Implications of altered gastrointestinal motility in obesity. Obes Surg. 2007;17:1399-1407. [PMID: 18098402 DOI: 10.1007/s11695-007-9221-0]

Pathological Remodeling of the Gut Barrier as a Prodromal Event of High-Fat Diet-Induced Obesity

Intestinal barrier alterations represent a primum movens in obesity and related intestinal dysfunctions. However, whether gut barrier remodeling represents prodromal events in obesity before weight gain, metabolic alterations, and systemic inflammation remains unclear. Herein, we examined morphologic changes in the gut barrier in a mouse model of high-fat diet (HFD) since the earliest phases of diet assumption. C57BL/6J mice were fed with standard diet (SD) or HFD for 1, 2, 4, or 8 weeks. Remodeling of intestinal epithelial barrier, inflammatory infiltrate, and collagen deposition in the colonic wall was assessed by histochemistry and immunofluorescence analysis. Obese mice displayed increased body and epididymal fat weight along with increased plasma resistin, IL-1β, and IL-6 levels after 8 weeks of HFD. Starting from 1 week of HFD, mice displayed (1) a decreased claudin-1 expression in lining epithelial cells, (2) an altered mucus in goblet cells, (3) an increase in proliferating epithelial cells in colonic crypts, (4) eosinophil infiltration along with an increase in vascular P-selectin, and (5) deposition of collagen fibers. HFD intake is associated with morphologic changes in the large bowel at mucosal and submucosal levels. In particular, the main changes include alterations in the mucous layer and intestinal epithelial barrier integrity and activation of mucosal defense-enhanced fibrotic deposition. These changes represent early events occurring before the development of obesity condition that could contribute to compromising the intestinal mucosal barrier and functions, opening the way for systemic dissemination.

Peripheral administration of neuropeptide W inhibits gastric emptying in rats: The role of small diameter afferent fibers and cholecystokinin receptors

Neuropeptide W (NPW), a novel hypothalamic peptide, contributes to the central regulation of food intake and energy balance, and suppresses feeding behavior when administered centrally. The aim of our study was to investigate the role of peripherally administered NPW in the modulation of gastric emptying, and to evaluate the participation of afferent fibers, cholecystokinin (CCK) receptors and gastric smooth muscle contractility in the regulatory effects of NPW on gastric motility. In Sprague-Dawley male rats equipped with gastric fistula, gastric emptying rate of the saline and peptone solutions was measured following subcutaneous administration of NPW (0.1 or 5 μg/kg) preceded by subcutaneous injections of saline, CCK-1 or CCK-2 receptor antagonists. Another group of rats with cannulas were injected subcutaneously with capsaicin for afferent denervation before commencing emptying trials. The effect of NPW on carbachol-induced gastric contractility and the role of CCK receptors in gastric smooth muscle contractility were also assessed in gastric strips. Peripheral injection of NPW delayed gastric emptying rate of both caloric and non-caloric liquid test meals, while administration of CCK-1 or CCK-2 receptor antagonists or denervation of small diameter afferents reversed NPW-induced delay in gastric emptying. Moreover, NPW inhibited antrum contractility in the organ bath. Our results revealed that peripherally administered NPW delayed liquid emptying from the stomach via the involvement of small diameter afferent neurons and CCK receptors, and thereby this regulatory role may contribute to its central regulatory role in controlling food intake and energy balance.

Dietary Supplement, Containing the Dry Extract of Curcumin, Emblica and Cassia, Counteracts Intestinal Inflammation and Enteric Dysmotility Associated with Obesity

Intestinal epithelial barrier (IEB) impairment and enteric inflammation are involved in the onset of obesity and gut-related dysmotility. Dietary supplementation with natural plant extracts represents a useful strategy for the management of body weight gain and systemic inflammation associated with obesity. Here, we evaluate the efficacy of a food supplement containing the dry extract of Curcumin, Emblica and Cassia in counteracting enteric inflammation and motor abnormalities in a mouse model of obesity, induced by a high-fat diet (HFD). Male C57BL/6 mice, fed with standard diet (SD) or HFD, were treated with a natural mixture (Curcumin, Emblica and Cassia). After 8 weeks, body weight, BMI, liver and spleen weight, along with metabolic parameters and colonic motor activity were evaluated. Additionally, plasma LBP, fecal calprotectin, colonic levels of MPO and IL-1β, as well as the expression of occludin, TLR-4, MYD88 and NF-κB were investigated. Plant-based food supplement administration (1) counteracted the increase in body weight, BMI and metabolic parameters, along with a reduction in spleen and liver weight; (2) showed strengthening effects on the IEB integrity; and (3) reduced enteric inflammation and oxidative stress, as well as ameliorated the colonic contractile dysfunctions. Natural mixture administration reduced intestinal inflammation and counteracted the intestinal motor dysfunction associated with obesity.

Eating Frequency in European Children from 1 to 96 Months of Age: Results of the Childhood Obesity Project Study

We aimed to investigate the eating frequency (EF) in children over age, and examined the influence of country, sex, feeding mode and weight status on EF. We used the dietary data of the Childhood Obesity Project, which comprised European children from five countries. Dietary data of 3-days weighed and estimated records were available monthly from 1 to 9 and at 12-, 24-, 36-, 48-, 60-, 72- and 96-months old. Generalized additive mixed effects models were used to estimate EF trajectories with EF as outcome and applying age splines. Additionally, the models were further adjusted for country, feeding mode, sex or weight status. Data from 1244 children were analysed. EF was highest at 1 month with on average 7.3 ± 1.9 feeds per day, and fell to 5.1 ± 1.1 eating occasions at the age 96 months. Night feeding was similarly often than day feeding at 1 month but declined thereafter. Significant differences in EF were observed between countries (p < 0.05), with the highest EF in Poland, and between infant feeding modes, with a higher EF in breastfed than non-breastfed infants (p < 0.05). Sex and body weight were not associated with EF. Despite the importance of EF towards total energy intake, no association with weight status was found.

