Age-related changes in the morphology of the myenteric plexus of the human colon

The human colon: Evidence for degenerative changes during aging and the physiological consequences

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.

Colon Volume by Computed Tomography and Scintigraphic Colonic Transit in Constipated Patients With or Without Redundant Colon

Redundant colon, also referred to as "dolichocolon," is an anatomical variant associated with elongation and redundancy thought to be associated with constipation, abdominal pain, and distention.1,2 Diagnosis requires radiological visualization of the non-dilated colon in situ via barium enema or abdominopelvic computed tomography (CT). Colonic redundancy is based on 3 criteria: sigmoid loop displaced cranially relative to the iliac crests (type 1); transverse colon caudal to the iliac crests (type 2); and redundant loops at the hepatic or splenic flexure (type 3).2 Rarely, dolichocolon may meet all 3 criteria.2.

Three-Dimensional Imaging of the Enteric Nervous System in Human Pediatric Colon Reveals New Features of Hirschsprung's Disease

BACKGROUND & AIMS

Hirschsprung's disease is defined by the absence of the enteric nervous system (ENS) from the distal bowel. Primary treatment is "pull-through" surgery to remove bowel that lacks ENS, with reanastomosis of "normal" bowel near the anal verge. Problems after pull-through are common, and some may be due to retained hypoganglionic bowel (ie, low ENS density). Testing this hypothesis has been difficult because counting enteric neurons in tissue sections is unreliable, even for experts. Tissue clearing and 3-dimensional imaging provide better data about ENS structure than sectioning.

METHODS

Regions from 11 human colons and 1 ileal specimen resected during Hirschsprung's disease pull-through surgery were cleared, stained with antibodies to visualize the ENS, and imaged by confocal microscopy. Control distal colon from people with no known bowel problems were similarly cleared, stained, and imaged.

RESULTS

Quantitative analyses of human colon, ranging from 3 days to 60 years old, suggest age-dependent changes in the myenteric plexus area, ENS ganglion area, percentage of myenteric plexus occupied by ganglia, neurons/mm2, and neuron Feret's diameter. Neuron counting using 3-dimensional images was highly reproducible. High ENS density in neonatal colon allowed reliable neuron counts using 500-μm2 × 500-μm2 regions (36-fold smaller than in adults). Hirschsprung's samples varied 8-fold in proximal margin enteric neuron density and had diverse ENS architecture in resected bowel.

CONCLUSIONS

Tissue clearing and 3-dimensional imaging provide more reliable information about ENS structure than tissue sections. ENS structure changes during childhood. Three-dimensional ENS anatomy may provide new insight into human bowel motility disorders, including Hirschsprung's disease.

Types of Neurons in the Human Colonic Myenteric Plexus Identified by Multilayer Immunohistochemical Coding

BACKGROUND AND AIMS

Gut functions including motility, secretion, and blood flow are largely controlled by the enteric nervous system. Characterizing the different classes of enteric neurons in the human gut is an important step to understand how its circuitry is organized and how it is affected by disease.

METHODS

Using multiplexed immunohistochemistry, 12 discriminating antisera were applied to distinguish different classes of myenteric neurons in the human colon (2596 neurons, 12 patients) according to their chemical coding. All antisera were applied to every neuron, in multiple layers, separated by elutions.

RESULTS

A total of 164 combinations of immunohistochemical markers were present among the 2596 neurons, which could be divided into 20 classes, with statistical validation. Putative functions were ascribed for 4 classes of putative excitatory motor neurons (EMN1-4), 4 inhibitory motor neurons (IMN1-4), 3 ascending interneurons (AIN1-3), 6 descending interneurons (DIN1-6), 2 classes of multiaxonal sensory neurons (SN1-2), and a small, miscellaneous group (1.8% of total). Soma-dendritic morphology was analyzed, revealing 5 common shapes distributed differentially between the 20 classes. Distinctive baskets of axonal varicosities surrounded 45% of myenteric nerve cell bodies and were associated with close appositions, suggesting possible connectivity. Baskets of cholinergic terminals and several other types of baskets selectively targeted ascending interneurons and excitatory motor neurons but were significantly sparser around inhibitory motor neurons.

CONCLUSIONS

Using a simple immunohistochemical method, human myenteric neurons were shown to comprise multiple classes based on chemical coding and morphology and dense clusters of axonal varicosities were selectively associated with some classes.

A Comprehensive Review on the Role of the Gut Microbiome in Human Neurological Disorders

The human body is full of an extensive number of commensal microbes, consisting of bacteria, viruses, and fungi, collectively termed the human microbiome. The initial acquisition of microbiota occurs from both the external and maternal environments, and the vast majority of them colonize the gastrointestinal tract (GIT). These microbial communities play a central role in the maturation and development of the immune system, the central nervous system, and the GIT system and are also responsible for essential metabolic pathways. Various factors, including host genetic predisposition, environmental factors, lifestyle, diet, antibiotic or nonantibiotic drug use, etc., affect the composition of the gut microbiota. Recent publications have highlighted that an imbalance in the gut microflora, known as dysbiosis, is associated with the onset and progression of neurological disorders. Moreover, characterization of the microbiome-host cross talk pathways provides insight into novel therapeutic strategies. Novel preclinical and clinical research on interventions related to the gut microbiome for treating neurological conditions, including autism spectrum disorders, Parkinson's disease, schizophrenia, multiple sclerosis, Alzheimer's disease, epilepsy, and stroke, hold significant promise. This review aims to present a comprehensive overview of the potential involvement of the human gut microbiome in the pathogenesis of neurological disorders, with a particular emphasis on the potential of microbe-based therapies and/or diagnostic microbial biomarkers. This review also discusses the potential health benefits of the administration of probiotics, prebiotics, postbiotics, and synbiotics and fecal microbiota transplantation in neurological disorders.

The gut microbiota and nervous system: Age-defined and age-defying

Even healthy older adults experience gastrointestinal (GI) and neurological changes. In fact, the aging process of these two systems are interrelated due the extensive, multifaceted communication network connecting them, termed the gut-brain axis. Age-related modification of the GI environment can influence the bacterial species that survive and thrive there. Additionally, the lifestyle common to older adults in the West, including sedentariness, polypharmacy, and a poor diet, can compound the effect of aging on the GI tract, gut microbiota, and nervous system. Emerging animal and human findings suggest that GI organisms play a major role in gut-brain communication, ultimately shaping neurological aging trajectories by either helping to maintain nervous system function into late life or promoting pathology. Aging and age-related behaviors help to define the gut microbiota's composition and function, but, conversely, the gut microbiota may help to determine late-life functionality and may be harnessed to limit the prevalence of steep neurological decline and diseases. Focusing primarily on clinical research, this review first defines the gut-brain axis, then details age-related GI and nervous system changes, and discusses the impact of age-related lifestyle factors on the GI and nervous systems. The remainder of this review describes cutting-edge research that positions the gut microbiota as an arbiter of age-related neurological decline.

