The regional distribution and relative frequency of some endocrine cells in the pancreas of the carp, Cyprinus carpio Linnaeus, belonging to the family Cyprinidae in the order Cypriniformes, were observed using specific mammalian antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (hPP) by peroxidase antiperoxidase (PAP) method. The pancreas was divided into four regions (principal and secondary islets, exocrine and pancreatic duct regions). In addition, the pancreatic islet regions were further subdivided into three regions (central, mantle and peripheral regions) and the pancreatic duct regions were subdivided into two regions (epithelial and subepithelial regions). Spherical to spindle or occasionally round to oval shaped immunoreactive (IR) cells were demonstrated in the pancreatic islets, exocrine and pancreatic duct. In the principal islet regions, some cells were also detected in the other regions, most of insulin- and somatostatin-IR cells were located in the central regions, and glucagon- and hPP-IR cells were situated in the peripheral regions. In this regions, insulin-IR cells were most predominant cell types and then, glucagon, somatostatin and hPP in that order. In the secondary islet regions, the regional distribution and relative frequency of these four types of endocrine cells were quite similar to those of the principal islets except for cell clusters consisted of hPP-IR cells that were situated in the peripheral to mantle regions. In the pancreatic duct regions, all four major pancreatic endocrine cells were demonstrated in the inter-epithelial cells and/or basal regions of the epithelial linning. In addition, cell clusters composed of numerous insulin-, moderate glucagon- and somatostatin-IR cells of low frequency were also observed in the subepithelial regions of the pancreatic duct. In the exocrine regions, insulin-, glucagon-, somatostatin- and hPP-IR cells were located in the inter-acinus regions with rare, a few, moderate and moderate frequencies, respectively. In conclusion, the regional distribution and relative frequency of four major pancreatic endocrine cells, insulin-, glucagon-, somatostatin- and hPP-IR cells, in the pancreas of the carp showed general patterns which were observed in other stomachless teleost. However, some species- dependent different distributional patterns and/or relative frequencies were also demonstrated.
Animals ; Carps/*metabolism ; Female ; Glucagon/metabolism ; Immunohistochemistry/veterinary ; Insulin/metabolism ; Male ; Pancreas/cytology/*metabolism ; Pancreatic Polypeptide/metabolism ; Somatostatin/metabolism

OBJECTIVETo establish Caco2 cell line with stable expression of glucagon like peptide-2 receptor( GLP-2R) , in order to establish an in vitro model for the study of protective mechanism of GLP-2 of the intestinal tract.

METHODSThe GLP-2R/pcDNA3. 1 ( + ) plasmid was verified by restriction endonuclease and sequencing , and then it was transfected into Caco2 cells with lipofectamine. After G418 selection, the clones with stable expression of GLP-2R were obtained by limited dilution cloning and expanding. The mRNA and protein expression of GLP-2R in normal human intestine, Caco2 cells, HER293, VE cells, as well as in transfected Caco2 cells were determined with RT-PCR and Western blot.

RESULTSThe sequence of GLP-2R/pcDNA 3. 1 plasmid was correct. No expression of GLP-2R mRNA and protein was found in HER293 and VE cells, but weak expression were found in Caco2 cells, and strong expression was found in normal human intestines. The expression of GLP-2R mRNA and protein expression in Caco2/GLP-2R ( + ) cells were obviously increased after transfection.

CONCLUSIONGLP-2R has special distribution. The expression of GLP-2R is weak in normal Caco2 cells. The establishment of Caco2/GLP-2R ( + ) cellular model is beneficial for the further research of the mechanism of action of GLP-2.

Caco-2 Cells ; Cellular Structures ; metabolism ; Cloning, Molecular ; Gene Expression ; Genetic Vectors ; Glucagon-Like Peptide 2 ; genetics ; metabolism ; Glucagon-Like Peptide-2 Receptor ; Humans ; Receptors, Glucagon ; genetics ; metabolism ; Transfection

OBJECTIVETo investigate the effects of activation of the GLP-1 receptor on the p38MAPK signaling pathway in hepatic stellate cells (HSCs).