Distribution of transient receptor potential vanilloid-1 channels in gastrointestinal tract of patients with morbid obesity

BACKGROUND

Transient receptor potential vanilloid-1 (TRPV1), a nonselective cation channel, is activated by capsaicin, a pungent ingredient of hot pepper. Previous studies have suggested a link between obesity and capsaicin-associated pathways, and activation of TRPV1 may provide an alternative approach for obesity treatment. However, data on the TRPV1 distribution in human gastric mucosa are limited, and the degree of TRPV1 distribution in the gastric and duodenal mucosal cells of obese people in comparison with normal-weight individuals is unknown.

AIM

To clarify gastric and duodenal mucosal expression of TRPV1 in humans and compare TRPV1 expression in obese and healthy individuals.

METHODS

Forty-six patients with a body mass index (BMI) of > 40 kg/m² and 20 patients with a BMI between 18-25 kg/m² were included. Simultaneous biopsies from the fundus, antrum, and duodenum tissues were obtained from subjects between the ages of 18 and 65 who underwent esophagogastroduodenoscopy. Age, sex, history of alcohol and cigarette consumption, and past medical history regarding chronic diseases and medications were accessed from patient charts and were analyzed accordingly. Evaluation with anti-TRPV1 antibody was performed separately according to cell types in the fundus, antrum, and duodenum tissues using an immunoreactivity score. Data were analyzed using SPSS 17.0.

RESULTS

TRPV1 expression was higher in the stomach than in the duodenum and was predominantly found in parietal and chief cells of the fundus and mucous and foveolar cells of the antrum. Unlike foveolar cells in the antrum, TRPV1 was relatively low in foveolar cells in the fundus (4.92 ± 0.49 vs 0.48 ± 0.16, P < 0.01, Mann-Whitney U test). Additionally, the mucous cells in the duodenum also had low levels of TRPV1 compared to mucous cells in the antrum (1.33 ± 0.31 vs 2.95 ± 0.46, P < 0.01, Mann-Whitney U test). TRPV1 expression levels of different cell types in the fundus, antrum, and duodenum tissues of the morbidly obese group were similar to those of the control group. Staining with TRPV1 in fundus chief cells and antrum and duodenum mucous cells was higher in patients aged ≥ 45 years than in patients < 45 years (3.03 ± 0.42, 4.37 ± 0.76, 2.28 ± 0.55 vs 1.9 ± 0.46, 1.58 ± 0.44, 0.37 ± 0.18, P = 0.03, P < 0.01, P < 0.01, respectively, Mann-Whitney U test). The mean staining levels of TRPV1 in duodenal mucous cells in patients with diabetes and hypertension were higher than those in patients without diabetes and hypertension (diabetes: 2.11 ± 0.67 vs 1.02 ± 0.34, P = 0.04; hypertension: 2.42 ± 0.75 vs 1.02 ± 0.33, P < 0.01 Mann-Whitney U test).

CONCLUSION

The expression of TRPV1 is unchanged in the gastroduodenal mucosa of morbidly obese patients demonstrating that drugs targeting TRPV1 may be effective in these patients.

Changes in ghrelin, substance P and vasoactive intestinal peptide levels in the gastroduodenal mucosa of patients with morbid obesity

AIMS

The aim of the study was to assess changes in levels of substance P (SP), vasoactive intestinal peptide (VIP) and ghrelin in the gastroduodenal mucosa of obese individuals, which has not been studied before.

METHODS

Forty-six patients with a body mass index (BMI) of >40 kg/m² and 20 patients with a BMI of 18-25 kg/m² were included in the study. VIP and SP levels in the fundus, antrum and duodenal mucosa were measured in freshly frozen tissues using enzyme-linked immunosorbent assay (ELISA). Fasting levels of ghrelin in blood were also measured with ELISA. Tissue levels of ghrelin were assessed by immunohistochemical staining, and immunoreactivity scores were used for ghrelin evaluation in tissues.

RESULTS

Antrum SP levels were higher in the obese group than in the control group. A significant number of obese patients had low VIP levels in the fundus and antrum. Intense ghrelin staining was observed in a limited number of cells in the mucosal area of the gastric fundus that was similar in the control and patient groups. In the antrum and duodenum, ghrelin staining was low in all the samples examined.

CONCLUSION

Here, we found that SP levels are increased, while VIP levels are decreased in the antrum of morbidly obese individuals. Previous studies show that SP increases gastroduodenal motility, that VIP slows it down, and that the gastric emptying rate is higher in obese individuals, preventing negative feedback mechanisms upon food intake. Therefore, increases in SP and decreases in VIP levels in the antrum may contribute to obesity by accelerating gastric emptying.

NLRP3 at the crossroads between immune/inflammatory responses and enteric neuroplastic remodelling in a mouse model of diet-induced obesity

BACKGROUND AND PURPOSE

Enteric neurogenic/inflammation contributes to bowel dysmotility in obesity. We examined the role of NLRP3 in colonic neuromuscular dysfunctions in mice with high-fat diet (HFD)-induced obesity.

EXPERIMENTAL APPROACH

Wild-type C57BL/6J and NLRP3-KO (Nlrp3^-/- ) mice were fed with HFD or standard diet for 8 weeks. The activation of inflammasome pathways in colonic tissues from obese mice was assessed. The role of NLRP3 in in vivo colonic transit and in vitro tachykininergic contractions and substance P distribution was evaluated. The effect of substance P on NLRP3 signalling was tested in cultured cells.