Tau in the gut, does it really matter?

The enteric nervous system plays a critical role in the regulation of gastrointestinal tract functions and is often referred to as the 'second brain' because it shares many features with the central nervous system. These similarities include among others a large panel of neurotransmitters, a large population of glial cells and a susceptibility to neurodegeneration. This close homology between the central and enteric nervous systems suggests that a disease process affecting the central nervous system could also involve its enteric counterpart. This was already documented in Parkinson's disease, the most common synucleinopathy, in which alpha-synuclein deposits are reported in the enteric nervous system in the vast majority of patients. Tau is another key protein involved in neurodegenerative disorders of the brain. Whether changes in tau also occur in the enteric nervous system during gut or brain disorders has just begun to be explored. The scope of the present article is therefore to review existing studies on the expression and phosphorylation pattern of tau in the enteric nervous system under physiological and pathological conditions and to discuss the possible occurrence of 'enteric tauopathies'.

Severity of constipation related to palonosetron during first-line chemotherapy: a retrospective observational study

PURPOSE

Palonosetron, a long-acting 5-HT₃ receptor antagonist, is an effective antiemetic agent for chemotherapy-induced nausea and vomiting; however, it sometimes causes severe constipation. The aim of the present study was to evaluate the severity of palonosetron-related constipation.

METHODS

We retrospectively analyzed the incidence and severity of constipation after intravenous administration of 0.75-mg palonosetron in 150 chemotherapy-naïve patients who received first-line chemotherapy at Saga University Hospital. Constipation was classified into grades 1-5 according to the Common Terminology Criteria for Adverse Events version 5.0. Multiple logistic regression analysis was performed to identify factors associated with palonosetron-related worsening of constipation to grade 2 or higher.

RESULTS

Palonosetron significantly increased the incidence and severity of constipation (incidence: before vs. after palonosetron, 35.4% vs. 74.0%, p < 0.0001, and severity: before vs. after palonosetron, 26.7% and 8.7% in grades 1 and 2, respectively, vs. 46.7%, 23.3%, and 4.0% in grades 1, 2, and 3, respectively, p < 0.0001). Despite the use of laxatives, 4.0% of patients had grade 3 constipation requiring manual evacuation. Combination treatment with aprepitant (odds ratio (OR), 10.9; 95% confidence interval (CI), 1.3-90.0; p = 0.026) and older age (OR, 1.25; 95% CI, 1.01-1.57; p = 0.039) were factors associated with the severity of constipation.

CONCLUSION

Constipation was more severe in patients receiving combination treatment with aprepitant than in those treated with palonosetron alone. Older age was also associated with increased risk of severe palonosetron-related constipation. Identification of risk factors can help target risk-based laxative therapy.

Role of Sirtuins in Modulating Neurodegeneration of the Enteric Nervous System and Central Nervous System

Neurodegeneration of the central and enteric nervous systems is a common feature of aging and aging-related diseases, and is accelerated in individuals with metabolic dysfunction including obesity and diabetes. The molecular mechanisms of neurodegeneration in both the CNS and ENS are overlapping. Sirtuins are an important family of histone deacetylases that are important for genome stability, cellular response to stress, and nutrient and hormone sensing. They are activated by calorie restriction (CR) and by the coenzyme, nicotinamide adenine dinucleotide (NAD+). Sirtuins, specifically the nuclear SIRT1 and mitochondrial SIRT3, have been shown to have predominantly neuroprotective roles in the CNS while the cytoplasmic sirtuin, SIRT2 is largely associated with neurodegeneration. A systematic study of sirtuins in the ENS and their effect on enteric neuronal growth and survival has not been conducted. Recent studies, however, also link sirtuins with important hormones such as leptin, ghrelin, melatonin, and serotonin which influence many important processes including satiety, mood, circadian rhythm, and gut homeostasis. In this review, we address emerging roles of sirtuins in modulating the metabolic challenges from aging, obesity, and diabetes that lead to neurodegeneration in the ENS and CNS. We also highlight a novel role for sirtuins along the microbiota-gut-brain axis in modulating neurodegeneration.

Hirschsprung's Disease-Recent Understanding of Embryonic Aspects, Etiopathogenesis and Future Treatment Avenues

Hirschsprung's disease is a neurocristopathy, caused by defective migration, proliferation, differentiation and survival of neural crest cells, leading to gut aganglionosis. It usually manifests rapidly after birth, affecting 1 in 5000 live births around the globe. In recent decades, there has been a significant improvement in the understanding of its genetics and the association with other congenital anomalies, which share the pathomechanism of improper development of the neural crest. Apart from that, several cell populations which do not originate from the neural crest, but contribute to the development of Hirschsprung's disease, have also been described, namely mast cells and interstitial cells of Cajal. From the diagnostic perspective, researchers also focused on "Variants of Hirschsprung's disease", which can mimic the clinical signs of the disease, but are in fact different entities, with distinct prognosis and treatment approaches. The treatment of Hirschsprung's disease is usually surgical resection of the aganglionic part of the intestine, however, as many as 30-50% of patients experience persisting symptoms. Considering this fact, this review article also outlines future hopes and perspectives in Hirschsprung's disease management, which has the potential to benefit from the advancements in the fields of cell-based therapy and tissue engineering.

Paralytic ileus in the United States: A cross-sectional study from the national inpatient sample

Introduction:

Paralytic ileus is a common clinical condition leading to significant morbidity and mortality. Most studies to date have focused on postoperative ileus, a common but not exclusive cause of the condition. There are limited epidemiological data regarding the incidence and impact of paralytic ileus and its relationship to other clinical conditions. In this cross-sectional study, we analyzed national inpatient hospitalization trends, demographic variation, cost of care, length of stay, and mortality for paralytic ileus hospitalizations as a whole.

Methods:

The National Inpatient Sample database was used to identify all hospitalizations with the diagnosis of paralytic ileus (International Classification of Diseases, 9th Revision code 560.1) as primary or secondary diagnosis during the period from 2001 to 2011. Statistical analysis was performed using Cochran–Armitage trend test, Wilcoxon rank sum test, and Poisson regression.

