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International Journal of Experimental Diabetes Research
Volume 1, Issue 3, Pages 185-193
http://dx.doi.org/10.1155/EDR.2000.185

Correlation Between Pancreatic Islet Uncoupling Protein-2 (UCP2) mRNA Concentration And Insulin Status in Rats

1Laboratoire de Physiopathologie de la Nutrition, CNRS ESA 7059, Université Paris 7-Denis Diderot, Paris, France
2Département de Physlologe, Unversité Laval, Québec, Canada
3CCNRS ESA 5018, Université Paul Sabatier, Toulouse, France
4CEREMOD CNRS UPR 9078, 9, rue Jules Hetzel, Meudon 92190, France

Accepted 8 March 2000

Copyright © 2000 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Hypothesizing that UCP2 may influence insulin secretion by modifying the ATP/ADP ratio within pancreatic islets, we have investigated the expression of intraislet UCP2 gene in rats showing insulin oversecretion (non-diabetic Zucker fa/fa obese rats, glucose-infused Wistar rats) or insulin undersecretion (fasting and mildly diabetic rats). We found that in Zucker fa/fa obese rats, hyperinsulinemia (1222 ± 98 pmol/1 vs. 128 ± 22 pmol/1 in lean Zucker rats) was accompanied by a significant increase in UCP2 mRNA levels. In rat submitted to a 5 day infusion with glucose, hyperinsulinemia (1126 ± 101 pmol/l vs. 215 ± 25 pmol/1 in Wistar control rats), coincided with an enhanced intraislet UCP2 gene expression, whereas a 8h or a 2 day-infusion did not induce significant changes in UCP2 mRNA expression. In rats made hypoinsulinemic and mildly diabetic by the injection of a low dose of streptozotocin, and in 4-day-fasting rats (plasma insulin 28 ± 5 pmol/1) UCP2 gene expression was sharply decreased. A 3-day-fast was ineffective. The data show the existence of a time-dependent correlation between islet mRNA UCP2 and insulin that may be interpreted as an adaptative response to prolonged insulin excess.