KEY RESULTS

HFD mice displayed increased body and epididymal fat weight, cholesterol levels, plasma resistin levels and plasma and colonic IL-1β levels, colonic inflammasome adaptor protein apoptosis-associated speck-like protein containing caspase-recruitment domain (ASC) and caspase-1 mRNA expression and ASC immunopositivity in macrophages. Colonic tachykininergic contractions were enhanced in HFD mice. HFD NLRP3^-/- mice developed lower increase in body and epididymal fat weight, cholesterol levels, systemic and bowel inflammation. In HFD Nlrp3^-/- mice, the functional alterations of tachykinergic pathways and faecal output were normalized. In THP-1 cells, substance P promoted IL-1β release. This effect was inhibited upon incubation with caspase-1 inhibitor or NK₁ antagonist and not observed in ASC^-/- cells.

CONCLUSION AND IMPLICATIONS

In obesity, NLRP3 regulates an interplay between the shaping of enteric immune/inflammatory responses and the activation of substance P/NK₁ pathways underlying the onset of colonic dysmotility. Identifying NLRP3 as a therapeutic target for the treatment of bowel symptoms related to obesity.

Gastric motor dysfunction coincides with the onset of obesity in rats fed with high-fat diet

Exposure to a high-fat diet (HFD) has been reported to impair central autonomic and enteric neurocircuitries, however, the relevant mechanisms and their time course are inadequately clarified. This study aimed to investigate the effects of HFD consumption through the period of adolescence on gastric motor functions in adulthood. Male Sprague-Dawley rats consumed a regular diet or HFD (60% kcal by fat) from 4 to 12 weeks of age. Body weight and food intake were monitored weekly. In adult rats, gastric emptying (GE) was measured. Additionally, using in-vitro organ bath, contractile and relaxant responses of antral and fundic strips were assessed with bethanechol and sodium nitroprusside (SNP), respectively. The expressions of choline acetyltransferase (ChAT), neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP) were detected by immunofluorescence, whereas, the number of myenteric neurons were evaluated by staining with cuprolinic blue and enteric neuronal marker PGP 9.5. In adulthood, the HFD did not alter food intake, while significantly increasing the body weight. In HFD-fed adult rats, increased visceral fat mass was accompanied by delayed GE. Moreover, bethanechol- and SNP-induced responses were attenuated in antral and fundic tissues. HFD remarkably decreased the number of myenteric neurons and NOS immunoreactivity both in fundus and antrum. HFD remarkably decreased ChAT expression, while increasing the immunoreactivity for VIP in antrum. In conclusion, consumption of HFD between early adolescence and adulthood results in obesity and impairment of gastric motor functions. Particularly, HFD-induced gastric dysmotility appears to be predominantly dependent on the modifications in the non-adrenergic non-cholinergic inhibitory neurotransmission.

Effects of Long-Term High-Fat Diet and Its Reversal on Lipids and Lipoproteins Composition in Thoracic Duct Lymph in Pigs

Background

This study was carried out to evaluate the effects of a long-term high-fat diet on lipids and lipoproteins composition in thoracic duct lymph in pigs.

Material/Methods

We examined lymph taken from the thoracic duct from 24 female white sharp-ear pigs, divided into 3 experimental groups fed different diets for 12 months: (a) the control group, fed the standard balanced diet; (b) the HFD group, fed an unbalanced, high-fat diet, and (c) the reversal diet group (RD), fed an unbalanced, high-fat diet for 9 months and then a standard balanced diet for 3 months.

Results

Lymph analysis after 12 months of fixed diets revealed significantly higher concentration of proteins in the HFD group in comparison to the control and RD groups. Examination of lymph lipoproteins fractions showed that the high-fat diet in the HFD group in comparison to control group caused an increase in cholesterol, phospholipids, and proteins content within HDL and chylomicrons. There were also more proteins within HDL in the HFD group in comparison to the RD group and more triglycerides within chylomicrons in the HFD group in comparison to the control group.

Conclusion

A long-term high-fat diet resulted in changed structure of HDL and chylomicrons in the thoracic duct lymph. Alterations in HDL composition suggest that a high-fat diet enhances reverses cholesterol transport. Changes in chylomicrons structure show the adaptation to more intense transport of dietary fat from the intestine to the liver under the influence of a high-fat diet. Reversal to a standard balanced diet had the opposite effects.

Adipocytes-released Peptides Involved in the Control of Gastrointestinal Motility

The present review focuses on adipocytes-released peptides known to be involved in the control of gastrointestinal motility, acting both centrally and peripherally. Thus, four peptides have been taken into account: leptin, adiponectin, nesfatin-1, and apelin. The discussion of the related physiological or pathophysiological roles, based on the most recent findings, is intended to underlie the close interactions among adipose tissue, central nervous system, and gastrointestinal tract. The better understanding of this complex network, as gastrointestinal motor responses represent peripheral signals involved in the regulation of food intake through the gut-brain axis, may also furnish a cue for the development of either novel therapeutic approaches in the treatment of obesity and eating disorders or potential diagnostic tools.