Results:

In 2001, there were 362,561 hospitalizations with the diagnosis of paralytic ileus as compared to 470,110 in 2011 (p < 0.0001). The age group 65–79 years was most commonly affected by paralytic ileus throughout the study period. In-hospital all-cause mortality decreased from 6.03% in 2001 to 5.10% in 2011 (p < 0.0001). However, the average cost of care per hospitalization increased from US$19,739 in 2001 to US$26,198 in 2011 (adjusted for inflation, p < 0.0001).

Conclusion:

There was a significant rise in the number of hospitalizations of paralytic ileus with increased cost of care and reduced all-cause mortality.

Association between the severity of constipation and sarcopenia in elderly adults: A single-center university hospital-based, cross-sectional study

The aim of the present study was to investigate the association between the severity of constipation and sarcopenia in elderly adults. We conducted a single-center university hospital-based, retrospective cross-sectional study of consecutive outpatients aged ≥65 years from 2017 to 2020. Patients were included in the study if all of the following information were available from medical records: Patient's profile (age, sex, body mass index), laxative/prokinetics use, evaluation of sarcopenia, nutritional status, and questionnaires concerning the severity of constipation [Constipation Scoring System (CSS)], abdominal symptom-related quality of life (QOL) (Izumo scale) and stool shape [Bristol Stool Form Scale (BSFS)]. Multiple regression analysis of risk factors for high CSS score was performed. The results revealed that of the 310 eligible study subjects, [149 men (48.1%) and 161 women (51.9%); mean age, 75.7±6.1 years; mean body mass index, 23.0±3.6 kg/m²], sarcopenia was noted in 83 cases (26.8%). The CSS score was significantly higher in the sarcopenia group than that noted in the non-sarcopenia group (4.9±4.9 vs. 3.6±3.6, P=0.009). The CSS score was significantly associated with the albumin level (r=-0.148), lymphocyte count (r=-0.118), CONUT score (r=0.130), reflux-related QOL score (r=0.155), upper abdominal pain-related QOL score (r=0.171), fullness-related QOL score (r=0.299), constipation-related QOL score (r=0.615), diarrhea-related QOL score (r=0.235) and BSFS score (r=-0.114). In multiple regression analysis, independent predictors for CSS score were sarcopenia [standardized partial regression coefficient (β)=0.107, P=0.032], constipation-related QOL score (β=0.537, P<0.001), laxative/prokinetics use (β=0.211, P<0.001) and BSFS score (β=-0.098, P=0.031) (R²=0.436). In conclusion, sarcopenia, constipation-related QOL score, laxative/prokinetics use and BSFS score are associated with the severity of constipation in elderly adults.

Common Urinary and Bowel Disorders in the Geriatric Population

The prevalence of urinary incontinence and other lower urinary tract symptoms increases with older age. These symptoms are more noticeable in men after the seventh decade of life and in women after menopause. Constipation and fecal incontinence are major causes of symptoms in elderly patients and can significantly impair quality of life. This article summarizes the current literature regarding the occurrence and implications of lower urinary tract and bowel symptoms in the geriatric population.

Risks, time trends, and mortality of colonoscopy-induced perforation in hospitalized patients

BACKGROUND AND AIM

Colonic perforation is a rare complication of colonoscopy and ranges from 0% to 1% in all patients undergoing colonoscopy. The aim of this study was to assess the time trends, risk factors, and mortality associated with colonoscopy-induced perforation (CIP) in hospitalized patients as the data are limited.

METHODS

Data are obtained from the Nationwide Inpatient Sample database to identify hospitalized patients between 2005 and 2014 that had CIP. Various factors like age and gender were assessed for association with CIP, followed by univariate and multivariate regression analyses.

RESULTS

A total of 2 651 109 patients underwent inpatient colonoscopy between 2005 and 2014, and 4567 (0.2%) of the patients had CIP. Overall, incidence of CIP has increased from 2005 to 2014 (0.1% to 0.3%) (P < 0.001). On multivariate analysis, the adjusted odds ratio (OR) for CIP was highest in Caucasian race (OR: 1.49 [1.09, 2.06]), followed by after polypectomy, history of inflammatory bowel disease, end-stage renal disease, and age > 65 years (OR [95% CI] of 1.35 [1.23, 1.47], 1.34 [1.17, 1.53], 1.28 [1.02, 1.62], and 1.21 [1.11, 1.33], respectively) (all P < 0.05). CIP group had 33% less obesity (OR [95% CI]: 0.77 [0.65-0.9], P = 0.002) and 13-fold higher mortality (0.5% vs 8.1%) (P < 0.001) as compared to patients without CIP. The CIP-associated mortality ranged from 2% to 8% and remained stable throughout the study period.

CONCLUSIONS

Our study suggests that the risk of CIP was highest in elderly patients, Caucasians, those with inflammatory bowel disease, end-stage renal disease, and after polypectomy. Recognizing the factors associated with CIP may lead to informed discussion about risks and benefits of inpatient colonoscopy.

Hypoganglionosis in the gastric antrum causes delayed gastric emptying

BACKGROUND

Enteric nervous system (ENS) abnormalities have been implicated in delayed gastric emptying but studies exploring potential treatment options are limited by the lack of an experimental animal model. We examined the ENS abnormalities in the mouse stomach associated with aging, developed a novel model of gastroparesis, and established a new approach to measure gastric emptying.

METHODS

A modified gastric emptying assay was developed, validated in nNOS ^-/- mice, and tested in mice at multiple ages. Age-related changes in ENS structure were analyzed by immunohistochemistry. Gastric aganglionosis was generated in Wnt1-iDTR mice using focal administration of diphtheria toxin (DT) into the anterior antral wall.

KEY RESULTS

Older mice (>5 months) exhibit hypoganglionosis in the gastric antrum and a decreased proportion of nNOS neurons as compared to younger mice (age 5-7 weeks). This was associated with a significant age-dependent decrease in liquid and solid gastric emptying. A novel model of gastric antrum hypoganglionosis was established using neural crest-specific expression of diphtheria toxin receptor. In this model, a significant reduction in liquid and solid gastric emptying is observed.

CONCLUSIONS & INFERENCES

Older mice exhibit delayed gastric emptying associated with hypoganglionosis and a reduction in nNOS-expressing neurons in the antrum. The causal relationship between antral hypoganglionosis and delayed gastric emptying was verified using a novel experimental model of ENS ablation. This study provides new information regarding the pathogenesis of delayed gastric emptying and provides a robust model system to study this disease and develop novel treatments.

