Leptin and energy balance: exploring Leptin's role in the regulation of energy intake and energy expenditure.

Leptin is a tonic appetite-regulating hormone, which is integral for the long-term regulation of energy balance. The current evidence suggests that the typical orexigenic or anorexigenic response of many of these appetite-regulating hormones, most notably ghrelin and cholecystokinin (CCK), require leptin to function whereas glucagon-like peptide-1 (GLP-1) is required for leptin to function, and these responses are altered when leptin injection or gene therapy is administered in combination with these same hormones or respective agonists. The appetite-regulatory pathway is complex, thus peptide tyrosine tyrosine (PYY), brain-derived neurotrophic factor (BDNF), orexin-A (OXA), and amylin also maintain ties to leptin, however these are less well understood. While reviews to date have focused on the existing relationships between leptin and the various neuropeptide modulators of appetite within the central nervous system (CNS) or it's role in thermogenesis, no review paper has synthesised the information regarding the interactions between appetite-regulating hormones and how leptin as a chronic regulator of energy balance can influence the acute appetite-regulatory response. Current evidence suggests that potential relationships exist between leptin and the circulating peripheral appetite hormones ghrelin, GLP-1, CCK, OXA and amylin to exhibit either synergistic or opposing effects on appetite inhibition. Though more research is warranted, leptin appears to be integral in both energy intake and energy expenditure. More specifically, functional leptin receptors appear to play an essential role in these processes.

The role of gut microbiota in anorexia induced by T-2 toxin.

T-2 toxin is one of trichothecene mycotoxins, which can impair appetite and decrease food intake. However, the specific mechanisms for T-2 toxin-induced anorexia are not fully clarified. Multiple research results had shown that gut microbiota have a significant effect on appetite regulation. Hence, this study purposed to explore the potential interactions of the gut microbiota and appetite regulate factors in anorexia induced by T-2 toxin. The study divided the mice into control group (CG, 0 mg/kg BW T-2 toxin) and T-2 toxin-treated group (TG, 1 mg/kg BW T-2 toxin), which oral gavage for 4 weeks, to construct a subacute T-2 toxin poisoning mouse model. This data proved that T-2 toxin was able to induce an anorexia in mice by increased the contents of gastrointestinal hormones (CCK, GIP, GLP-1 and PYY), neurotransmitters (5-HT and SP), as well as pro-inflammatory cytokines (IL-1ß, IL-6 and TNF-α) in serum of mice. T-2 toxin disturbed the composition of gut microbiota, especially, Faecalibaculum and Allobaculum, which was positively correlated with CCK, GLP-1, 5-HT, IL-1ß, IL-6 and TNF-α, which played a certain role in regulating host appetite. In conclusion, gut microbiota changes (especially an increase in the abundance of Faecalibaculum and Allobaculum) promote the upregulation of gastrointestinal hormones, neurotransmitters, and pro-inflammatory cytokines, which may be a potential mechanism of T-2 toxin-induced anorexia.

Effects of electroacupuncture combined with acupoint catgut embedding on gastrointestinal motility and gastrointestinal hormones in rats with functional dyspepsia.