High-Fat Diet During the Perinatal Period Induces Loss of Myenteric Nitrergic Neurons and Increases Enteric Glial Density, Prior to the Development of Obesity

Diet-induced obesity induces peripheral inflammation accompanied by a loss of myenteric neurons. Few studies, however, have investigated the effects of a high-fat diet (HFD) on either the development of myenteric neurons or prior to the occurrence of obesity. The present study assessed the effects of maternal HFD on the density and neurochemical phenotype of myenteric ganglia in the upper gastrointestinal tract. Sprague-Dawley rats were fed either a control or HFD (14% or 60% kcal from fat, respectively) from embryonic day 13; the fundus, corpus and duodenum were fixed thereafter at postnatal 2, 4, 6 and 12 weeks of age for subsequent immunohistochemical studies. While myenteric ganglion size did not differ throughout the study, HFD exposure decreased the number of nitrergic neurons by 6 weeks of age in all regions. This decrease was accompanied by a loss of PGP-immunoreactive neurons, suggesting a decline in myenteric neuronal number. HFD also increased myenteric plexus glial cell density in all regions by 4 weeks of age. These changes occurred in the absence of an increase in serum or gastric inflammatory markers. The present study suggests that exposure to a HFD during the perinatal time period results in glial proliferation and loss of inhibitory nitrergic neurons prior to the onset of obesity, suggesting that dietary alterations may affect gastrointestinal functions independently of increased adiposity or glycemic dysregulation.

Energy intake, gastrointestinal transit, and gut hormone release in response to oral triglycerides and fatty acids in men with and without severe obesity

Dietary fat, and particularly fatty acids (FAs) from hydrolyzed triglycerides (TGs), reduces appetite, whereas paradoxically, a high-fat diet leads to excess calorie intake. We therefore hypothesized that the appetite-regulating effects of FAs are perturbed in obesity. Ten men with severe obesity [median body mass index (BMI) of 51.0 kg/m² (range of 47.9-69.0)] and 10 men without obesity [BMI of 24.6 kg/m² (range of 21.7-26.8)] were recruited for a double-blind randomized crossover study. On two occasions, participants were given isocaloric (2,660 kJ) and isovolemic (80 ml) loads of either oleic acid (long-chain FA) or olive oil (TG) containing radiolabeled lipid and water markers. Postload scintigraphy, blood sampling, and assessment of appetite were performed for 10 h, after which an ad libitum meal was served. Compared with olive oil, oleic acid slowed gastric mean emptying time (GMET) for lipids ( P < 0.001), accelerated orocoecal transit time (OCTT; P = 0.005), increased postload cholecystokinin section ( P < 0.001), and suppressed ad libitum energy intake ( P = 0.028) in men with severe obesity, and similar effects were seen in the nonobese group (no group × lipid interactions). However, independent of lipid loads, GMET and OCTT were slower (GMET_lipid P = 0.046; GMET_water P = 0.003; OCTT P = 0.001), and basal and postload secretion of glucagon-like peptide-1 (GLP-1) was attenuated ( P = 0.045 and P = 0.048, respectively) in men with severe obesity compared with men without obesity. We conclude that the more potent appetite-regulating effects of oleic acid versus olive oil are unimpaired in men with severe obesity. However, regardless of lipid formulations, severe obesity is associated with slowed gastrointestinal transit and attenuated GLP-1 secretion. NEW & NOTEWORTHY Orally ingested fatty acids more efficiently reduce appetite and energy intake than triglycerides also in men with severe obesity. Men with severe obesity have delayed gastrointestinal transit and attenuated early gut hormone responses after an oral lipid load compared with men without obesity.

Role of astroglia in diet-induced central neuroplasticity

Obesity, characterized by increased adiposity that develops when energy intake outweighs expenditure, is rapidly becoming a serious health crisis that affects millions of people worldwide and is associated with severe comorbid disorders including hypertension, cardiovascular disease, and type II diabetes. Obesity is also associated with the dysregulation of central neurocircuits involved in the control of autonomic, metabolic, and cognitive functions. Systemic inflammation associated with diet-induced obesity (DIO) has been proposed to be responsible for the development of these comorbidities as well as the dysregulation of central neurocircuits. A growing body of evidence suggests, however, that exposure to a high-fat diet (HFD) may cause neuroinflammation and astroglial activation even before systemic inflammation develops, which may be sufficient to cause dysregulation of central neurocircuits involved in energy homeostasis before the development of obesity. The purpose of this review is to summarize the current literature exploring astroglial-dependent modulation of central circuits following exposure to HFD and DIO, including not only dysregulation of neurocircuits involved in energy homeostasis and feeding behavior, but also the dysregulation of learning, memory, mood, and reward pathways.

Gastrointestinal Transit Time, Glucose Homeostasis and Metabolic Health: Modulation by Dietary Fibers

Gastrointestinal transit time may be an important determinant of glucose homeostasis and metabolic health through effects on nutrient absorption and microbial composition, among other mechanisms. Modulation of gastrointestinal transit may be one of the mechanisms underlying the beneficial health effects of dietary fibers. These effects include improved glucose homeostasis and a reduced risk of developing metabolic diseases such as obesity and type 2 diabetes mellitus. In this review, we first discuss the regulation of gastric emptying rate, small intestinal transit and colonic transit as well as their relation to glucose homeostasis and metabolic health. Subsequently, we briefly address the reported health effects of different dietary fibers and discuss to what extent the fiber-induced health benefits may be mediated through modulation of gastrointestinal transit.