Gastrointestinal Tract Disorders in Older Age

Considering an increase in the life expectancy leading to a rise in the elderly population, it is important to recognize the changes that occur along the process of aging. Gastrointestinal (GI) changes in the elderly are common, and despite some GI disorders being more prevalent in the elderly, there is no GI disease that is limited to this age group. While some changes associated with aging GI system are physiologic, others are pathological and particularly more prevalent among those above age 65 years. This article reviews the most important GI disorders in the elderly that clinicians encounter on a daily basis. We highlight age-related changes of the oral cavity, esophagus, stomach, small and large bowels, and the clinical implications of these changes. We review epidemiology and pathophysiology of common diseases, especially as they relate to clinical manifestation in elderly. Details regarding management of specific disease are discussed in detail if they significantly differ from the management for younger groups or if they are associated with significant challenges due to side effects or polypharmacy. Cancers of GI tract are not included in the scope of this article.

Gut microbiome and aging: Physiological and mechanistic insights

The development of human gut microbiota begins as soon as the neonate leaves the protective environment of the uterus (or maybe in-utero) and is exposed to innumerable microorganisms from the mother as well as the surrounding environment. Concurrently, the host responses to these microbes during early life manifest during the development of an otherwise hitherto immature immune system. The human gut microbiome, which comprises an extremely diverse and complex community of microorganisms inhabiting the intestinal tract, keeps on fluctuating during different stages of life. While these deviations are largely natural, inevitable and benign, recent studies show that unsolicited perturbations in gut microbiota configuration could have strong impact on several features of host health and disease. Our microbiota undergoes the most prominent deviations during infancy and old age and, interestingly, our immune health is also in its weakest and most unstable state during these two critical stages of life, indicating that our microbiota and health develop and age hand-in-hand. However, the mechanisms underlying these interactions are only now beginning to be revealed. The present review summarizes the evidences related to the age-associated changes in intestinal microbiota and vice-versa, mechanisms involved in this bi-directional relationship, and the prospective for development of microbiota-based interventions such as probiotics for healthy aging.

Differences in innervated neurons of the internal anal sphincter based on age and sex: A histological study

AIM

Previous studies have shown sex and age differences in anal sphincter function, but few morphological studies have focused on the quality and quantity of the nerves that control the sphincter muscles. The present study aimed to determine whether there are morphological and quantitative sex and age differences in the nerves in the conjoined longitudinal muscle.

METHODS

This was a single-center, retrospective study using surgical specimens from 44 patients who underwent abdominoperineal resection between 2003 and 2012. Hematoxylin-eosin- and S-100-stained peripheral nerves (nerve fibers and ganglion cells) in the conjoined longitudinal muscle beneath the dentate line were observed microscopically. A qualitative examination assessed the degeneration score, which was based on the presence or absence of karyopyknosis, vacuolar degeneration, acidophilic degeneration of the cytoplasm, denucleation and adventitial neuronal changes. For quantitative examinations, each neuronal and muscular area was traced to calculate the neuronal area ratio in S-100-immunostained photomicrographs at the observation site.

RESULTS

Women had a significantly lower quantity of nerves than men. Older individuals (aged ≥80 years) had a significantly lower quantity of nerves than younger individuals. Furthermore, older individuals tended to show greater morphological changes that appeared to be a result of degeneration.

CONCLUSIONS

The present findings suggest that anal hypofunction in women and older individuals might result from differences in the quantity and quality of the neurons controlling the anal sphincter muscle. Geriatr Gerontol Int 2018; 18: 495-500.

Morphological changes in peri-prostatic sympathetic ganglion cells in aging males

A significant part of morbidity in elderly male patients involves the pelvic organs and their autonomic neural regulation. The aim of the current study was to report the histopathological changes in the peri-prostatic ganglia in elderly males. The sympathetic ganglia from 36 prostatectomy specimens, 26 due to carcinoma of the prostate and 10 prostates from total cystectomies for transitional cell carcinoma, were examined. The age range was 54-88 years. A total of 5,075 ganglion cells were counted in all the specimens. Pathological changes were identified in 1,696 neuron cells as follows: Neuronophagia in 746 neuron cells, neuron cell vacuolization (330 cells), satellite cells vacuolization (423 cells), cell pyknosis (148 cells) and nageotte nodules (49 cells). A number of these changes increased with age. All the changes were more marked in the peri-prostatic ganglion cells of patients with prostatic adenocarcinoma compared with those with benign prostate hyperplasia, which may be due to local environmental changes associated with the presence of malignancy.

Understanding the gastrointestinal tract of the elderly to develop dietary solutions that prevent malnutrition

Although the prevalence of malnutrition in the old age is increasing worldwide a synthetic understanding of the impact of aging on the intake, digestion, and absorption of nutrients is still lacking. This review article aims at filling the gap in knowledge between the functional decline of the aging gastrointestinal tract (GIT) and the consequences of malnutrition on the health status of elderly. Changes in the aging GIT include the mechanical disintegration of food, gastrointestinal motor function, food transit, chemical food digestion, and functionality of the intestinal wall. These alterations progressively decrease the ability of the GIT to provide the aging organism with adequate levels of nutrients, what contributes to the development of malnutrition. Malnutrition, in turn, increases the risks for the development of a range of pathologies associated with most organ systems, in particular the nervous-, muscoskeletal-, cardiovascular-, immune-, and skin systems. In addition to psychological, economics, and societal factors, dietary solutions preventing malnutrition should thus propose dietary guidelines and food products that integrate knowledge on the functionality of the aging GIT and the nutritional status of the elderly. Achieving this goal will request the identification, validation, and correlative analysis of biomarkers of food intake, nutrient bioavailability, and malnutrition.

Epidemiology and management of chronic constipation in elderly patients

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.

Severe adverse outcomes of endoscopic perforations in patients with and without IBD

BACKGROUND

Endoscopy-associated perforation (EAP) is a dreaded adverse event with significant morbidity and even mortality. Whether EAP in patients with inflammatory bowel disease (IBD) is associated with worse outcomes is not known. We aimed to assess the frequency of perforations in patients undergoing lower gastrointestinal (GI) endoscopies and compare the risk factors and perforation-associated complications (PAC) in patients with IBD with those without IBD.

