inputs from the dorsal motor nucleus of the vagus (DMV) and paravertebral sympathetic ganglia and by local reflexes mediated by intrinsic neurons of the enteric nervous system (ENS). Both the ENS and the DMV are affected by Lewy body pathology at early stages of PD. This early involvement provides insights into the pathophysiology of gastrointestinal dysmotility in this disorder and may constitute an important step in the etiopathogenesis of Lewy body disease.
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Affiliation(s)
- Maria G Cersosimo
- Parkinson's Disease and Movement Disorder Unit, Hospital de Clínicas, University of Buenos Aires, Argentina
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37
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Hoff S, Zeller F, von Weyhern CWH, Wegner M, Schemann M, Michel K, Rühl A. Quantitative assessment of glial cells in the human and guinea pig enteric nervous system with an anti-Sox8/9/10 antibody. J Comp Neurol 2008; 509:356-71. [PMID: 18512230 DOI: 10.1002/cne.21769] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Quantitative changes of enteric glia (EGC) have been implicated in gastrointestinal disorders. To facilitate future studies of EGC in human pathology, we aimed to characterize thoroughly glial markers in the human enteric nervous system (ENS) and to compare EGC in man and guinea pig. Whole-mount preparations of the enteric nerve plexuses from human and guinea pig ileum and colon were labeled with antibodies against S100b, glial fibrillary acidic protein (GFAP), and p75NGFR and the transcription factors Sox8/9/10 and neuronally counterstained. Abundant immunoreactivity (IR) for S100b, GFAP, p75NGFR, and Sox8/9/10 was detected in EGC of all studied regions. Although the cytoplasmatic staining pattern of most markers did not permit glial quantification, the nuclear localization of Sox8/9/10-IR allowed to identify and count all EGC individually. In both man and guinea pig, myenteric ganglia were larger and contained more EGC and neurons than submucous ganglia. Furthermore, there were more EGC in the human than in the guinea pig myenteric plexus (MP), glial density was consistently higher in the human ENS, and the glia index (glia:neuron ratio) ranged from 1.3 to 1.9 and from 5.9 to 7.0 in the human submucous plexus (SMP) and MP, respectively, whereas, in guinea pig, the glia index was 0.8-1.0 in the SMP and 1.7 in the MP. The glia index was the most robust quantitative descriptor within one species. This is a comprehensive set of quantitative EGC measures in man and guinea pig that provides a basis for pathological assessment of glial proliferation and/or degeneration in the diseased gut.
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Affiliation(s)
- Sebastian Hoff
- Department of Human Biology, Technische Universität München, D-85350 Freising-Weihenstephan, Germany
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38
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Abstract
PURPOSE OF REVIEW With the graying of the world's population, there is an increased interest in the physiological effects of aging. This review examines the physiological changes of the gut with aging and their clinical significance. RECENT FINDINGS Changes with aging in the gastrointestinal tract are variable, but in some cases they are responsible for a variety of symptoms. Thus, alterations in taste and smell, gastric motility, intestinal overgrowth and changes in gastrointestinal hormone release are the basis of the physiological anorexia of aging. Alterations in swallowing lead to silent aspiration. Changes in gastric emptying play a role in postprandial hypotension. Changes in gastrointestinal function can lead to constipation and fecal incontinence. Weakening of the colonic muscular wall produces diverticula. Achlorhydria is associated with malabsorption of some forms of iron and calcium. Vitamin D malabsorption aggravates the hypovitaminosis D that is so common in older persons. Changes in probiotics can lead to diarrhea and altered immune system. In the liver, aging is associated with delayed drug metabolism. SUMMARY Changes in the physiology of the gut play a role in the anorexia of aging, aspiration pneumonia, postprandial hypotension, constipation and fecal incontinence.
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Affiliation(s)
- Asif Bhutto
- Division of Geriatric Medicine, Saint Louis University, USA bGRECC, VA Medical Center, St. Louis, Missouri, USA
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39
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De Britto Mari R, Clebis NK, Gagliardo KM, Guimares JP, Stabille SR, De Mello Germano R, De Souza RR. Effects of Exercise on the Morphology of the Myenteric Neurons of the Duodenum of Wistar Rats during the Ageing Process. Anat Histol Embryol 2008; 37:289-95. [DOI: 10.1111/j.1439-0264.2008.00843.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Abstract
Gastric emptying is mildly slowed in healthy aging, although generally remains within the normal range for young people. The significance of this is unclear, but may potentially influence the absorption of certain drugs, especially when a rapid effect is desired. Type 2 diabetes is common in the elderly, but there is little data regarding its natural history, prognosis, and management. This article focuses on the interactions between gastric emptying and diabetes, how each is influenced by the process of aging, and the implications for patient management.