METHODSHSCs were isolated and identified according to morphological features; the levels of GLP-1R protein were determined by western blotting.The HSCs were randomly divided into a control grouP (normal saline treatment) and experimental grouP(liraglutide treatment); after 120 hours, the expression of p38MAPK mRNA was examined by RT-PCR and of phosphorylated (p)-p38MAPK protein was detected by western blotting.

RESULTSGLP-1R proteins were detected in the HSCs. Compared with the control group, the experimental group showed significantly decreased p38MAPK mRNA and p-p38MAPK protein (both P < 0.01).

CONCLUSIONThe p38MAPK signaling pathway could be down-regulated when GLP-1R is activated in HSCs.

Cells, Cultured ; Glucagon-Like Peptide 1 ; analogs & derivatives ; pharmacology ; Glucagon-Like Peptide-1 Receptor ; Hepatic Stellate Cells ; metabolism ; Humans ; Liraglutide ; MAP Kinase Signaling System ; RNA, Messenger ; Receptors, Glucagon ; metabolism ; p38 Mitogen-Activated Protein Kinases ; metabolism

There is a close correlation between type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) in the course of pathophysiological processes. The neuroprotective action of glucagon-like peptide 1 (GLP-1), a latest drug for clinical treatment of T2DM, is being more deeply investigated at present, and a novel therapeutic strategy for AD with GLP-1 has been proposed boldly. This review mainly discussed the correlation of pathogenesis between T2DM and AD, the synthesis and secretion of GLP-1, the distribution and physiological effects of GLP-1 receptor in the brain, and the progresses on the study of GLP-1 in the treatment of AD.
Alzheimer Disease ; drug therapy ; physiopathology ; Amyloid beta-Peptides ; drug effects ; metabolism ; Animals ; Brain ; metabolism ; Diabetes Mellitus, Type 2 ; physiopathology ; Glucagon-Like Peptide 1 ; pharmacology ; therapeutic use ; Glucagon-Like Peptide-1 Receptor ; Humans ; Neuroprotective Agents ; pharmacology ; therapeutic use ; Receptors, Glucagon ; metabolism

Through phage display, we tried to find out whether the N-terminal fragment of glucogan-like peptide 1 receptor (nGLP-1R) still had binding activity to Exendin-4 after missing one or two gene segments. By error-prone PCR, We constructed a randomly mutated phage display peptide library with different length of the N-terminal (21-145 residues) extracellular domain of glucogan-like peptide 1 receptor (GLP-1R) from rat lung. A mutant named EP16 without binding activity was found by ELISA. Through sequence alignment we found that EP16 missed the first 20 and last 10 amino acids and the 52nd tryptophan was mutated to arginine. In order to determine why Ep16 did not show its binding ability to Exendin-4, a wild type EP16 without the first 20 and last 10 amino acids and nGLP-1R(W52R) was constructed in which the 52nd tryptophan was mutated to arginine. The contrastive analysis showed that the substitution of W52R led to a markedly reduced binding ability of EP16. The mutation of the conserved W52 could change the biologic activity of the protein. The lack of the first 20 and last 10 amino acids had no effect on its biologic activity. Therefore, the mutation of a single amino acid residue of the key sequence could change the biologic activity of the nGLP-1R.
Amino Acid Sequence ; Amino Acid Substitution ; Animals ; Binding Sites ; Glucagon-Like Peptide-1 Receptor ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Mutation ; Peptide Fragments ; chemistry ; genetics ; metabolism ; Peptides ; metabolism ; Protein Binding ; Rats ; Receptors, Glucagon ; chemistry ; genetics ; metabolism ; Venoms ; metabolism