METHODS

In this case-control study, we identified patients with lower GI EAP from January 2002 to June 2011. PAC was defined as EAP-associated death, colectomy with ileostomy, and bowel resection with/without diverting ostomy. Twenty-nine demographic, clinical, endoscopic, and surgical features were evaluated in univariable and multivariable analyses.

RESULTS

A total of 217,334 lower GI endoscopies were performed (IBD, N = 9518 and non-IBD, N = 207,816). Eighty-four patients with EAP were included. The rate of perforation was 18.91 per 10,000 and 2.50 per 10,000 procedures for IBD and non-IBD endoscopy, respectively. PAC occurred in 59 patients (70.2%) with death in 4 (4.8%) and bowel resection with or without ostomy in 55 (65.5%) (total colectomy with ileostomy, n = 3; resection with diversion and secondary anastomosis, n = 28; and resection with primary anastomosis, n = 24). On multivariable analysis, the use of systemic corticosteroids at the time of endoscopy was associated with 13 times greater risk for PAC (13.5 [95% confidence interval, 1.3-1839.7] P = 0.007), whereas IBD was not found to be associated with an increased risk for PAC (0.69 [95% confidence interval, 0.23-2.1] P = 0.52).

CONCLUSIONS

Patients with IBD have a higher frequency of EAP than those without IBD. Endoscopists need to be cautious while performing a lower GI endoscopy in patients taking systemic corticosteroids.

Age-related gene expression analysis in enteric ganglia of human colon after laser microdissection

The enteric nervous system (ENS) poses the intrinsic innervation of the gastrointestinal tract and plays a critical role for all stages of postnatal life. There is increasing scientific and clinical interest in acquired or age-related gastrointestinal dysfunctions that can be manifested in diseases such as gut constipation or fecal incontinence. In this study, we sought to analyze age-dependent changes in the gene expression profile of the human ENS, particularly in the myenteric plexus. Therefore, we used the laser microdissection technique which has been proven as a feasible tool to analyze distinct cell populations within heterogeneously composed tissues. Full biopsy gut samples were prepared from children (4-12 months), middle aged (48-58 years) and aged donors (70-95 years). Cryosections were histologically stained with H&E, the ganglia of the myenteric plexus identified and RNA isolated using laser microdissection technique. Quantitative PCR was performed for selected neural genes, neurotransmitters and receptors. Data were confirmed on protein level using NADPH-diaphorase staining and immunohistochemistry. As result, we demonstrate age-associated alterations in site-specific gene expression pattern of the ENS. Thus, in the adult and aged distal parts of the colon a marked decrease in relative gene expression of neural key genes like NGFR, RET, NOS1 and a concurrent increase of CHAT were observed. Further, we detected notable regional differences of RET, CHAT, TH, and S100B comparing gene expression in aged proximal and distal colon. Interestingly, markers indicating cellular senescence or oxidative stress (SNCA, CASP3, CAT, SOD2, and TERT) were largely unchanged within the ENS. For the first time, our study also describes the age-dependent expression pattern of all major sodium channels within the ENS. Our results are in line with previous studies showing spatio-temporal differences within the mammalian ENS.

Chagasic megacolon: enteric neurons and related structures

Megacolon, the irreversible dilation of a colonic segment, is a structural sign associated with various gastrointestinal disorders. In its hereditary, secondary form (e.g. in Hirschsprung's disease), dilation occurs in an originally healthy colonic segment due to an anally located, aganglionic zone. In contrast, in chronic Chagas' disease, the dilated segment itself displays pathohistological changes, and the earliest and most prominent being found was massive loss of myenteric neurons. This neuron loss was partial and selective, i.e. some neurons containing neuronal nitric oxide synthase and/or vasoactive intestinal peptide (VIP) were spared from neuron death. This disproportionate survival of inhibitory neurons, however, did not completely correlate with the calibre change along the surgically removed, megacolonic segments. A better correlation was observed as to potentially contractile muscle tissue elements and the interstitial cells of Cajal. Therefore, the decreased densities of α-smooth muscle actin- and c-kit-immunoreactive profiles were estimated along resected megacolonic segments. Their lowest values were observed in the megacolonic zones itself, whereas less pronounced decreases were found in the non-dilated, transitional zones (oral and anal to dilation). In contrast to the myenteric plexus, the submucosal plexus displayed only a moderate neuron loss. Neurons co-immunoreactive for VIP and calretinin survived disproportionately. As a consequence, these neurons may have contributed to maintain the epithelial barrier and allowed the chagasic patients to survive for decades, despite their severe disturbance of colonic motility. Due to its neuroprotective and neuroeffectory functions, VIP may play a key role in the development and duration of chagasic megacolon.

Anorectal physiology and pathophysiology in the elderly

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.

Urogenital consequences in ageing women

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.

Cellular changes in the enteric nervous system during ageing

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.

Parkinson's disease is not associated with gastrointestinal myenteric ganglion neuron loss

Gastrointestinal dysfunction is a prominent non-motor feature of Parkinson's disease (PD) that contributes directly to the morbidity of patients, complicates management of motor symptoms, and may herald incipient PD in patients without motor disability. Although PD has traditionally been considered a disease of dopaminergic neurons in the substantia nigra, analyses of gastrointestinal samples from PD patients have consistently revealed pathology in the enteric nervous system. The relationship of PD pathology to GI dysmotility is poorly understood, and this lack of understanding has led to limited success in developing treatments for PD-related GI symptoms. We have quantitatively compared myenteric neuron density and relative abundance of NO, VIP, and catecholamine neurons between patients with PD and control individuals along the length of the GI tract. In addition, we have examined the frequency of GI α-synuclein neuritic pathology and its co-localization with the same neuronal markers. We have included a comparison with a small population of patients with incidental Lewy bodies found at autopsy. These data indicate that there is no neuronal loss in the myenteric plexus in PD. Lewy body pathology parallels parasympathetic autonomic input from the dorsal motor nucleus of the vagus, not the distribution of extrinsic sympathetic input or intrinsic enteric neurons, and is only rarely co-localized with tyrosine hydroxylase. These data provide a critical background to which further analyses of the effect of PD on the GI tract may be compared and suggest that neuropathology in myenteric neurons is unlikely to be a causative factor in PD-related GI dysmotility.