Electroacupuncture (EA) or acupoint catgut embedding (ACE) plays a therapeutic role in functional dyspepsia (FD). Herein, we aimed to elucidate the influences of EA combined with ACE on gastrointestinal motility and gastrointestinal hormones in rats with FD. Sprague-Dawley rats were randomized into the control group, model group, EA group, ACE group, and EA + ACE group (n = 10). Except for the control group, the rats in all groups were modeled by combining neonatal iodoacetamide gastrogavage and modified tail-clamping stimulation. The rats were treated with different treatments according to their groups. The rats were observed for changes in general behavior, body weight, food intake, and paw mechanical pain threshold. Gastric emptying rate (GER) and intestinal propulsive ratio (IPR) were measured in each group, and serum gastrointestinal hormone (motilin [MTL], leptin, gastrin [GAS], vasoactive intestinal peptide [VIP], calcitonin gene-related peptide [CGRP], and somatostatin [SS]) levels, oxidative stress factors (superoxide dismutase [SOD] and malondialdehyde [MDA]) and 5-hydroxytryptamine (5-HT) levels were also measured. Decreased mean body weight, paw mechanical pain thresholds, food intake, and GER and IPR were found in rats of the model group in comparison to the control group. Serum MTL, GAS, SS, and SOD levels were reduced, and serum leptin, VIP, CGRP, MDA, and 5-HT levels were increased in rats of the model group in comparison to the control group. Elevated mean body weight, paw mechanical pain threshold, food intake, GER and IPR, and serum MTL, GAS, SS, and SOD levels, and reduced serum leptin, VIP, CGRP, MDA, and 5-HT levels were observed in rats of the EA, ACE, and EA + ACE groups relative to the model group. EA combined with ACE treatment was more effective than the EA or ACE treatment alone. EA combined with ACE treatment improves gastrointestinal motility and gastrointestinal hormone levels, promotes food intake, and reduces visceral hypersensitivity in FD rats.

Analysis of Immunobiochemical Parameters in Overweight People in Assessing the Risk of Cardiovascular Diseases.

A comparative analysis of specific immunobiochemical parameters, including natural antibodies (NAb) to endogenous regulators of the cardiovascular system, adrenal and gastrointestinal hormones, was performed in students aged 18-22 years with normal and increased body weight (the body mass index from 18.5 to 24.9 kg/m2 and from 25 to 29.9 kg/m2, respectively). The serum content of NAb and hormones was determined by ELISA. The level of the studied indicators depended on the body mass index value. In overweight subjects, the main immune indicators of the biogenic amine system, renin-angiotensin system, and kinin system exceeded the normal. The cortisol level was higher than in subjects with normal body weight. Aldosterone secretion was less dependent on the ACTH content and was lower than in students with normal body weight. The content of cholecystokinin and gastrin corresponded to the values for overweight. These trends in hormone contents are a predisposing factor for further weight gain. Practical significance of the combined assessment of disturbances in the immunological and biochemical homeostasis has been established. Analysis of the adrenal and gastrointestinal hormones can predict the risk of weight gain, but at the same time, changes in the level of immunological indicators in subjects with increased body weight characterizes the possibility of developing cardiovascular pathologies.

Novel insights into the pathogenic impact of diabetes on the gastrointestinal tract.

Type 2 and type 1 diabetes are common endocrine disorders with a progressively increasing incidence worldwide. These chronic, systemic diseases have multiorgan implications, and the whole gastrointestinal (GI) tract represents a frequent target in terms of symptom appearance and interdependent pathophysiological mechanisms. Metabolic alterations linked with diabetic complications, neuropathy and disrupted hormone homeostasis can lead to upper and/or lower GI symptoms in up to 75% of diabetic patients, with multifactorial involvement of the oesophagus, stomach, upper and lower intestine, and of the gallbladder. On the other hand, altered gastrointestinal motility and/or secretions are able to affect glucose and lipid homeostasis in the short and long term. Finally, diabetes has been linked with increased cancer risk at different levels of the GI tract. The presence of GI symptoms and a comprehensive assessment of GI function should be carefully considered in the management of diabetic patients to avoid further complications and to ameliorate the quality of life. Additionally, the presence of gastrointestinal dysfunction should be adequately managed to improve metabolic homeostasis, the efficacy of antidiabetic treatments and secondary prevention strategies.

Human Gastrointestinal Transit and Hormonal Response to Different Meal Types: A Randomized Crossover Study.

