The incretin hormones glucagon like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) have recently received much attention for their roles in type 2 diabetes therapy. GLP-1 stimulated insulin secretion in a glucose-dependent manner and is secreted by intestinal L cells. It also regulates blood glucose concentration, stomach motility, appetite, and body weight. These actions are mediated through G-protein-coupled receptors highly expressed on pancreatic beta cells and also exert indirect metabolic actions. Activation of GLP-1 receptors also produces nonglycemic effects in various tissues. The pleiotropic effects of GLP-1 have been recently reported. The mechanisms identified in preclinical studies have potential translational relevance for the treatment of disease. Here, the nonglycemic effects of GLP-1, especially those on the liver, central nervous system, and bone, were reviewed.
Appetite ; Blood Glucose ; Body Weight ; Central Nervous System ; Enteroendocrine Cells ; Glucagon ; Glucagon-Like Peptide 1 ; Incretins ; Insulin ; Insulin-Secreting Cells ; Liver ; Receptors, G-Protein-Coupled ; Stomach

BACKGROUND AND OBJECTIVES: Type 1 Diabetes Mellitus (T1DM) is an autoimmune disorder resulting out of T cell mediated destruction of pancreatic beta cells. Immunomodulatory properties of mesenchymal stem cells may help to regenerate beta cells and/or prevent further destruction of remnant, unaffected beta cells in diabetes. We have assessed the ability of umbilical cord derived MSCs (UCMSCs) to differentiate into functional islet cells in vitro. METHODS AND RESULTS: We have isolated UCMSCs and allowed sequential exposure of various inducing agents and growth factors. We characterized these cells for confirmation of the presence of islet cell markers and their functionality. The spindle shaped undifferentiated UCMSCs, change their morphology to become triangular in shape. These cells then come together to form the islet like structures which then grow in size and mature over time. These cells express pancreatic and duodenal homeobox -1 (PDX-1), neurogenin 3 (Ngn-3), glucose transporter 2 (Glut 2) and other pancreatic cell markers like glucagon, somatostatin and pancreatic polypeptide and lose expression of MSC markers like CD73 and CD105. They were functionally active as demonstrated by release of physiological insulin and C-peptide in response to elevated glucose concentrations. CONCLUSIONS: Pancreatic islet like cells with desired functionality can thus be obtained in reasonable numbers from undifferentiated UCMSCs in vitro. This could help in establishing a "very definitive source" of islet like cells for cell therapy. UCMSCs could thus be a game changer in treatment of diabetes.
C-Peptide ; Cell- and Tissue-Based Therapy* ; Diabetes Mellitus, Type 1 ; Genes, Homeobox ; Glucagon ; Glucose ; Glucose Transport Proteins, Facilitative ; Insulin* ; Insulin-Secreting Cells ; Intercellular Signaling Peptides and Proteins ; Islets of Langerhans ; Mesenchymal Stromal Cells* ; Pancreatic Polypeptide ; Somatostatin ; Stem Cells ; Umbilical Cord*

BACKGROUND: Despite a recent breakthough in human islet transplantation for treating type 1 diabetes mellitus, the limited availability of donor pancreases remains a major obstacle. Endocrine cells within the gut epithelium (enteroendocrine cells) and pancreatic beta cells share similar pathways of differentiation during embryonic development. In particular, K-cells that secrete glucose-dependent insulinotropic polypeptide (GIP) have been shown to express many of the key proteins found in beta cells. Therefore, we hypothesize that K-cells can be transdifferentiated into beta cells because both cells have remarkable similarities in their embryonic development and cellular phenotypes. METHODS: K-cells were purified from heterogeneous STC-1 cells originating from an endocrine tumor of a mouse intestine. In addition, a K-cell subclone expressing stable Nkx6.1, called "Kn4-cells," was successfully obtained. In vitro differentiation of K-cells or Kn4-cells into beta cells was completed after exendin-4 treatment and serum deprivation. The expressions of insulin mRNA and protein were examined by RT-PCR and immunocytochemistry. The interacellular insulin content was also measured. RESULTS: K-cells were found to express glucokinase and GIP as assessed by RT-PCR and Western blot analysis. RT-PCR showed that K-cells also expressed Pdx-1, NeuroD1/Beta2, and MafA, but not Nkx6.1. After exendin-4 treatment and serum deprivation, insulin mRNA and insulin or C-peptide were clearly detected in Kn4-cells. The intracellular insulin content was also increased significantly in these cells. CONCLUSION: K-cells are an attractive potential source of insulin-producing cells for treatment of type 1 diabetes mellitus. However, more experiments are necessary to optimize a strategy for converting K-cells into beta cells.
Animals ; Blotting, Western ; C-Peptide ; Diabetes Mellitus, Type 1 ; Embryonic Development ; Endocrine Cells ; Enteroendocrine Cells ; Epithelium ; Female ; Glucokinase ; Humans ; Immunohistochemistry ; Insulin ; Insulin-Secreting Cells ; Intestines ; Islets of Langerhans Transplantation ; Mice ; Pancreas ; Peptides ; Phenotype ; Pregnancy ; Proteins ; RNA, Messenger ; Tissue Donors ; Venoms