The regional distribution and relative frequency of the pancreatic endocrine cells in the C57BL/6 mouse were studied by immunohistochemical method using four types of specific mammalian antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (PP). The pancreas of mouse could be divided into three portions; pancreatic islets, pancreatic duct and exocrine portions, and pancreatic islets were further subdivided into three regions (central, mantle and peripheral regions) according to their located types of immunoreactive cells and pancreatic duct portions were also subdivided into two regions (epithelial and connective tissue regions). In the pancreatic islet portions, although some cells were also demonstrated in the mantle regions, most of insulin-immunoreactive cells were located in the central regions and they were randomly dispersed in the whole pancreatic islets. Glucagon-immunoreactive cells were detected in the mantle and peripheral regions. Their relative frequencies in the peripheral regions were somewhat numerous than those of the mantle regions. Somatostatin-immunoreactive cells were detected in the mantle and peripheral regions. However, no PP-immunoreactive cells were demonstrated in the pancreatic islets of C57BL/6 mouse. In the pancreatic duct portions, rare glucagon-immunoreactive cells were situated in the epithelial regions. Cell clusters that consisted of glucagon- or somatostatin- immunoreactive cells were found in some case of connective tissue regions of pancreatic ducts. However, insulin- and PP-immunoreactive cells were not detected in the epithelial nor connective tissue regions. In the exocrine portions, all four types of immunoreactive cells except for PP cells were demonstrated in the C57BL/6 mouse. However, no PP-immunoreactive cells were demonstrated. In conclusion, regional distribution of endocrine cells in the pancreas of C57BL/6 mouse was similar to that of mammals, especially other rodents except for topographically different distribution of endocrine cells compared to that of other rodents.
Animals ; Female ; Glucagon/metabolism ; Immunohistochemistry ; Insulin/metabolism ; Islets of Langerhans/cytology/*metabolism ; Male ; Mice ; Mice, Inbred C57BL/*metabolism ; Pancreatic Polypeptide/metabolism ; Somatostatin/metabolism

The regional distribution and relative frequency of insulin-, glucagon-, somatostatin- and pancreatic polypeptide (PP)-producing endocrine cells in the pancreas of BALB/c mouse were investigated by immunohistochemical method. The pancreas of mice was divided into two portions; pancreatic islets and exocrine portions, and pancreatic islets were further subdivided into two regions (central and peripheral regions) and the relative frequency and regional distribution of immunoreactive cells against insulin, glucagon, somatostatin and PP antisera were monitored. In the pancreatic islet portions, insulin-immunoreactive cells were located in the central regions and they were randomly dispersed in the whole pancreatic islets in some case of the small islets. Quite different from those of other mammals, glucagon-immunoreactive cells were dispersed throughout central to peripheral regions in case of large islets and in the smaller ones, most of these cells were situated in the peripheral regions. Somatostatin-immunoreactive cells were detected in the peripheral regions with various frequencies. Although some cells were demonstrated in the central regions of pancreatic islets, most of PP-immunoreactive cells were located in the peripheral regions. In the exocrine portions, all four types of immunoreactive cells were demonstrated in the BALB/c mouse. Some peculiar distributional patterns of pancreatic endocrine cells were found in BALB/c mouse, especially in case of glucagon-immunoreactive cells.
Animals ; Female ; Glucagon/*metabolism ; Immunohistochemistry/veterinary ; Insulin/metabolism ; Islets of Langerhans/cytology/*metabolism ; Male ; Mice ; Mice, Inbred BALB C/*metabolism ; Pancreatic Polypeptide/metabolism ; Somatostatin/metabolism

Nesidioblastosis is a term used to describe pathologic overgrowth of pancreatic islet cells. It also means maldistribution of islet cells within the ductules of exocrine pancreas. Generally, nesidioblastosis occurs in beta-cell and causes neonatal hyperinsulinemic hypoglycemia or adult noninsulinoma pancreatogenous hypoglycemia syndrome. Alpha-cell nesidioblastosis and hyperplasia is an extremely rare disorder. It often accompanies glucagon-producing marco- and mircoadenoma without typical glucagonoma syndrome. A 35-year-old female was referred to our hospital with recurrent acute pancreatitis. On radiologic studies, 1.5 cm sized mass was noted in pancreas tail. Cytological evaluation with EUS-fine-needle aspiration suggested serous cystadenoma. She received distal pancreatectomy. The histologic examination revealed a 1.7 cm sized neuroendocrine tumor positive for immunohistochemical staining with glucagon antibody. Multiple glucagon-producing micro endocrine cell tumors were scattered next to the main tumor. Additionally, diffuse hyperplasia of pancreatic islets and ectopic proliferation of islet cells in centroacinar area, findings compatible to nesidioblastosis, were seen. These hyperplasia and almost all nesidioblastic cells were positive for glucagon immunochemistry. Even though serum glucagon level still remained higher than the reference value, she has been followed-up without any evidence of recurrence or hormone related symptoms. Herein, we report a case of alpha-cell nesidioblastosis and hyperplasia combined with glucagon-producing neuroendocrine tumor with literature review.
Adult ; Chromogranin A/blood ; Female ; Glucagon/*metabolism ; Glucagon-Secreting Cells/metabolism ; Humans ; Hyperplasia/complications/*diagnosis ; Islets of Langerhans/metabolism/ultrasonography ; Nesidioblastosis/complications/*diagnosis ; Neuroendocrine Tumors/complications/*diagnosis/pathology ; Pancreas/*pathology ; Tomography, X-Ray Computed