Comparative assessment of gastric emptying in obese patients before and after laparoscopic sleeve gastrectomy using radionuclide scintigraphy

Radionuclide scintigraphy provides a standard physiologic evaluation of gastric emptying (GE) after laparoscopic sleeve gastrectomy (LSG). This operation can be associated with motor gastric dysfunction and abnormal GE. The aim of this study was to evaluate the short-term effect of LSG on GE quantitative indices for liquids and solids compared with preoperative results. Forty obese patients were divided into two equal groups, the liquid and solid groups. Tc-sulfur colloid GE scintigraphy was performed on all patients submitted to LSG before and after surgery (1-4 weeks for liquids and 4-6 weeks for solids). The quantitative indices included half emptying time (T1/2) and percentage gastric retention at 15, 30, and 60 min for liquids and at 30, 60, 90, and 120 min for solids. A modified technique was used to label a boiled egg in order to be tolerated by the patients. T1/2 was significantly enhanced after LSG compared with baseline (25.3±4.4 vs. 11.8±3.0 min for liquids and 74.9±7.1 vs. 28.4±8.3 min for solids, respectively, P<0.001). The percentage of gastric retention in operated patients was significantly less than that at baseline for liquids at 15, 30, and 60 min (33.9±5.6, 17.7±3.9, and 7.5±2.8% vs. 69.4±10.5, 55.6±14.95, and 26.1±4.7%, respectively, P<0.001), as well as for solids at 30, 60, 90, and 120 min (42.0±11.1, 20.8±6.1, 11.0±5.9, and 3.8±2.7% vs. 79.9±8.7, 67.4±12.2, 37.0±10.9%, and 13.8±4.4%, respectively, P<0.001). The significant acceleration of GE of liquids and solids after LSG may have contributed to weight loss in the immediate postoperative period (4-6 weeks). It remains to be determined whether the weight loss will continue beyond that period.

Obese children and adolescents need increased gastric volumes in order to perceive satiety

OBJECTIVE

In order to develop effective weight management strategies, it is important to identify factors that influence energy intake. Portion size has been discussed as one such factor. To date, most studies focusing on the relationship between portion size, energy intake, and weight have analyzed questionnaire data and 24-h records. In this study, we assessed the onset of satiety using the water-load test in normal-weight and obese children and adolescents.

METHODS

60 obese and 27 normal-weight children and adolescents aged between 9 and 17 years participated in the water load test which involved drinking water for 3 min or until feeling full. The amount of water consumed was recorded.

RESULTS

Obese children and adolescents drank 20% more water until the onset of satiety when compared with normal-weight participants (478 ± 222 ml vs. 385 ± 115 ml, P < 0.05).

CONCLUSIONS

Obese children and adolescents need to ingest greater volumes to feel full which may predispose toward the consumption of larger portion sizes. This may easily lead to overeating if predominantly energy-dense foods are consumed. A reduction in energy-dense foods in the diet of obese children and adolescents appears to be a necessary strategy for managing body weight.

Properties of myenteric neurones and mucosal functions in the distal colon of diet-induced obese mice

Colonic transit and mucosal integrity are believed to be impaired in obesity. However, a comprehensive assessment of altered colonic functions, inflammatory changes and neuronal signalling of obese animals is missing. In mice, we studied the impact of diet-induced obesity (DIO) on: (i) in vivo colonic transit; (ii) signalling in the myenteric plexus by recording responses to nicotine and 2-methyl-5-hydroxytryptamine (2-methyl-5-HT), together with the expression of tryptophan hydroxylase (TPH) 1 and 2, serotonin reuptake transporter, choline acetyltransferase and the paired box gene 4; and (iii) expression of proinflammatory cytokines, epithelial permeability and density of macrophages, mast cells and enterochromaffin cells. Compared with controls, colon transit and neuronal sensitivity to nicotine and 2-methyl-5-HT were enhanced in DIO mice fed for 12 weeks. This was associated with increased tissue acetylcholine and 5-hydroxytryptamine (5-HT) content, and increased expression of TPH1 and TPH2. In DIO mice, upregulation of proinflammatory cytokines was found in fat tissue, but not in the gut wall. Accordingly, mucosal permeability or integrity was unaltered without signs of immune cell infiltration in the gut wall. Body weight showed positive correlations with adipocyte markers, tissue levels of 5-HT and acetylcholine, and the degree of neuronal sensitization. DIO mice fed for 4 weeks showed no neuronal sensitization, had no signs of gut wall inflammation and showed a smaller increase in leptin, interleukin-6 and monocyte chemoattractant protein 1 expression in fat tissue. DIO is associated with faster colonic transit and impacts on acetylcholine and 5-HT metabolism with enhanced responsiveness of enteric neurones to both mediators after 12 weeks of feeding. Our study demonstrates neuronal plasticity in DIO prior to the development of a pathological histology or abnormal mucosal functions. This questions the common assumption that increased mucosal inflammation and permeability initiate functional disorders in obesity.

Gastric electrical stimulation for the treatment of obesity: from entrainment to bezoars-a functional review

GROWING WORLDWIDE OBESITY EPIDEMIC HAS PROMPTED THE DEVELOPMENT OF TWO MAIN TREATMENT STREAMS: (a) conservative approaches and (b) invasive techniques. However, only invasive surgical methods have delivered significant and sustainable benefits. Therefore, contemporary research exploration has focused on the development of minimally invasive gastric manipulation methods featuring a safe but reliable and long-term sustainable weight loss effect similar to the one delivered by bariatric surgeries. This antiobesity approach is based on placing external devices in the stomach ranging from electrodes for gastric electrical stimulation to temporary intraluminal bezoars for gastric volume displacement for a predetermined amount of time. The present paper examines the evolution of these techniques from invasively implantable units to completely noninvasive patient-controllable implements, from a functional, rather than from the traditional, parametric point of view. Comparative discussion over the available pilot and clinical studies related to gastric electrical stimulation outlines the promises and the fallacies of this concept as a reliable alternative anti-obesity strategy.

