title: The effect of glucagon-like peptide-1 in the management of diabetes mellitus: cellular and molecular mechanisms.
abstract: Incretins, such as glucagon-like peptide-1 (GLP)-1, have been shown to elevate plasma insulin concentration. The purpose of this study is to investigate the cellular and molecular basis of the beneficial effects of GLP-1. Normal and diabetic male Wistar rats were treated with GLP-1 (50 ng/kg body weight) for 10 weeks. At the end of the experiment, pancreatic tissues were taken for immunohistochemistry, immunoelectron microscopy and real-time polymerase chain reaction studies. Samples of blood were retrieved from the animals for the measurement of enzymes and insulin. The results show that treatment of diabetic rats with GLP-1 caused significant (P < 0.05) reduction in body weight gain and blood glucose level. GLP-1 (10(-12)-10(-6) M) induced significant (P < 0.01) dose-dependent increases in insulin release from the pancreas of normal and diabetic rats compared to basal. Diabetes-induced abnormal liver (aspartate aminotransferase and alanine aminotransferase) and kidney (blood urea nitrogen and uric acid) parameters were corrected in GLP-1-treated rats compared to controls. GLP-1 treatment induced significant (P < 0.05) elevation in the expression of pancreatic duodenal homeobox-1, heat shock protein-70, glutathione peroxidase, insulin receptor and GLP-1-receptor genes in diabetic animals compared to controls. GLP-1 is present in pancreatic beta cells and significantly (P < 0.05) increased the number of insulin-, glutathione reductase- and catalase-immunoreactive islet cells. The results of this study show that GLP-1 is co-localized with insulin and seems to exert its beneficial effects by increasing cellular concentrations of endogenous antioxidant genes and other genes involved in the maintenance of pancreatic beta cell structure and function.
authors.affiliation: Department of Biology, College of Science, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Lotfy
authors.forename: Jaipaul
authors.initials: J
authors.lastname: Singh
authors.forename: Hameed
authors.initials: H
authors.lastname: Rashed
authors.forename: Saeed
authors.initials: S
authors.lastname: Tariq
authors.forename: Erika
authors.initials: E
authors.lastname: Zilahi
authors.forename: Ernest
authors.initials: E
authors.lastname: Adeghate
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002374:Catalase / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology*; D000077270:Exenatide; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000187:drug effects; D005934:Glucagon / Q000378:metabolism; D052216:Glucagon-Like Peptide 1 / Q000494:pharmacology / Q000627:therapeutic use*; D005951:Glucose Tolerance Test; D005980:Glutathione Reductase / Q000378:metabolism; D007328:Insulin / Q000097:blood / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000201:enzymology / Q000473:pathology / Q000648:ultrastructure; D007668:Kidney / Q000503:physiopathology; D008055:Lipids / Q000097:blood; D008099:Liver / Q000503:physiopathology; D008297:Male; D010455:Peptides / Q000378:metabolism; D017208:Rats, Wistar; D013997:Time Factors; D014688:Venoms / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D007328:Insulin; D008055:Lipids; D010455:Peptides; D014688:Venoms; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D000077270:Exenatide; D002374:Catalase; D005980:Glutathione Reductase