Taurine Supplementation Enhances Insulin Secretion Without Altering Islet Morphology in Non-obese Diabetic Mice.

Abstract

Taurine (TAU) is a sulfated amino acid that improves pancreatic islet function and regulates β-cell mass in pre- and diabetic states. We herein analyzed glucose homeostasis and islet morphofunction in non-obese diabetic (NOD) mice supplemented with 2 % TAU in their drinking water from birth until 90-days of age. TAU-supplemented female NOD mice (TAU group) showed a better glucose tolerance without modification in insulinemia, when compared to non-supplemented NOD mice (CTL). Glucose-induced insulin secretion was higher in islets isolated from female and male TAU groups. In addition, a better insulin release was observed at 30 mM K+ in islets from female TAU mice. These effects were accompanied by a higher total intracellular Ca2+ concentration in islets from female and male TAU mice. TAU-treated mice did not show any alteration in β-cell and islet areas, compared with CTL mice. Islets from TAU female mice presented a higher ratio of phosphorylated Akt and ERK (extracellular signal-regulated kinase) related to Akt and ERK protein content, respectively, in comparison with CTL islets. Additional experiments using isolated islets from Swiss mice showed that 3 mM TAU prevented the reduction in insulin secretion induced by 12 h incubation with IL1-β or IL1-β + IFN-γ. In conclusion, TAU supplementation improved NOD islet function without altering endocrine pancreatic morphometry, an effect that may be associated with a protective TAU effect upon cytokine-induced islet dysfunction, together with an improved protein expression of Akt and ERK.