title: Taurine supplementation modulates glucose homeostasis and islet function.
abstract: Taurine is a conditionally essential amino acid for human that is involved in the control of glucose homeostasis; however, the mechanisms by which the amino acid affects blood glucose levels are unknown. Using an animal model, we have studied these mechanisms. Mice were supplemented with taurine for 30 d. Blood glucose homeostasis was assessed by intraperitoneal glucose tolerance tests (IPGTT). Islet cell function was determined by insulin secretion, cytosolic Ca2+ measurements and glucose metabolism from isolated islets. Islet cell gene expression and translocation was examined via immunohistochemistry and quantitative real-time polymerase chain reaction. Insulin signaling was studied by Western blot. Islets from taurine-supplemented mice had: (i) significantly higher insulin content, (ii) increased insulin secretion at stimulatory glucose concentrations, (iii) significantly displaced the dose-response curve for glucose-induced insulin release to the left, (iv) increased glucose metabolism at 5.6 and 11.1-mmol/L concentrations; (v) slowed cytosolic Ca2+ concentration ([Ca2+]i) oscillations in response to stimulatory glucose concentrations; (vi) increased insulin, sulfonylurea receptor-1, glucokinase, Glut-2, proconvertase and pancreas duodenum homeobox-1 (PDX-1) gene expression and (vii) increased PDX-1 expression in the nucleus. Moreover, taurine supplementation significantly increased both basal and insulin stimulated tyrosine phosphorylation of the insulin receptor in skeletal muscle and liver tissues. Finally, taurine supplemented mice showed an improved IPGTT. These results indicate that taurine controls glucose homeostasis by regulating the expression of genes required for glucose-stimulated insulin secretion. In addition, taurine enhances peripheral insulin sensitivity.
authors: Department of Physiology and Biophysic, Institute of Biology, State University of Campinas, Campinas 13083-862, Brasil.
authors: Everardo M
authors: EM
authors: Carneiro
authors: Marcia Q
authors: MQ
authors: Latorraca
authors: Eliana
authors: E
authors: Araujo
authors: Marta
authors: M
authors: Beltrá
authors: Maria J
authors: MJ
authors: Oliveras
authors: Mónica
authors: M
authors: Navarro
authors: Genoveva
authors: G
authors: Berná
authors: Francisco J
authors: FJ
authors: Bedoya
authors: Licio A
authors: LA
authors: Velloso
authors: Bernat
authors: B
authors: Soria
authors: Franz
authors: F
authors: Martín
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D019587:Dietary Supplements; D015870:Gene Expression / Q000187:drug effects; D018398:Homeodomain Proteins / Q000032:analysis; D006706:Homeostasis / Q000187:drug effects; D007328:Insulin / Q000097:blood; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects; D011972:Receptor, Insulin / Q000378:metabolism; D013654:Taurine / Q000097:blood / Q000494:pharmacology*; D015534:Trans-Activators / Q000032:analysis; D014443:Tyrosine / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D018398:Homeodomain Proteins; D007328:Insulin; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D013654:Taurine; D014443:Tyrosine; D011972:Receptor, Insulin; D002118:Calcium