Serotonin: from top to bottom

Serotonin is a monoamine neurotransmitter, which is phylogenetically conserved in a wide range of species from nematodes to humans. In mammals, age-related changes in serotonin systems are known risk factors of age-related diseases, such as diabetes, faecal incontinence and cardiovascular diseases. A decline in serotonin function with aging would be consistent with observations of age-related changes in behaviours, such as sleep, sexual behaviour and mood all of which are linked to serotonergic function. Despite this little is known about serotonin in relation to aging. This review aims to give a comprehensive analysis of the distribution, function and interactions of serotonin in the brain; gastrointestinal tract; skeletal; vascular and immune systems. It also aims to demonstrate how the function of serotonin is linked to aging and disease pathology in these systems. The regulation of serotonin via microRNAs is also discussed, as are possible applications of serotonergic drugs in aging research and age-related diseases. Furthermore, this review demonstrates that serotonin is potentially involved in whole organism aging through its links with multiple organs, the immune system and microRNA regulation. Methods to investigate these links are discussed.

Morphological and quantitative study of the myenteric plexus in the human tenia coli

The longitudinal muscle in the large intestine in humans and some other mammalian species is concentrated in regions known as "tenia coli." The myenteric plexus under the tenia is believed to be highly developed to control the adjacent large muscle mass, however, data on the innervation of this region are very scarce. We used whole mount preparations of human colon to characterize the organization of the myenteric plexus under the tenia coli (UT) and compared it with the plexus between the tenia (BT). Using histochemical staining for NADPH diaphorase, we found that the meshwork UT was 50% denser than BT, and that the ganglia UT were 30% wider. The density and size of the NADPH-d positive neurons UT were similar to those of BT. We conclude that the myenteric plexus UT is considerably more developed than BT, and suggest to understand the control of colonic motility, the myenteric plexus UT needs to be further investigated.

Prevalence and risk factors for colonic perforation during colonoscopy in hospitalized end-stage renal disease patients on hemodialysis

BACKGROUND AND AIMS

Colonic perforation is a rare complication during colonoscopy. A recent single center study reported a high incidence of colonic perforation in end-stage renal disease (ESRD) patients on hemodialysis (HD) who underwent colonoscopy. We sought to determine nationwide, population-based prevalence in rates of colonic perforation during colonoscopy among ESRD inpatients on HD in the US, and to assess risk factors for colonic perforation in this patient population.

METHODS

We obtained patient data from the Nationwide Inpatient Sample and used the International Classification of Diseases, the 9th revision, clinical modification codes, to identify ESRD patients on HD who had undergone colonoscopy in 2006. The control group consisted of inpatients who had colonoscopy without ESRD.

RESULTS

Colonic perforations occurred in 51/17,000 ESRD hospitalizations on HD (0.3%) and 3,951/564,428 controls without ESRD (0.7%). The risk of colonic perforation among the study group was not significantly higher than the control group even after adjusting for patient demographics like age, gender and comorbid conditions (adjusted odds ratio [aOR] -0.55; 95% confidence interval [CI], 0.30-0.97). Older age (OR -1.007; 95% CI, 1.002-1.011) and female gender (OR -1.18; 95% CI, 1.03-1.36) were identified as independent risk factors for the risk of perforation in this population group.

CONCLUSIONS

There appeared no increased risk of colonic perforation during colonoscopy among inpatients who received HD in our study. Increasing age and female patients appeared to be associated with procedure-related colonic perforation.

Effect of ageing on colonic mucosal regeneration

The physiologic and pathologic cellular and molecular changes occurring with age in the human colon affect both the inflammatory process leading to mucosal injury and the regenerative capacity of the epithelium. On the one hand, age-related telomere shortening and inflamm-ageing may lead to the development of colonic inflammation, which results in epithelial damage. On the other hand, the altered migration and function of regenerative stem cells, the age-related methylation of mucosal healing-associated genes, together with the alterations of growth factor signaling with age, may be involved in delayed mucosal regeneration. The connections of these alterations to the process of ageing are not fully known. The understanding and custom-tailored modification of these mechanisms are of great clinical importance with regard to disease prevention and modern therapeutic strategies. Here, we aim to summarize the age-related microscopic and molecular changes of the human colon, as well as their role in altered mucosal healing.

Prevalence and risk factors for colonic perforation during colonoscopy in hospitalized inflammatory bowel disease patients

BACKGROUND

Colonic perforation is a rare complication associated with colonoscopy. There are no population-based studies on the risk of colonic perforation in IBD inpatients.

AIM

We sought to determine the prevalence of colonic perforation during colonoscopy among IBD inpatients, and to assess its risk factors.

MATERIALS AND METHODS

We obtained patient data from the Nationwide Inpatient Sample and used the International Classification of Diseases, the 9th revision, clinical modification codes, to identify IBD patients who had undergone colonoscopy in 2006. The control group consisted of inpatients who had colonoscopy without IBD.

RESULTS

Colonic perforation occurred in 344/33,732 (1%) IBD hospitalizations and in 3658/578,458 (0.6%) controls without IBD (P=0.0001). The risk of colonic perforation in the IBD group was significantly higher than the control group even after adjusting for age, gender, comorbidities and endoscopic interventions including endoscopic dilations and colonoscopic polypectomy, with adjusted odds ratio (aOR) of 1.83 (95% confidence interval [CI]: 1.40, 2.38). In addition, older age (aOR=1.01, 95% CI: 1.006-1.015), female gender (aOR=1.20; 95% CI: 1.04, 1.38), and therapeutic endoscopic dilation (aOR=6.63; 95% CI: 3.95, 11.11) were independent risk factors for perforation. Colonoscopic biopsy, polypectomy and the presence of comorbidities did not increase the risk of perforation.

CONCLUSIONS

There appears to be a higher risk of colonoscopy-associated perforation in IBD inpatients than non-IBD controls. In addition, older age, female patients and endoscopic dilations appeared to be associated with an increased risk for perforation.

Quantitation of cellular components of the enteric nervous system in the normal human gastrointestinal tract--report on behalf of the Gastro 2009 International Working Group

BACKGROUND

Patients with gastrointestinal neuromuscular diseases may undergo operative procedures that yield tissue appropriate to diagnosis of underlying neuromuscular pathology. Critical to accurate diagnosis is the determination of limits of normality based on the study of control human tissues. Although robust diagnostic criteria exist for many qualitative alterations in the neuromuscular apparatus, these do not include quantitative values due to lack of adequate control data.