A putative polypeptide hormone identified as amylin[islet amyloid polypeptide] is synthesized and co-localized with insulin in B cells of pancreatic islets in several animal species including man. However, there is growing evidence that somatostatin cells are also expressed and contained amylin in the pancreatic islets of the rat The aim of the present study was to investigate the immunocytochemical expression of the amylin within the endocrine pancreas of the man, rabbit and guinea pig, with special reference to the possible ability of islet cells other than insulin cells to synthesize amylin. For this purpose serial sections of the pancreatic islets were stainedimmunocytochemically using anti-amylin, anti-insulin, anti-glucagon, anti-somatostatin antisera. In serial sections of pancreatic islets of the man and rabbit, it was shown that amylin immunoreactivity occurred in insulin-reactive B cells predominantly located in interior of the islets. In contrast, amylin immunoreacivity appeared in glucagon-reactive A cells peripherally located in the islets of the guinea pig. These results suggest that in both the man and rabbit, amylin is synthesized by B cells for subsequent co-secretion with insulin, and that in guinea pig, amylin is synthesized by A cells for co-secretion with glucagon. It thus appears that amylin release may be mediated by different secretory mechanisms according to animal species.
Amyloid ; Animals ; B-Lymphocytes ; Glucagon ; Guinea Pigs* ; Guinea* ; Immune Sera ; Immunohistochemistry ; Insulin ; Islet Amyloid Polypeptide* ; Islets of Langerhans* ; Rats ; Somatostatin-Secreting Cells

The purpose of this study was to examine the ultrastructural characteristic of the normal pylorus mucosa, and their structural changes induced by the ligation of common bile duct of the male rabbits weighing about 1.5 kg each. Experiment animals were divided into normal, sham operation, and experimental groups. Common bile duct ligation was performed under ether anesthesia and anjmals were sacrificed on the 1st, 3rd, 5th, 7th and 14th day after operation. The mucosal specimen of the pylorus, were fixed and embedded with common method. The sections were cut on a LKB-V ultratome, and observed under a JEM 100CX II electron microscope. The results were as follow : 1. In the early stages (1st, 3rd, 5th day groups) following the ligation, surface mucous cells have the various electron densities and shape of the mucous granules. In the late stages (7th, 14th day groups) following the ligation, many surface mucose cells containing numerous electron dense mucous granules are seen. 2. In the early stage of the ligation of bile duct, secretory function of EC cells was depressed, but in the later stage, the cells showed recovered secretory activity. 3. Secretory function of D cells was depressed on the early groups after the ligation of common bile duct, but they showed recovered secretory activity from the late groups after the ligation of the common bile duct. 4. Secretory function of G cells was activated on the early groups after the ligation of common bile duct, but they showed depressed secretory activity from the late groups after the ligation of the common bile duct. Considering the above findings, common bile duct ligation probably causes the dysfunction of the pyloric surface mucous cells that results in delayed mucous formation and secretion, and recovered mucous secretory function on the late stages. EC cells and G cells, depressed the secretory activities on the early stages and recovered on the late stages of the ligation of common bile duct. But D cells in the pyloric mucosa was activated on the early groups after the ligation of common bile duct ligation, but they was depressed secretory activities on the late groups.
Anesthesia ; Animals ; Bile Ducts ; Common Bile Duct* ; Ether ; Gastrin-Secreting Cells ; Humans ; Ligation* ; Male ; Mucous Membrane* ; Pylorus ; Rabbits ; Somatostatin-Secreting Cells

BACKGROUND/OBJECTIVES: Cholecystokinin (CCK), a hormone or neuropeptide, is secreted in response to intraluminal nutrients by enteroendocrine I-cells of the intestine and has important physiological actions related to appetite regulation and satiety. The stimulation on CCK secretion from the intestine is of potential relevance for body weight management. Naringenin (4',5,7-trihydroxyflavanone) and its glycoside naringin (naringenin 7-rhamnoglucoside) have been reported to have many biological functions. In the current study, we investigated the question of whether naringenin and naringin could stimulate CCK secretion and then examined the mechanisms involved in CCK release. MATERIALS/METHODS: STC-1 cells were used as a model of enteroendocrine cells. CCK release and changes in intracellular Ca2+ ([Ca2+]i) were measured after incubation of cells with naringenin and naringin for 1 h. RESULTS: Naringenin caused significant (P < 0.05) stimulation of CCK secretion, but naringin did not. In addition, regarding the secretory mechanisms, naringenin-induced CCK secretion involved increases in [Ca2+]i, influx of extracellular Ca2+, at least in part, and activation of TRP channels, including TRPA1. CONCLUSION: Findings of this study suggest that naringenin could have a role in appetite regulation and satiety.
Appetite ; Appetite Regulation ; Body Weight ; Cholecystokinin* ; Enteroendocrine Cells ; Intestines ; Neuropeptides