Upper gastrointestinal symptoms in obese patients and their outcomes after bariatric surgery

Obesity is considered an important risk factor for the development of gastrointestinal (GI) disorders, likely through alterations of GI motility. Even though gastroesophageal reflux disease is the condition mainly studied at present, the prevalence of other upper GI symptoms is also augmented in obese patients. Owing to their chronic trend, these disorders have a bearing on public spending and their correct diagnosis would avoid unnecessary cost-consuming investigations. Furthermore, bariatric surgery dramatically changes GI anatomy and physiology, influencing GI symptom outcomes. The aim of this review is to categorize the available results in a pathophysiological framework in an attempt to set up the correct clinical GI management of obese patients before and after bariatric surgery. This would be helpful in tentatively reducing their considerable economic burden on public health services.

Serotonin availability in rat colon is reduced during a Western diet model of obesity

Constipation and slowed transit are associated with diet-induced obesity, although the mechanisms by which this occurs are unclear. Enterochromaffin (EC) cells within the intestinal epithelium respond to mechanical stimulation with the release of serotonin [5-hydroxytryptamine (5-HT)], which promotes transit. Thus our aim was to characterize 5-HT availability in the rat colon of a physiologically relevant model of diet-induced obesity. EC cell numbers were determined immunohistochemically in chow-fed (CF) and Western diet-fed (WD) rats, while electrochemical methods were used to measure mechanically evoked (peak) and steady-state (SS) 5-HT levels. Fluoxetine was used to block the 5-HT reuptake transporter (SERT), and the levels of mRNA for tryptophan hydroxylase 1 and SERT were determined by quantitative PCR, and SERT protein was determined by Western blot. In WD rats, there was a significant decrease in the total number of EC cells per crypt (0.86 ± 0.06 and 0.71 ± 0.05 in CF and WD, respectively), which was supported by a reduction in the levels of 5-HT in WD rats (2.9 ± 1.0 and 10.5 ± 2.6 μM at SS and peak, respectively) compared with CF rats (7.3 ± 0.4 and 18.4 ± 3.4 μM at SS and peak, respectively). SERT-dependent uptake of 5-HT was unchanged, which was supported by a lack of change in SERT protein levels. In WD rats, there was no change in tryptophan hydroxylase 1 mRNA but an increase in SERT mRNA. In conclusion, our data show that foods typical of a WD are associated with decreased 5-HT availability in rat colon. Decreased 5-HT availability is driven primarily by a reduction in the numbers and/or 5-HT content of EC cells, which are likely to be associated with decreased intestinal motility in vivo.

Gastric stimulation for weight loss

The prevalence of obesity is growing to epidemic proportions, and there is clearly a need for minimally invasive therapies with few adverse effects that allow for sustained weight loss. Behavior and lifestyle therapy are safe treatments for obesity in the short term, but the durability of the weight loss is limited. Although promising obesity drugs are in development, the currently available drugs lack efficacy or have unacceptable side effects. Surgery leads to long-term weight loss, but it is associated with morbidity and mortality. Gastric electrical stimulation (GES) has received increasing attention as a potential tool for treating obesity and gastrointestinal dysmotility disorders. GES is a promising, minimally invasive, safe, and effective method for treating obesity. External gastric pacing is aimed at alteration of the motility of the gastrointestinal tract in a way that will alter absorption due to alteration of transit time. In addition, data from animal models and preliminary data from human trials suggest a role for the gut-brain axis in the mechanism of GES. This may involve alteration of secretion of hormones associated with hunger or satiety. Patient selection for gastric stimulation therapy seems to be an important determinant of the treatment’s outcome. Here, we review the current status, potential mechanisms of action, and possible future applications of gastric stimulation for obesity.

Prebiotic fibres dose-dependently increase satiety hormones and alter Bacteroidetes and Firmicutes in lean and obese JCR:LA-cp rats

There is a growing interest in modulating gut microbiota with diet in the context of obesity. The purpose of the present study was to evaluate the dose-dependent effects of prebiotics (inulin and oligofructose) on gut satiety hormones, energy expenditure, gastric emptying and gut microbiota. Male lean and obese JCR:LA-cp rats were randomised to either of the following: lean 0 % fibre (LC), lean 10 % fibre (LF), lean 20 % fibre (LHF), obese 0 % fibre (OC), obese 10 % fibre (OF) or obese 20 % fibre (OHF). Body composition, gastric emptying, energy expenditure, plasma satiety hormone concentrations and gut microbiota (using quantitative PCR) were measured. Caecal proglucagon and peptide YY mRNA levels were up-regulated 2-fold in the LF, OF and OHF groups and 3-fold in the LHF group. Ghrelin O-acyltransferase mRNA levels were higher in obese v. lean rats and decreased in the OHF group. Plasma ghrelin response was attenuated in the LHF group. Microbial species measured in the Bacteroidetes division decreased, whereas those in the Firmicutes increased in obese v. lean rats and improved with prebiotic intake. Bifidobacterium and Lactobacillus increased in the OHF v. OC group. Bacteroides and total bacteria negatively correlated with percentage of body fat and body weight. Enterobacteriaceae increased in conjunction with glucose area under the curve (AUC) and glucagon-like peptide-1 AUC. Bacteroides and total bacteria correlated positively with ghrelin AUC yet negatively with insulin AUC and energy intake (P < 0·05). Several of the mechanisms through which prebiotics act (food intake, satiety hormones and alterations in gut microbiota) are regulated in a dose-dependent manner. The combined effects of prebiotics may have therapeutic potential for obesity.