BACKGROUND: The wireless motility capsule (WMC) technique is a noninvasive and radiation-free method for measuring regional and whole gut transit in response to ingestion of a granola bar (SmartBar) or an eggbeater meal. The WMC has the potential to measure gastrointestinal transit in metabolic research as part of a standardized mixed meal tolerance test. OBJECTIVES: To evaluate gastrointestinal transit with the WMC and postprandial plasma/serum concentrations of metabolites and gastrointestinal hormones as well as subjective appetite following ingestion of a SmartBar compared with a standardized mixed meal. METHODS: Fourteen healthy participants [3 men, median (IQR) age 53.8 (45.8; 64.50) y, body weight 63.9 (59.9; 69.7) kg, BMI 23.1 (21.8; 23.9) kg/m2] completed a 2-d crossover study. Following ingestion of either a SmartBar (260 kcal, 7 energy percent (E%) fat, 74E% carbohydrate, and 19E% protein) or a standardized mixed meal (498 kcal, 34E% fat, 49E% carbohydrate, and 17E% protein), participants swallowed the WMC. Blood samples were drawn in the fasted state and postprandially for analyses of gastrointestinal hormones and metabolites. The primary outcome was difference in gastric emptying time between the 2 test days. Wilcoxon signed rank tests were used to test differences between test days. RESULTS: Median (IQR) gastric emptying time was 98.0 (70.0; 113.0) min longer (P = 0.001) and incremental area under the curve of triglyceride, glucose-dependent insulinotropic polypeptide, and peptide YY were 40 mmol/L × min, 45.7%, and 63.7% greater after the standardized mixed meal compared with the SmartBar (all P < 0.001). CONCLUSIONS: The WMC can be used in combination with a standardized mixed meal for evaluation of gastrointestinal transit in healthy men and women. Gastric emptying time was prolonged in response to the standardized mixed meal whereas transit times of the small bowel, colon, and whole gut did not differ between the test meals.

Fortifying a meal with oyster mushroom powder beneficially affects postprandial glucagon-like peptide-1, non-esterified free fatty acids and hunger sensation in adults with impaired glucose tolerance: a double-blind randomized controlled crossover trial.

PURPOSE: Impaired glucose tolerance (IGT) is a pathophysiological condition characterized by insulin resistance with known metabolic consequences such as postprandial hyperglycemia and hypertriglyceridemia. We hypothesized that fortifying a meal with mushrooms rich in ß-glucans may diminish glucose and triglyceride responses by improving postprandial gastrointestinal hormone release. METHODS: In a randomized controlled crossover study, 22 subjects with IGT ingested a meal either enriched with 20 g powder (8.1 g ß-glucans) of oven-dried Pleurotus ostreatus (enriched meal, EN) or without enrichment (control meal, CON). Blood was collected before and repeatedly within 4 h after the meal to determine AUC of glucose (primary outcome), insulin, triglycerides, non-esterified free fatty acids (NEFAs), glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP) and ghrelin. Appetite sensations (hunger, satiety, fullness, and desire to eat) were assessed before and after meal consumption by visual analog scales. RESULTS: Postprandial glucose, insulin, triglycerides, GIP and ghrelin concentrations as well as the corresponding AUCs did not differ between EN and CON. NEFAs-AUC was 14% lower (P = 0.026) and GLP-1-AUC 17% higher (P = 0.001) after EN compared to CON. Appetite ratings did not differ between treatments, except for hunger (AUC 22% lower after EN vs. CON; P = 0.031). CONCLUSION: The observed immediate postprandial metabolic changes indicate that an easily manageable fortification of a single meal with powder from dried oyster mushrooms as ß-glucan source may improve postprandial metabolism. If the effect is preserved long term, this measure can diminish the risk for further development of overweight/obesity and type 2 diabetes in subjects with IGT. CLINICAL TRIAL REGISTRATION: German Clinical Trial Register on 09/08/2018; trial-ID: DRKS00015244.

The many faces of diabetes. Is there a need for re-classification? A narrative review.