PURPOSE

The aim of this report was to summarize all relevant available published quantitative data for elements of the human enteric nervous system (neuronal cell bodies, glial cells, and nerve fibers) from the perspective of the practicing pathologist. Forty studies meeting inclusion criteria were systematically reviewed with data tabulated in detail and discussed in the context of methodological variations and limitations. The results reveal a lack of concordance between observations of different investigators resulting in data insufficient to produce robust normal ranges. This diversity highlights the need to standardize the way pathologists collect, process, and quantitate neuronal and glial elements in enteric neuropathologic samples, as suggested by recent international guidelines on gastrointestinal neuromuscular pathology.

Can "functional" constipation be considered as a form of enteric neuro-gliopathy?

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.

Partial, selective survival of nitrergic neurons in chagasic megacolon

One frequent chronic syndrome of Chagas’ disease is megacolon, an irreversible dilation of a colonic segment. Extensive enteric neuron loss in the affected segment is regarded as key factor for deficient motility. Here, we assessed the quantitative balance between cholinergic and nitrergic neurons representing the main limbs of excitatory and inhibitory colonic motor innervation, respectively. From surgically removed megacolonic segments of four patients, each three myenteric wholemounts (from non-dilated oral, megacolonic and non-dilated anal parts) was immunohistochemically triple-stained for choline acetyltransferase, neuronal nitric oxide synthase (NOS) and the panneuronal human neuronal protein Hu C/D. Degenerative changes were most pronounced in the megacolonic and anal regions, e.g. bulked, honeycomb-like ganglia with few neurons which were partly enlarged or atrophic or vacuolated. Neuron counts from each 15 ganglia of 12 megacolonic wholemounts were compared with those of 12 age- and region-matched controls. Extensive neuron loss, mainly in megacolonic and anal wholemounts, was obvious. In all three regions derived from megacolonic samples, the proportion of NOS-positive neurons (control: 55%) was significantly increased: in non-dilated oral parts to 61% (p = 0.003), in megacolonic regions to 72% (p < 0.001) and in non-dilated anal regions to 78% (p < 0.001). We suggest the chronic dilation of megacolonic specimens to be due to the preponderance of the nitrergic, inhibitory input to the intestinal muscle. However, the observed neuronal imbalance was not restricted to the dilated regions: the non-dilated anal parts may be innervated by ascending, cholinergic axons emerging from less affected, more anally located regions.

Recordings from human myenteric neurons using voltage-sensitive dyes

Voltage-sensitive dye (VSD) imaging became a powerful tool to detect neural activity in the enteric nervous system, including its routine use in submucous neurons in freshly dissected human tissue. However, VSD imaging of human myenteric neurons remained a challenge because of limited visibility of the ganglia and dye accessibility. We describe a protocol to apply VSD for recordings of human myenteric neurons in freshly dissected tissue and myenteric neurons in primary cultures. VSD imaging of guinea-pig myenteric neurons was used for reference. Electrical stimulation of interganglionic fiber tracts and exogenous application of nicotine or elevated KCl solution was used to evoke action potentials. Bath application of the VSDs Annine-6Plus, Di-4-ANEPPS, Di-8-ANEPPQ, Di-4-ANEPPDHQ or Di-8-ANEPPS revealed no neural signals in human tissue although most of these VSD worked in guinea-pig tissue. Unlike methylene blue and FM1-43, 4-Di-2-ASP did not influence spike discharge and was used in human tissue to visualize myenteric ganglia as a prerequisite for targeted intraganglionic VSD application. Of all VSDs, only intraganglionic injection of Di-8-ANEPPS by a volume controlled injector revealed neuronal signals in human tissue. Signal-to-noise ratio increased by addition of dipicrylamine to Di-8-ANEPPS (0.98±0.16 vs. 2.4±0.62). Establishing VSD imaging in primary cultures of human myenteric neurons led to a further improvement of signal-to-noise ratio. This allowed us to routinely record spike discharge after nicotine application. The described protocol enabled reliable VSD recordings from human myenteric neurons but may also be relevant for the use of other fluorescent dyes in human tissues.

Decrease in nerve fibre density in human sigmoid colon circular muscle occurs with growth but not aging

BACKGROUND

Studies in animals suggest that enteric neurons decrease in density or number with increasing age. Neurons containing nitric oxide (NO), vasoactive intestinal peptide (VIP) and Substance P (SP) have been implicated. In human large intestine, NO-utilizing neurons decrease during childhood or early adulthood but it is not known if the innervation of the muscle changes. This study examined the density of nerve fibres containing these transmitters in sigmoid colon circular muscle from children and adults.

METHODS

Fluorescence immunohistochemistry using antibodies to neuronal NO synthase (nNOS), VIP and SP was performed on sigmoid colon from 18 adults with colorectal cancer, two children with familial adenomatous polyposis, and normal colon from nine children with Hirschsprung's disease. The percentage area of immunoreactive (IR) nerve fibres containing each transmitter in circular muscle was quantified in confocal images.

KEY RESULTS

In the adult sigmoid colon circular muscle, the percentage area of nerve fibres containing nNOS>VIP>SP (6 : 2 : 1). Paediatric groups had significantly higher percentage area of nerve fibres containing nNOS, VIP or SP-IR than adults, with the decrease in nerve fibre density occurring from birth to 30 years. Circular muscle thickness increased between 12 and 30 years. Total nerve fibre area remained constant, while the muscle increased in thickness.

CONCLUSIONS & INFERENCES

In human sigmoid colon circular muscle, there are reductions in nNOS-, VIP- and SP-IR nerve fibre density with growth from newborn to late adolescence but little further change with aging. The reduction in nerve density is due to an increase in circular muscle thickness rather than a loss of nerve fibres.

Chronic constipation in the elderly

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.

Effect of age on the enteric nervous system of the human colon

The effect of age on the anatomy and function of the human colon is incompletely understood. The prevalence of disorders in adults such as constipation increase with age but it is unclear if this is due to confounding factors or age-related structural defects. The aim of this study was to determine number and subtypes of enteric neurons and neuronal volumes in the human colon of different ages. Normal colon (descending and sigmoid) from 16 patients (nine male) was studied; ages 33-99. Antibodies to HuC/D, choline acetyltransferase (ChAT), neuronal nitric oxide synthase (nNOS), and protein gene product 9.5 were used. Effect of age was determined by testing for linear trends using regression analysis. In the myenteric plexus, number of Hu-positive neurons declined with age (slope = -1.3 neurons/mm/10 years, P = 0.03). The number of ChAT-positive neurons also declined with age (slope = -1.1 neurons/mm/10 years of age, P = 0.02). The number of nNOS-positive neurons did not decline with age. As a result, the ratio of nNOS to Hu increased (slope = 0.03 per 10 years of age, P = 0.01). In the submucosal plexus, the number of neurons did not decline with age (slope = -0.3 neurons/mm/10 years, P = 0.09). Volume of nerve fibres in the circular muscle and volume of neuronal structures in the myenteric plexus did not change with age. In conclusion, the number of neurons in the human colon declines with age with sparing of nNOS-positive neurons. This change was not accompanied by changes in total volume of neuronal structures suggesting compensatory changes in the remaining neurons.