Leptin excites enteric neurons of guinea-pig submucous and myenteric plexus

BACKGROUND

Leptin, one of the most prominent mediators released from adipocytes, influences neuronal activity in the central nervous system. The enteric nervous system (ENS) expresses leptin receptors but consequence of activation of these receptors on enteric neuron activity has not been systematically studied. An adipocyte-ENS axis is suggested by close apposition between enteric nerves and adipocytes. The aim of this study was to investigate the effects of leptin on guinea-pig submucous and myenteric neurons.

METHODS

Using voltage sensitive dye imaging, we recorded neural responses to application of leptin (0.0625 nmol L(-1)) in myenteric and submucous neurons, nicotine (10 μmol L(-1)) served as a reference for neuronal excitation. Mucosal ion secretion and muscle activity were measured in vitro with Ussing and organ bath techniques, respectively.

KEY RESULTS

Leptin induced spike discharge in 13.6% of submucous neurons and in 8.2% of myenteric neurons (1.1 ± 0.9 and 1.2 ± 1.0 Hz, respectively). Although there was an overlap of nicotine and leptin responses, 38.5% of submucous and 25% of myenteric neurons activated by leptin did not respond to nicotine. Leptin did not inhibit ongoing spike discharge or fast excitatory postsynaptic potentials. Leptin (0.0625 nmol L(-1)) did not affect mucosal secretion or muscle activity suggesting a subtle modulatory action of leptin at the level of the ENS.

CONCLUSIONS & INFERENCES

Leptin activates submucous and myenteric neurons indicating relevance for adipocyte-ENS signaling. These results set the basis for further studies to reveal the functional correlate of the neural action of leptin in the ENS.

Fatty acid detection during food consumption and digestion: Associations with ingestive behavior and obesity

The inability of humans to adequately regulate fat consumption is a salient contributor to the development of obesity. The macronutrients, fat, protein and carbohydrate, within foods are detected at various stages of consumption, during which their digestive products, fatty acids, amino acids and sugars, interact with chemosensory cells within the oral epithelium (taste receptor cells) and gastrointestinal (GI) tract (enteroendocrine cells). This chemoreception initiates functional responses, including taste perception, peptide secretion and alterations in GI motility, that play an important role in liking of food, appetite regulation and satiety. This review will summarize the available evidence relating to the oral and GI regulation of fat intake and how chemoreception at both locations is associated with digestive behavior, satiety and weight regulation.

Gastrointestinal system and obesity

Several significant changes occur in the gastrointestinal system with obesity that can effect management in critical illness. This population is at risk for gastroesophageal reflux disease (GERD), abdominal compartment syndrome, nonalcoholic fatty liver disease (NAFLD), and an increased incidence of cholelithiasis. It is important for critical care providers to be aware of these potential complicating factors.

A Western diet increases serotonin availability in rat small intestine

Diet-induced obesity is associated with changes in gastrointestinal function and induction of a mild inflammatory state. Serotonin (5-HT) containing enterochromaffin (EC) cells within the intestine respond to nutrients and are altered by inflammation. Thus, our aim was to characterize the uptake and release of 5-HT from EC cells of the rat ileum in a physiologically relevant model of diet-induced obesity. In chow-fed (CF) and Western diet-fed (WD) rats electrochemical methods were used to measure compression evoked (peak) and steady state (SS) 5-HT levels with fluoxetine used to block the serotonin reuptake transporter (SERT). The levels of mRNA for tryptophan hydroxylase 1 (TPH1) and SERT were determined by quantitative PCR, while EC cell numbers were determined immunohistochemically. In WD rats, the levels of 5-HT were significantly increased (SS: 19.2 ± 3.7 μm; peak: 73.5 ± 14.1 μm) compared with CF rats (SS: 12.3 ± 1.8 μm; peak: 32.2 ± 7.2 μm), while SERT-dependent uptake of 5-HT was reduced (peak WD: 108% of control versus peak CF: 212% control). In WD rats, there was a significant increase in TPH1 mRNA, a decrease in SERT mRNA and protein, and an increase in EC cells. In conclusion, our data show that foods typical of a Western diet are associated with an increased 5-HT availability in the rat ileum. Increased 5-HT availability is driven by the up-regulation of 5-HT synthesis genes, decreased re-uptake of 5-HT, and increased numbers and/or 5-HT content of EC cells which are likely to cause altered intestinal motility and sensation in vivo.

The effect of eating frequency on appetite control and food intake: brief synopsis of controlled feeding studies

Increased eating frequency is postulated to increase metabolism, reduce hunger, improve glucose and insulin control, and reduce body weight, making it an enticing dietary strategy for weight loss and/or the maintenance of a healthy body weight. Because past research has primarily focused on the effects of eating frequency on changes in energy expenditure and body weight, limited data exist surrounding the impact of eating frequency on appetite control and energy intake. We provide a brief review of the controlled-feeding studies that primarily targeted the appetitive, hormonal, and food intake responses potentially altered with eating frequency. The 3 meal/d pattern served as the reference for defining increased or reduced eating frequency. In general, increased eating frequency led to lower peaks (P < 0.05) in perceived appetite, satiety, glucose, insulin, ghrelin, and PYY responses compared with reduced eating frequency. However, when examining these responses over the course of the day (i.e. using area under the curve assessments), no differences in any of these outcomes were observed. The rate of gastric emptying also appears to be unaltered with increased eating frequency. Subsequent food intake was examined in several studies with conflicting results. Regarding the effect of reduced eating frequency, several studies indicate significant increases in perceived appetite and reductions in perceived satiety when 1 or 2 meals were eliminated from the daily diet. Taken together, these findings suggest that increased eating frequency (>3 eating occasions/d) has minimal, if any, impact on appetite control and food intake, whereas reduced eating frequency(<3 eating occasions/d) negatively effects appetite control.