The alarming rise in the worldwide prevalence of obesity and associated type 2 diabetes mellitus (T2DM) have reached epidemic portions. Diabetes in its many forms and T2DM have different physiological backgrounds and are difficult to classify. Bariatric surgery (BS) is considered the most effective treatment for obesity in terms of weight loss and comorbidity resolution, improves diabetes, and has been proven superior to medical management for the treatment of diabetes. The term metabolic surgery (MS) describes bariatric surgical procedures used primarily to treat T2DM and related metabolic conditions. MS is the most effective means of obtaining substantial and durable weight loss in individuals with obesity. Originally, BS was used as an alternative weight-loss therapy for patients with severe obesity, but clinical data revealed its metabolic benefits in patients with T2DM. MS is more effective than lifestyle or medical management in achieving glycaemic control, sustained weight loss, and reducing diabetes comorbidities. New guidelines for T2DM expand the use of MS to patients with a lower body mass index.Evidence has shown that endocrine changes resulting from BS translate into metabolic benefits that improve the comorbid conditions associated with obesity, such as hypertension, dyslipidemia, and T2DM. Other changes include bacterial flora rearrangement, bile acids secretion, and adipose tissue effect.This review aims to examine the physiological mechanisms in diabetes, risks for complications, the effects of bariatric and metabolic surgery and will shed light on whether diabetes should be reclassified.

New Insights in the Control of Fat Homeostasis: The Role of Neurotensin.

Neurotensin (NT) is a small peptide with pleiotropic functions, exerting its primary actions by controlling food intake and energy balance. The first evidence of an involvement of NT in metabolism came from studies on the central nervous system and brain circuits, where NT acts as a neurotransmitter, producing different effects in relation to the specific region involved. Moreover, newer interesting chapters on peripheral NT and metabolism have emerged since the first studies on the NT-mediated regulation of gut lipid absorption and fat homeostasis. Intriguingly, NT enhances fat absorption from the gut lumen in the presence of food with a high fat content, and this action may explain the strong association between high circulating levels of pro-NT, the NT stable precursor, and the increased incidence of metabolic disorders, cardiovascular diseases, and cancer observed in large population studies. This review aims to provide a synthetic overview of the main regulatory effects of NT on several biological pathways, particularly those involving energy balance, and will focus on new evidence on the role of NT in controlling fat homeostasis, thus influencing the risk of unfavorable cardio-metabolic outcomes and overall mortality in humans.

Ghrelin, glucagon-like peptide-1, and peptide YY secretion in patients with and without weight regain during long-term follow-up after bariatric surgery: a cross-sectional study.

Introduction: Weight loss after bariatric surgery is attributed, at least in part, to the altered gastrointestinal (GI) hormone secretion, which is thought to be responsible for a number of beneficial metabolic effects. Material and methods: We conducted a cross-sectional study. Twelve patients who underwent laparoscopic sleeve gastrectomy (SG) and 20 patients who underwent a variant of biliopancreatic diversion with Roux-en-Y gastric bypass and long limbs (BPD/RYGB-LL) were evaluated ≥ 7 years postoperatively. Ghrelin, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY) secretion were compared between patients with successful weight loss maintenance (WM group) and patients with weight regain (WR group). Results: In both types of surgery, standard liquid mixed meal (SLMM) ingestion did not result in significant changes in fasting GI hormone levels. Fasting ghrelin levels did not differ between the WM group and the WR group in both types of surgery. In SG patients, SLMM ingestion elicited greater suppression of ghrelin levels in the WM group (p = 0.032). No difference in GLP-1 secretion was observed between the 2 groups of patients in both types of surgery. When patients were examined, regardless of the type of bariatric surgery they had undergone, postprandial PYY levels were lower in the WM group (p < 0.05), while fasting and postprandial PYY levels were correlated positively with an increase in body mass index (BMI) in the evaluation (Spearman's rho ≥ 0.395, p < 0.03). Conclusions: Our data do not support the hypothesis that long-term weight regain after bariatric surgery is associated with an unfavourable GI hormone secretion pattern.

The distribution and chemical coding of enteroendocrine cells in Trypanosoma cruzi-infected individuals with chagasic megacolon.