Quantitative evaluation of myenteric ganglion cells in normal human left colon: implications for histopathological analysis

The analysis of myenteric neurons is becoming increasingly important for the assessment of enteric nervous system injury and degeneration occurring in motor disorders of the gut. Limited information is presently available on the quantitative estimation of myenteric neurons and glial cells in paraffin-embedded colonic sections; additional data would be useful for diagnostic purposes. In this morphometric study, we performed immunohistochemistry to count myenteric neurons and glial cells in paraffin sections of human colon. Serial cross sections of formalin-fixed paraffin-embedded full-thickness normal human left colon (n = 10, age-range: 50-72 years) were examined. HuC/D and S100beta antigens were found to be the best markers for the detection of neurons and glial cells, respectively. Significant correlations were noted between the numbers of neurons/glial cells and the respective myenteric ganglion areas. These findings suggest that HuC/D-S100beta-immunostained paraffin cross sections of human colon can be regarded as valuable tools for the quantitative estimation of myenteric neurons and glial cells. Based on the present method, only a limited number of paraffin sections are needed for reliable quantitative assessments of myenteric ganglion cells, thus allowing fast and simple approaches in the settings of the histopathological diagnosis of colonic motility disorders and retrospective evaluations of pathological archival tissue specimens.

Quantitative assessment of glial cells in the human and guinea pig enteric nervous system with an anti-Sox8/9/10 antibody

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.

Exercise reduces inhibitory neuroactivity and protects myenteric neurons from age-related neurodegeneration

The practice of regular exercise is indicated to prevent some motility disturbances in the gastrointestinal tract, such as constipation, during aging. The motility alterations are intimately linked with its innervations. The goal of this study is to determine whether a program of exercise (running on the treadmill), during 6 months, has effects in the myenteric neurons (NADH- and NADPH-diaphorase stained neurons) in the colon of rats during aging. Male Wistar rats 6 months (adult) and 12 months (middle-aged) old were divided into 3 different groups: AS (adult sedentary), MS (middle-aged sedentary) and MT (middle-aged submitted to physical activity). The aging did not cause a decline significant (p>0.05) of the number of NADH-diaphorase stained neurons in sedentary rats (AS vs. MS group). In contrast, a decline of 31% was observed to NADPH-diaphorase stained neurons. Thus, animals that underwent physical activity (AS vs. MT group) rescued neurons from degeneration caused by aging (total number, density and profile of neurons did not change with age--NADH-diaphorase method). On the other hand, physical activity augmented the decline of NADPH-diaphorase positive neurons (total number, density and profile of neurons decreased). Collectively, the results show that exercise inhibits age-related decline of myenteric neurons however, exercise augments the decline of neurons with inhibitory activity (nitric oxide) in the colon of the rats.

Pathophysiology of constipation in the older adult

This review provides information on the definition of constipation, normal continence and defecation and a description of the pathophysiologic mechanisms of constipation. In addition, changes in the anatomy and physiology of the lower gastrointestinal tract associated with aging that may contribute to constipation are described. MEDLINE (1966-2007) and CINAHL (1980-2007) were searched. The following MeSH terms were used: constipation/etiology OR constipation/physiology OR constipation/physiopathology) AND (age factors OR aged OR older OR 80 and over OR middle age). Constipation is not well defined in the literature. While self-reported constipation increases with age, findings from a limited number of clinical studies that utilized objective measures do not support this association. Dysmotility and pelvic floor dysfunction are important mechanisms associated with constipation. Changes in GI function associated with aging appear to be relatively subtle based on a limited amount of conflicting data. Additional research is warranted on the effects of aging on GI function, as well as on the timing of these changes.

Enteric neurodegeneration in ageing

The objective of this article is to review the clinical presentation and neurobiology of degeneration of the enteric nervous system with emphasis on human data where available. Constipation, incontinence and evacuation disorders are frequently encountered in the ageing population. Healthy lower gastrointestinal function is essential for successful ageing as it is critical to maintaining independence and autonomy to pursue further activity. One clinical expression of enteric neurodegeneration is constipation. However, the aetiology may be multifactorial as disturbances of epithelial, muscle or neural function may all result from neurodegeneration. There is evidence of loss of excitatory (e.g. cholinergic) enteric neurons and interstitial cells of Cajal, whereas inhibitory (including nitrergic) neurons appear unaffected. Understanding neurodegeneration in the enteric nervous system is key to developing treatments to reverse it. Neurotrophins have been shown to accelerate colonic transit and relieve constipation in the medium term; they are also implicated in maintenance programmes in adult enteric neurons through a role in antioxidant defence. However, their effects in ageing colon require further study. There is evidence that 5-HT(2) and 5-HT(4) mechanisms are involved in development, maintenance and survival of enteric neurons. Further research is needed to understand and potentially reverse enteric neurodegeneration.

Enteric neurodegeneration in ageing

The objective of this article is to review the clinical presentation and neurobiology of degeneration of the enteric nervous system with emphasis on human data where available. Constipation, incontinence and evacuation disorders are frequently encountered in the ageing population. Healthy lower gastrointestinal function is essential for successful ageing as it is critical to maintaining independence and autonomy to pursue further activity. One clinical expression of enteric neurodegeneration is constipation. However, the aetiology may be multifactorial as disturbances of epithelial, muscle or neural function may all result from neurodegeneration. There is evidence of loss of excitatory (e.g. cholinergic) enteric neurons and interstitial cells of Cajal, whereas inhibitory (including nitrergic) neurons appear unaffected. Understanding neurodegeneration in the enteric nervous system is key to developing treatments to reverse it. Neurotrophins have been shown to accelerate colonic transit and relieve constipation in the medium term; they are also implicated in maintenance programmes in adult enteric neurons through a role in antioxidant defence. However, their effects in ageing colon require further study. There is evidence that 5-HT(2) and 5-HT(4) mechanisms are involved in development, maintenance and survival of enteric neurons. Further research is needed to understand and potentially reverse enteric neurodegeneration.