Effects of protein quality on appetite and energy metabolism in normal weight subjects

OBJECTIVE

The purpose of this study was to compare the effects of consumption of different protein sources on food intake and energy expenditure in normal weight subjects.

SUBJECTS AND METHODS

Breakfast preparations (casein, soy protein, whey protein or control) were ingested during seven consecutive days. Appetite, food intake, and energy expenditure were assessed.

RESULTS

Casein consumption led to a lower energy intake than whey protein. There was lower energy intake on day 7 than on day 1 of the casein session. Soy protein preparations resulted in higher diet induced thermogenesis (DIT) than in control preparations. The respiratory quotient (RQ) obtained in the whey protein session was lower than the control and soy protein sessions.

CONCLUSION

These results suggest that the consumption of different protein types leads to distinct effects on satiety (casein), DIT (soy protein), and/or RQ (whey protein).

Prevalence and risk factors for gastroesophageal reflux disease in an impoverished minority population

BACKGROUND AND AIMS: An epidemiological link between an increased body mass index and complaints of typical heartburn symptoms has been identified. It appears that increasing waist circumference, rather than overall weight is most important. Studies to date have not included minority, impoverished communities. Our aim was to determine the impact of obesity on the prevalence of reflux disease in an impoverished community while controlling for known confounders. METHODS: DESIGN Cross-sectional survey delivered by in-home interviews, convenience sampling, and targeted mailing. Data queried include demographics, medical history, lifestyle habits, and symptoms of reflux disease. Height, weight, hip and waist circumference measured in participating subjects. PARTICIPANTS: 503 subjects living in the zip code immediately surrounding Temple University Hospital. Included only adults living in the hospital's zip code for at least 3 years. RESULTS: The highest quartile of waist circumference (≥42 in.) demonstrated a strong association with GERD (AOR = 2.15; 95% CI 1.18-3.90). Smoking increased the odds by 1.72 (95% CI 1.13-2.62). There was no relationship between body mass index, waist-hip ratio, or diet and reflux classification. CONCLUSIONS: Increasing waist circumference, but not overall body mass index or waist-hip ratio, and smoking are risk factors for prevalent GERD. No association between reflux disease and lifestyle choices such as coffee drinking and fast food dining were found. LIMITATIONS: Potential for recall bias and disease misclassification. Possible methodological errors in self-measurement of waist and hip circumference.

Scintigraphic evaluation of gastric emptying in obese patients submitted to sleeve gastrectomy compared to normal subjects

BACKGROUND

Sleeve gastrectomy (SG) has been accepted as an option for surgical treatment for obesity. This operation could be associated with motor gastric dysfunction and abnormal gastric emptying. The purpose of this prospective study is to present the results of gastric emptying to liquids and solids using scintigraphy in patients who underwent SG compared to normal subjects.

METHODS

Twenty obese patients were submitted to laparoscopic SG and were compared to 18 normal subjects. Gastric emptying of liquids and solids was measured by scintigraphic technique. Results were expressed as half time of gastric emptying and the percentage of retention at 20, 30, and 60 min for liquids and at 60, 90, and 120 min for solids.

RESULTS

In the group of operated patients, 70% of them (n = 14) presented accelerated emptying for liquids and 75% (n = 15) for solids compared to 22.2% and 27.7%, respectively, in the control group. The half time of gastric emptying (T (1/2)) in patients submitted to SG both for liquids and solids were significantly more accelerated compared to the control group (34.9 +/- 24.6 vs 13.6 +/- 11.9 min for liquids and 78 +/- 15.01 vs 38.3 +/- 18.77 min for solids; p < 0.01). The gastric emptying for liquids expressed as the percentage of retention at 20, 30, and 60 min was 30.0 +/- 0.25%, 15.4 +/- 0.18%, and 5.7 +/- 0.10%, respectively, in operated patients, significantly less than the control subjects (p < 0.001). For solids, the percentage of retention at 60, 90, and 120 min was 56 +/- 28%, 34 +/- 22%, and 12 +/- 8%, respectively, for controls, while it was 25.3 +/- 0.20%, 9 +/- 0.12%, and 3 +/- 0.05%, respectively, in operated patients (p < 001).

CONCLUSIONS

Gastric emptying after SG is accelerated either for liquids as well as for solids in the majority of patients. These results could be taken in consideration for the dietary indications after surgery and could play a significant role in the definitive results during the late follow-up.

Conference on "Multidisciplinary approaches to nutritional problems". Postgraduate Symposium. The role of fat in gastric emptying and satiety: acute and chronic effects

Dietary fat is an important factor in the aetiology of obesity and the metabolic syndrome. It has been widely debated whether gastric emptying (GE) is altered in obesity. GE times have been reported as both longer and shorter in obese individuals compared with matched lean individuals. However, the general consensus is that GE is accelerated and satiety is lower in obesity. Research has implicated a high-fat (HF) diet in these findings. A single HF meal has a longer GE time than a low-fat meal and can even delay GE of the subsequent meal. However, an HF diet has shown different effects. Feeding a HF diet adapts gastrointestinal function to reduce GE times in comparison with a low-fat diet. Increased GE may lead to decreased satiety and faster onset of subsequent eating episodes. Further results have suggested that consuming an HF diet for 14 d increases the GE rate of HF food but not low-fat food. Consuming HF diets for 2 weeks has also been shown to increase food intake. Decreased satiation following an HF diet may cause increased food intake and a positive energy balance, potentially resulting in a gradual increase in adiposity. Recent results have suggested that gastrointestinal transit is accelerated following only 3 d on a HF diet. The variable GE times reported in obesity may be associated with interactions between the HF diet and obesity and not simply the obese state.