Hesperetin (3',5,7-trihydroxy 4'-methoxyflavanone) and its glycoside hesperidin (hesperetin 7-rhamnoglucoside) in oranges have been reported to possess pharmacological effects related to anti-obesity. However, hesperetin and hesperidin have not been studied on suppressive effects on appetite. This study examined that hesperetin and hesperidin can stimulate the release of cholecystokinin (CCK), one of appetite-regulating hormones, from the enteroendocrine STC-1 cells, and then examined the mechanisms involved in the CCK release. Hesperetin significantly and dose-dependently stimulated CCK secretion with an EC50 of 0.050 mM and increased the intracellular Ca2+ concentrations ([Ca2+]i) compared to the untreated control. The stimulatory effect by hesperetin was mediated via the entry of extracellular Ca2+ and the activation of TRP channels including TRPA1. These results suggest that hesperetin can be a candidate biomolecule for the suppression of appetite and eventually for the therapeutics of obesity.
Appetite ; Cholecystokinin* ; Citrus sinensis ; Enteroendocrine Cells ; Hesperidin ; Obesity

OBJECTIVETo study regulative action of mica monomer granule preparation on gastrin (GAS), somatostatin (SS) and G cells as well as D cells of gastric mucosa in experimental chronic atrophic gastritis (CAG) rat.

METHODCAG rats were treated with mica monomer granule preparation with three different dosages--high, moderate and low level respectively. Changes of blood serum GAS, blood plasma SS and G cells as well as D cells of gastric mucosa in CAG rats were observed and detected with ELISA method, RIA method and immunocytochemistry method.

RESULTMica monomer granule of three different dosages could increase the quantity of G cells as well as D cells of gastric mucosa and the concentration of blood serum GAS and decrease the content of blood plasma SS in CAG rat at different level respectively. It was more effective in high and moderate dosage groups.

CONCLUSIONMica has the pharmacological action of protecting gastric mucosa, promoting the palingenesis of gastric gland and enhancing blood stream of gastric mucosa consequently to abate the inflammation reaction of gastric mucosa. Its effective mechanism is associated with the neuroendocrine regulative mechanism of promoting the secretion of gastric acid and gastric pepsin by increasing the amount of G cells as well as D cells and the concentration of blood serum GAS, and reducing inhibiting action on GAS secretion and enhancing the secretion of GAS by decreasing the content of SS.

Aluminum Silicates ; administration & dosage ; pharmacology ; Animals ; Dose-Response Relationship, Drug ; Gastric Mucosa ; pathology ; Gastrin-Secreting Cells ; drug effects ; Gastrins ; blood ; Gastritis, Atrophic ; blood ; pathology ; Materia Medica ; administration & dosage ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Somatostatin ; blood ; Somatostatin-Secreting Cells ; drug effects

Carcinoid tumors are rare endocrine neoplasms arising from the enterochromaffin or enterochromaffin-like cells. Gastric carcinoids associated with autoimmune atrophic gastritis and hypergastrinemia, are usually multiple and the prognosis are better compared to solotary lesions with out hypergastrinemia. Gastric carcinoids are commonly associated with other endocrine disorders or tumors, but any associations with autoimmune disorders other than autoimmune atrophic gastritis have rarely been reported. Sjogren's syndrome is an autoimmune exocrinopathy that primarily affects the salivary glands, but it can also involve almost any other part of the gut. The most common form of gastrointestinal involvement in Sjogren's syndrome is chronic atrophic gastritis, which can lead to hypergastrinemia and the subsequent development of carcinoid. However, gastric carcinoid tumor associated with Sjogren's syndrome has not yet been reported on. To the best of our knowledge, this is the first such case in the world. We report on this case along with review of the related literature.
Carcinoid Tumor* ; Enterochromaffin-like Cells ; Gastritis, Atrophic ; Prognosis ; Salivary Glands ; Sjogren's Syndrome*

Incretin hormones are produced by enteroendocrine cells (EECs) in the intestine in response to ingested nutrient stimuli. The incretin effect is defined as the difference in the insulin secretory response between the oral glucose tolerance test and an isoglycemic intravenous glucose infusion study. The pathophysiology of the decreased incretin effect has been studied as decreased incretin sensitivity and/or β-cell dysfunction per se. Interestingly, robust increases in endogenous incretin secretion have been observed in many types of metabolic/bariatric surgery. Therefore, metabolic/bariatric surgery has been extensively studied for incretin physiology, not only the hormones themselves but also alterations in EECs distribution and genetic expression levels of gut hormones. These efforts have given us an enormous understanding of incretin biology from synthesis to in vivo behavior. Further innovative studies are needed to determine the mechanisms and targets of incretin hormones.
Bariatric Surgery ; Biology ; Enteroendocrine Cells ; European Union ; Glucose ; Glucose Tolerance Test ; Incretins* ; Insulin ; Intestines* ; Physiology