Chagas disease is caused by the parasite, Trypanosoma cruzi that causes chronic cardiac and digestive dysfunction. Megacolon, an irreversible dilation of the left colon, is the main feature of the gastrointestinal form of Chagas disease. Patients have severe constipation, a consequence of enteric neuron degeneration associated with chronic inflammation. Dysmotility, infection, neuronal loss and a chronic exacerbated inflammation, all observed in Chagas disease, can affect enteroendocrine cells (EEC) expression, which in turn, could influence the inflammatory process. In this study, we investigated the distribution and chemical coding of EEC in the dilated and non-dilated portion of T. cruzi-induced megacolon and in non-infected individuals (control colon). Using immunohistochemistry, EECs were identified by applying antibodies to chromogranin A (CgA), glucagon-like peptide 1 (GLP-1), 5-hydroxytryptamine (5-HT), peptide YY (PYY) and somatostatin (SST). Greater numbers of EEC expressing GLP-1 and SST occurred in the dilated portion compared to the non-dilated portion of the same patients with Chagas disease and in control colon, but numbers of 5-HT and PYY EEC were not significantly different. However, it was noticeable that EEC in which 5-HT and PYY were co-expressed were common in control colon, but were rare in the non-dilated and absent in the dilated portion of chagasic megacolon. An increase in the number of CgA immunoreactive EEC in chagasic patients reflected the increases in EEC numbers summarised above. Our data suggests that the denervation and associated chronic inflammation are accompanied by changes in the number and coding of EEC that could contribute to disorders of motility and defence in the chagasic megacolon.

Effects of a whey protein pre-meal on bone turnover in participants with and without type 2 diabetes-A post hoc analysis of a randomised, controlled, crossover trial.

AIMS: Whey protein may improve bone turnover and have anti-osteoporotic effects. The aim of the present randomised, controlled, crossover trial was to evaluate the effects of a whey protein pre-meal on bone turnover in people with type 2 diabetes and controls. METHODS: Two groups, matched on sex, age and body mass index, comprising 12 participants with and 12 participants without type 2 diabetes were randomly given a pre-meal of whey protein (20 g) or water, which was consumed 15 min before a fat-rich meal or a fat-rich meal supplemented with 20 g whey protein. During a 360-min period, postprandial responses in bone turnover were examined. RESULTS: Osteocalcin, P-procollagen type 1 amino terminal propeptide (P1NP), C-terminal cross-linked telopeptide of type-I collagen (CTX) and parathyroid hormone (PTH) were lower at baseline and PTH, osteocalcin and P1NP were lower during the entire postprandial phase in participants with type 2 diabetes than in participants without type 2 diabetes. We observed similar postprandial responses in bone turnover markers between persons with and without type 2 diabetes. We observed no effect of the whey protein or the water pre-meal on bone turnover markers. The changes were unrelated to secretion of hormones of the gut-bone axis. CONCLUSION: Osteocalcin, P1NP, CTX and PTH all decreased following meal ingestion. We observed no convincing effect of a whey protein pre-meal on bone turnover. However, these results confirm that people with type 2 diabetes have low bone turnover and that the decreased bone formation markers are also extend into the postprandial responses.

Therapeutic potential of targeting intestinal bitter taste receptors in diabetes associated with dyslipidemia.

Intestinal release of incretin hormones after food intake promotes glucose-dependent insulin secretion and regulates glucose homeostasis. The impaired incretin effects observed in the pathophysiologic abnormality of type 2 diabetes have triggered the pharmacological development of incretin-based therapy through the activation of glucagon-like peptide-1 (GLP-1) receptor, including GLP-1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase 4 (DPP4) inhibitors. In the light of the mechanisms involved in the stimulation of GLP-1 secretion, it is a fundamental question to explore whether glucose and lipid homeostasis can be manipulated by the digestive system in response to nutrient ingestion and taste perception along the gastrointestinal tract. While glucose is a potent stimulant of GLP-1 secretion, emerging evidence highlights the importance of bitter tastants in the enteroendocrine secretion of gut hormones through activation of bitter taste receptors. This review summarizes bitter chemosensation in the intestines for GLP-1 secretion and metabolic regulation based on recent advances in biological research of bitter taste receptors and preclinical and clinical investigation of bitter medicinal plants, including bitter melon, hops strobile, and berberine-containing herbs (e.g. coptis rhizome and barberry root). Multiple mechanisms of action of relevant bitter phytochemicals are discussed with the consideration of pharmacokinetic studies. Current evidence suggests that specific agonists targeting bitter taste receptors, such as human TAS2R1 and TAS2R38, may provide both metabolic benefits and anti-inflammatory effects with the modulation of the enteroendocrine hormone secretion and bile acid turnover in metabolic syndrome individuals or diabetic patients with dyslipidemia-related comorbidities.