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Affiliation(s)
- Paul Kuo
- Discipline of Medicine, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia 5000, Australia
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41
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Bassotti G, Villanacci V, Fisogni S, Rossi E, Baronio P, Clerici C, Maurer CA, Cathomas G, Antonelli E. Enteric glial cells and their role in gastrointestinal motor abnormalities: Introducing the neuro-gliopathies. World J Gastroenterol 2007; 13:4035-41. [PMID: 17696219 PMCID: PMC4205302 DOI: 10.3748/wjg.v13.i30.4035] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The role of enteric glial cells has somewhat changed from that of mere mechanical support elements, gluing together the various components of the enteric nervous system, to that of active participants in the complex interrelationships of the gut motor and inflammatory events. Due to their multiple functions, spanning from supporting elements in the myenteric plexuses to neurotransmitters, to neuronal homeostasis, to antigen presenting cells, this cell population has probably more intriguing abilities than previously thought. Recently, some evidence has been accumulating that shows how these cells may be involved in the pathophysiological aspects of some diseases. This review will deal with the properties of the enteric glial cells more strictly related to gastrointestinal motor function and the human pathological conditions in which these cells may play a role, suggesting the possibility of enteric neuro-gliopathies.
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42
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Abstract
The 5-HT(4) partial agonist tegaserod is effective in the treatment of chronic constipation and constipation predominant irritable bowel syndrome. 5-HT(4) receptors are located on presynaptic terminals in the enteric nervous system. Stimulation of 5-HT(4) receptors enhances the release of acetylcholine and calcitonin gene related peptide from stimulated nerve terminals. This action strengthens neurotransmission in prokinetic pathways, enhancing gastrointestinal motility. The knockout of 5-HT(4) receptors in mice not only slows gastrointestinal activity but also, after 1 month of age, increases the age-related loss of enteric neurons and decreases the size of neurons that survive. 5-HT(4) receptor agonists, tegaserod and RS67506, increase numbers of enteric neurons developing from precursor cells and/or surviving in culture; they also increase neurite outgrowth and decrease apoptosis. The 5-HT(4) receptor antagonist, GR113808, blocks all of these effects, which are thus specific and 5-HT(4)-mediated. 5-HT(4) receptor agonists, therefore, are neuroprotective and neurotrophic for enteric neurons. Because the age-related decline in numbers of enteric neurons may contribute to the dysmotilities of the elderly, the possibility that the neuroprotective actions of 5-HT agonists can be utilized to prevent the occurrence or worsening of these conditions should be investigated.
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Affiliation(s)
- M D Gershon
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA.
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43
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Abstract
The 5-HT(4) partial agonist tegaserod is effective in the treatment of chronic constipation and constipation predominant irritable bowel syndrome. 5-HT(4) receptors are located on presynaptic terminals in the enteric nervous system. Stimulation of 5-HT(4) receptors enhances the release of acetylcholine and calcitonin gene related peptide from stimulated nerve terminals. This action strengthens neurotransmission in prokinetic pathways, enhancing gastrointestinal motility. The knockout of 5-HT(4) receptors in mice not only slows gastrointestinal activity but also, after 1 month of age, increases the age-related loss of enteric neurons and decreases the size of neurons that survive. 5-HT(4) receptor agonists, tegaserod and RS67506, increase numbers of enteric neurons developing from precursor cells and/or surviving in culture; they also increase neurite outgrowth and decrease apoptosis. The 5-HT(4) receptor antagonist, GR113808, blocks all of these effects, which are thus specific and 5-HT(4)-mediated. 5-HT(4) receptor agonists, therefore, are neuroprotective and neurotrophic for enteric neurons. Because the age-related decline in numbers of enteric neurons may contribute to the dysmotilities of the elderly, the possibility that the neuroprotective actions of 5-HT agonists can be utilized to prevent the occurrence or worsening of these conditions should be investigated.
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Affiliation(s)
- M D Gershon
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA.