Peptide dual agonists toward both glucagon-like peptide 1 receptor (GLP-1R) and glucagon receptor (GCGR) are emerging as novel therapeutics for the treatment of type 2 diabetes mellitus (T2DM) patients with obesity. Our previous work identified a Xenopus GLP-1-based dual GLP-1R/GCGR agonist termed xGLP/GCG-13, which showed decent hypoglycemic and body weight lowering activity. However, the clinical utility of xGLP/GCG-13 is limited due to its short in vivo half-life. Inspired by the fact that O-GlcNAcylation of intracellular proteins leads to increased stability of secreted proteins, we rationally designed a panel of O-GlcNAcylated xGLP/GCG-13 analogs as potential long-acting GLP-1R/ GCGR dual agonists. One of the synthesized glycopeptides 1f was found to be equipotent to xGLP/GCG-13 in cell-based receptor activation assays. As expected, O-GlcNAcylation effectively improved the stability of xGLP/GCG-13 in vivo. Importantly, chronic administration of 1f potently induced body weight loss and hypoglycemic effects, improved glucose tolerance, and normalized lipid metabolism and adiposity in both db/db and diet induced obesity (DIO) mice models. These results supported the hypothesis that glycosylation is a useful strategy for improving the in vivo stability of GLP-1-based peptides and promoted the development of dual GLP-1R/GCGR agonists as antidiabetic/antiobesity drugs.
Mice ; Animals ; Glucagon-Like Peptide 1/metabolism* ; Receptors, Glucagon/therapeutic use* ; Xenopus laevis/metabolism* ; Diabetes Mellitus, Type 2/drug therapy* ; Glycopeptides/therapeutic use* ; Obesity/drug therapy* ; Hypoglycemic Agents/pharmacology* ; Peptides/pharmacology*

This study was performed to observe the changes of glucose-related hormones and the morphological change including ultrastructure of the pancreatic islets in the male Otsuka Long-Evans Tokushima Fatty rat. Area under the curve (AUC) of glucose at the 30th (709 +/- 73 mg.h/dL) and at the 40th week (746 +/- 87 mg.h/ dL) of age were significantly higher than that at the 10th week (360 +/- 25 mg.h/ dL). AUC of insulin of the 10th week was 2.4 +/- 0.9 ng.h/mL, increased gradually to 10.8 +/- 8.3 ng.h/mL at the 30th week, and decreased to 1.8 +/- 1.2 ng.h/mL at the 40th week. The size of islet was increased at 20th week of age and the distribution of peripheral alpha cells and central beta cells at the 10th and 20th weeks was changed to a mixed pattern at the 40th week. On electron microscopic examination, beta cells at the 20th week showed many immature secretory granules, increased mitochondria, and hypertrophied Golgi complex and endoplasmic reticulum. At the 40th week, beta cell contained scanty intracellular organelles and secretory granules and apoptosis of acinar cell was observed. In conclusion, as diabetes progressed, increased secretion of insulin was accompanied by increases in size of islets and number of beta-cells in male OLETF rats showing obese type 2 diabetes. However, these compensatory changes could not overcome the requirement of insulin according to the continuous hyperglycemia after development of diabetes.
Animals ; Body Weight ; Diabetes Mellitus, Type 2/*metabolism/pathology ; Disease Models, Animal ; Glucagon/*metabolism ; Insulin/*metabolism ; Islets of Langerhans/*metabolism/pathology/ultrastructure ; Male ; Rats ; Rats, Inbred OLETF