TAILIEUCHUNG - Báo cáo Y học: Expression of glucose transporter-2, glucokinase and mitochondrial glycerolphosphate dehydrogenase in pancreatic islets during rat ontogenesis

To gain better insight into the insulin secretory activity of fetalbcells in response to glucose, the expression of glucose transporter 2 (GLUT-2), glucokinase and mitochondrial glycerol phosphate dehydrogenase (mGDH) were studied. Expression ofGLUT-2mRNA and protein in pancreatic islets and liver was signi®cantly lower in fetal and suckling rats than in adult rats. | Eur. J. Biochem. 269 119-127 2002 FEBS 2002 Expression of glucose transporter-2 glucokinase and mitochondrial glycerolphosphate dehydrogenase in pancreatic islets during rat ontogenesis Marta Garcia-Flores1 Jose Antonio Zueco1 Joaquin Arenas2 and Enrique Blazquez1 1 Department of Biochemistry and Molecular Biology Faculty of Medicine Complutense University Madrid Spain 2Clinical Biochemistry Service 12 de Octubre Hospital Madrid Spain To gain better insight into the insulin secretory activity of fetal b cells in response to glucose the expression of glucose transporter 2 GLUT-2 glucokinase and mitochondrial glycerol phosphate dehydrogenase mGDH were studied. Expression of GLUT-2 mRNA and protein in pancreatic islets and liver was significantly lower in fetal and suckling rats than in adult rats. The glucokinase content of fetal islets was significantly higher than of suckling and adult rats and in liver the enzyme appeared for the first time on about day 20 of extrauterine life. The highest content of hexokinase I was found in fetal islets after which it decreased progressively to the adult values. Glucokinase mRNA was abundantly expressed in the islets of all the experimental groups whereas in liver it was only present in adults and 20-day-old suckling rats. In fetal islets GLUT-2 and glucokinase protein and their mRNA increased as a function of increasing glucose concentration whereas reduced mitochondrial citrate synthase succinate dehydrogenase and cytochrome c oxidase activities and mGDH expression were observed. These Endings together with those reported by others may help to explain the decreased insulin secretory activity of fetal b cells in response to glucose. Keywords glucokinase GLUT-2 mitochondrial glycerol-3-phosphate dehydrogenase ontogeny pancreatic islets. In many mammals the ability of pancreatic b cells to secrete insulin in response to glucose appears after birth 1 and even the decreased glucose tolerance process endures for the whole suckling .

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