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44
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Bassotti G, Villanacci V, Antonelli E, Morelli A, Salerni B. Enteric glial cells: new players in gastrointestinal motility? J Transl Med 2007; 87:628-32. [PMID: 17483847 DOI: 10.1038/labinvest.3700564] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The enteric glial cells, in addition to being support structures for the enteric nervous system, have many other additional roles, such as modulators for the homeostasis of enteric neurons, cells involved in enteric neurotransmission and antigen-presenting cells. Moreover, in the last years, data have been accumulating that demonstrate a possible active role of these cells in the pathophysiology of gastrointestinal motor activity. Thus, as also shown by recent evidence in both experimental animal models, and in some human diseases, alterations of enteric glial cells might have some role in the development of intestinal motor abnormalities.
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Affiliation(s)
- Gabrio Bassotti
- Gastroenterology and Hepatology Section, Department of Clinical and Experimental Medicine, University of Perugia, Perugia, Italy.
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45
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Phillips RJ, Pairitz JC, Powley TL. Age-related neuronal loss in the submucosal plexus of the colon of Fischer 344 rats. Neurobiol Aging 2007; 28:1124-37. [DOI: 10.1016/j.neurobiolaging.2006.05.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 03/07/2006] [Accepted: 05/10/2006] [Indexed: 11/28/2022]
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46
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Phillips RJ, Powley TL. Innervation of the gastrointestinal tract: patterns of aging. Auton Neurosci 2007; 136:1-19. [PMID: 17537681 PMCID: PMC2045700 DOI: 10.1016/j.autneu.2007.04.005] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 04/10/2007] [Accepted: 04/24/2007] [Indexed: 12/12/2022]
Abstract
The gastrointestinal (GI) tract is innervated by intrinsic enteric neurons and by extrinsic projections, including sympathetic and parasympathetic efferents as well as visceral afferents, all of which are compromised by age to different degrees. In the present review, we summarize and illustrate key structural changes in the aging innervation of the gut, and suggest a provisional list of the general patterns of aging of the GI innervation. For example, age-related neuronal losses occur in both the myenteric plexus and submucosal plexus of the intestines. These losses start in adulthood, increase over the rest of the life span, and are specific to cholinergic neurons. Parallel losses of enteric glia also occur. The extent of neuronal and glial loss varies along an oral-to-anal gradient, with the more distal GI tract being more severely affected. Additionally, with aging, dystrophic axonal swellings and markedly dilated varicosities progressively accumulate in the sympathetic, vagal, dorsal root, and enteric nitrergic innervation of the gut. These dramatic and consistent patterns of neuropathy that characterize the aging autonomic nervous system of the GI tract are candidate mechanisms for some of the age-related declines in function evidenced in the elderly.
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Affiliation(s)
- Robert J Phillips
- Purdue University, Department of Psychological Sciences, 703 Third Street, West Lafayette, IN 47907-2081, USA.
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Bassotti G, Villanacci V, Fisogni S, Cadei M, Di Fabio F, Salerni B. Apoptotic phenomena are not a major cause of enteric neuronal loss in constipated patients with dementia. Neuropathology 2007; 27:67-72. [PMID: 17319285 DOI: 10.1111/j.1440-1789.2006.00740.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Chronic constipation is a frequent symptom in patients with dementia, especially in those institutionalized. However, few data are available on the neuropathological aspects of the colon in such patients. We investigated the enteric neuropathology of the colon in two patients with longstanding dementia and intractable constipation, requiring surgery to alleviate symptoms. The results were compared to those obtained in 10 controls. No abnormalities were found at conventional histological examination, except for the presence of melanosis coli. Immunohistochemical evaluation revealed no important difference between patients and controls, except for a decreased number of enteric neurons in patients. However, this neuronal decrease was not associated to apoptotic phenomena, as observed in patients with severe idiopathic constipation. We concluded that in severely constipated patients with dementia the neuropathological abnormalities might be reconducted to a physiological neuronal decrease as a result of aging, and that the pathophysiological aspects of constipation in these subjects differ from those found in idiopathic constipation.
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Affiliation(s)
- Gabrio Bassotti
- Gastroenterology and Hepatology Section, Department of Clinical and Experimental Medicine, University of Perugia, Perugia, Italy.
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Abstract
Over the lifetime of the animal, there are many changes in the function of the body’s organ systems. In the gastrointestinal tract there is a general modest decline in the function of the esophagus, stomach, colon, pancreas and liver. In the small intestine, there may be subtle alterations in the intestinal morphology, as well as a decline in the uptake of fatty acids and sugars. The malabsorption may be partially reversed by aging glucagon-like peptide 2 (GLP2) or dexamethasone. Modifications in the type of lipids in the diet will influence the intestinal absorption of nutrients: for example, in mature rats a diet enriched with saturated as compared with polysaturated fatty acids will enhance lipid and sugar uptake, whereas in older animals the opposite effect is observed. Thus, the results of studies of the intestinal adaptation performed in mature rats does not necessarily apply in older animals. The age-associated malabsorption of nutrients that occurs with aging may be one of the several factors which contribute to the malnutrition that occurs with aging.