Fasting oxyntomodulin, glicentin, and gastric inhibitory polypeptide levels are associated with activation of reward- and attention-related brain centres in response to visual food cues in adults with obesity: A cross-sectional functional MRI study.

Postprandial increases in gastrointestinal hormones are associated with reduced energy intake, partially through direct effects on the brain. However, it remains unknown whether the fasting levels of gastrointestinal hormones are associated with altered brain activity in response to visual food stimuli. We therefore performed a whole-brain regression cross-sectional analysis to assess the association between fasting brain activations according to functional magnetic resonance imaging, performed during viewing of highly desirable versus less desirable food images, with fasting levels of five gastrointestinal hormones (glucagon-like peptide [GLP]-1, GLP-2, oxyntomodulin, glicentin and gastric inhibitory polypeptide [GIP]) in 36 subjects with obesity. We observed that fasting blood levels of GIP were inversely associated with the activation of attention-related areas (visual cortices of the occipital lobe, parietal lobe) and of oxyntomodulin and glicentin with reward-related areas (insula, putamen, caudate for both, and additionally orbitofrontal cortex for glicentin) and the hypothalamus when viewing highly desirable as compared to less desirable food images. Future studies are needed to confirm whether fasting levels of oxyntomodulin, glicentin and GIP are associated with the activation of brain areas involved in appetite regulation and with energy intake in people with obesity.

From Entero-Endocrine Cell Biology to Surgical Interventional Therapies for Type 2 Diabetes.

The physiological roles of the enteroendocrine system in relation to energy and glucose homeostasis regulation have been extensively studied in the past few decades. Considerable advances were made that enabled to disclose the potential use of gastro-intestinal (GI) hormones to target obesity and type 2 diabetes (T2D). The recognition of the clinical relevance of these discoveries has led the pharmaceutical industry to design several hormone analogues to either to mitigate physiological defects or target pharmacologically T2D.Amongst several advances, a major breakthrough in the field was the unexpected observation that enteroendocrine system modulation to T2D target could be achieved by surgically induced anatomical rearrangement of the GI tract. These findings resulted from the widespread use of bariatric surgery procedures for obesity treatment, which despite initially devised to induce weight loss by limiting the systemic availably of nutrients, are now well recognized to influence GI hormone dynamics in a manner that is highly dependent on the type of anatomical rearrangement produced.This chapter will focus on enteroendocrine system related mechanisms leading to improved glycemic control in T2D after bariatric surgery interventions.

Quantitation and chemical coding of enteroendocrine cell populations in the human jejunum.