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Sawhney R, Sehl M, Naeim A. Physiologic aspects of aging: impact on cancer management and decision making, part I. Cancer J 2006; 11:449-60. [PMID: 16393479 DOI: 10.1097/00130404-200511000-00004] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
A gradual diminution in the physiologic reserve or functional capacity over time is the characteristic hallmark of aging, and this has a direct impact on the choice of cancer therapy and its toxicity profile in elderly patients with cancer. With the expected rapid rise of the older population as a subgroup, oncologists will increasingly treat elderly patients. Provision of competent care to this increasing pool of older patients with cancer necessitates that oncology professionals become familiar with age-associated changes in organ physiology and their impact on cancer treatment and toxicity. In this comprehensive review, we have listed changes in cardiovascular, gastrointestinal, pulmonary, and renal physiology with aging. Also enumerated is the impact of these changes on cancer therapy and toxicity in each organ system-based section. Cardiovascular changes primarily lead to reduction of the cardiac functional reserve, with a consequent increase in the risk of congestive heart failure. Changes in gastrointestinal physiology lead to increased mucosal damage. A reduction in pulmonary reserve has implications for postradiation complications, and a decline in renal function leads to an increased potential for nephrotoxicity. These changes impair the ability of older patients with cancer to tolerate cancer therapy and increase their risk of toxicities. This may lead to an overall decline in functional status, resulting frailty, poor quality of life, and ultimately poor outcomes. Becoming familiar with age-related physiologic changes is the first step for oncologists seeking to better tailor their treatments. This, combined with adoption of some of the clinical interventions suggested in this review, can help better manage the geriatric oncology patient. Further research is necessary for the development of more specific evidence-based recommendations.
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Affiliation(s)
- Rishi Sawhney
- Division of Hematology-Oncology and Geriatrics, David Geffen School of Medicine, University of California, Los Angeles, California 90095-1687, USA
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Kaeberlein M, Hu D, Kerr EO, Tsuchiya M, Westman EA, Dang N, Fields S, Kennedy BK. Increased life span due to calorie restriction in respiratory-deficient yeast. PLoS Genet 2005; 1:e69. [PMID: 16311627 PMCID: PMC1287956 DOI: 10.1371/journal.pgen.0010069] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Accepted: 10/24/2005] [Indexed: 11/30/2022] Open
Abstract
A model for replicative life span extension by calorie restriction (CR) in yeast has been proposed whereby reduced glucose in the growth medium leads to activation of the NAD+-dependent histone deacetylase Sir2. One mechanism proposed for this putative activation of Sir2 is that CR enhances the rate of respiration, in turn leading to altered levels of NAD+ or NADH, and ultimately resulting in enhanced Sir2 activity. An alternative mechanism has been proposed in which CR decreases levels of the Sir2 inhibitor nicotinamide through increased expression of the gene coding for nicotinamidase, PNC1. We have previously reported that life span extension by CR is not dependent on Sir2 in the long-lived BY4742 strain background. Here we have determined the requirement for respiration and the effect of nicotinamide levels on life span extension by CR. We find that CR confers robust life span extension in respiratory-deficient cells independent of strain background, and moreover, suppresses the premature mortality associated with loss of mitochondrial DNA in the short-lived PSY316 strain. Addition of nicotinamide to the medium dramatically shortens the life span of wild type cells, due to inhibition of Sir2. However, even in cells lacking both Sir2 and the replication fork block protein Fob1, nicotinamide partially prevents life span extension by CR. These findings (1) demonstrate that respiration is not required for the longevity benefits of CR in yeast, (2) show that nicotinamide inhibits life span extension by CR through a Sir2-independent mechanism, and (3) suggest that CR acts through a conserved, Sir2-independent mechanism in both PSY316 and BY4742.
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Affiliation(s)
- Matt Kaeberlein
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, Washington, United States of America
| | - Di Hu
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Emily O Kerr
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Mitsuhiro Tsuchiya
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Eric A Westman
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Nick Dang
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Stanley Fields
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, Washington, United States of America
- Howard Hughes Medical Institute, University of Washington, Seattle, Washington, United States of America
| | - Brian K Kennedy
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
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