Recent studies reveal substantial species and regional differences in enteroendocrine cell (EEC) populations, including differences in patterns of hormone coexpression, which limit extrapolation between animal models and human. In this study, jejunal samples, with no histologically identifiable pathology, from patients undergoing Whipple's procedure were investigated for the presence of gastrointestinal hormones using double- and triple-labelling immunohistochemistry and high-resolution confocal microscopy. Ten hormones (5-HT, CCK, secretin, proglucagon-derived peptides, PYY, GIP, somatostatin, neurotensin, ghrelin and motilin) were localised in EEC of the human jejunum. If only single staining is considered, the most numerous EEC were those containing 5-HT, CCK, ghrelin, GIP, motilin, secretin and proglucagon-derived peptides. All hormones had some degree of colocalisation with other hormones. This included a population of EEC in which GIP, CCK and proglucagon-derived peptides are costored, and four 5-HT cell populations, 5-HT/GIP, 5-HT/ghrelin, 5-HT/PYY, and 5-HT/secretin cell groups, and a high degree of overlap between motilin and ghrelin. The presence of 5-HT in many secretin cells is consistent across species, whereas lack of 5-HT and CCK colocalisation distinguishes human from mouse. It seems likely that the different subclasses of 5-HT cells subserve different roles. At a subcellular level, we examined the vesicular localisation of secretin and 5-HT, and found these to be separately stored. We conclude that hormone-containing cells in the human jejunum do not comply with a one-cell, one-hormone classification and that colocalisations of hormones are likely to define subtypes of EEC that have different roles.

Relationships of endocrine cells to each other and to other cell types in the human gastric fundus and corpus.

Gastric endocrine cell hormones contribute to the control of the stomach and to signalling to the brain. In other gut regions, enteroendocrine cells (EECs) exhibit extensive patterns of colocalisation of hormones. In the current study, we characterise EECs in the human gastric fundus and corpus. We utilise immunohistochemistry to investigate EECs with antibodies to ghrelin, serotonin (5-HT), somatostatin, peptide YY (PYY), glucagon-like peptide 1, calbindin, gastrin and pancreastatin, the latter as a marker of enterochromaffin-like (ECL) cells. EECs were mainly located in regions of the gastric glands populated by parietal cells. Gastrin cells were absent and PYY cells were very rare. Except for about 25% of 5-HT cells being a subpopulation of ECL cells marked by pancreastatin, colocalisation of hormones in gastric EECs was infrequent. Ghrelin cells were distributed throughout the fundus and corpus; most were basally located in the glands, often very close to parietal cells and were closed cells i.e., not in contact with the lumen. A small proportion had long processes located close to the base of the mucosal epithelium. The 5-HT cells were of at least three types: small, round, closed cells; cells with multiple, often very long, processes; and a subgroup of ECL cells. Processes were in contact with their surrounding cells, including parietal cells. Mast cells had very weak or no 5-HT immunoreactivity. Somatostatin cells were a closed type with long processes. In conclusion, four major chemically defined EEC types occurred in the human oxyntic mucosa. Within each group were cells with distinct morphologies and relationships to other mucosal cells.

Distributions and relationships of chemically defined enteroendocrine cells in the rat gastric mucosa.

This paper provides quantitative data on the distributions of enteroendocrine cells (EEC), defined by the hormones they contain, patterns of colocalisation between hormones and EEC relations to nerve fibres in the rat gastric mucosa. The rat stomach has three mucosal types: non-glandular stratified squamous epithelium of the fundus and esophageal groove, a region of oxyntic glands in the corpus, and pyloric glands of the antrum and pylorus. Ghrelin and histamine were both contained in closed cells, not contacting the lumen, and were most numerous in the corpus. Gastrin cells were confined to the antrum, and 5-hydroxytryptamine (5-HT) and somatostatin cells were more frequent in the antrum than the corpus. Most somatostatin cells had basal processes that in the antrum commonly contacted gastrin cells. Peptide YY (PYY) cells were rare and mainly in the antrum. The only numerous colocalisations were 5-HT and histamine, PYY and gastrin and gastrin and histamine in the antrum, but each of these populations was small. Peptide-containing nerve fibres were found in the mucosa. One of the most common types was vasoactive intestinal peptide (VIP) fibres. High-resolution analysis showed that ghrelin cells were closely and selectively approached by VIP fibres. In contrast, gastrin cells were not selectively innervated by VIP or CGRP fibres. The study indicates that there are distinct populations of gastric EEC and selective innervation of ghrelin cells. It also shows that, in contrast to EEC of the small intestine, the majority of EEC within the stomach contained only a single hormone.