INFLUENCE OF AGE, HYPERGLYCEMIA, LEPTIN, AND NPY ON ISLET BLOOD-FLOW IN OBESE-HYPERGLYCEMIC MICE

This study aimed to elucidate possible age-related changes in islet bl ood perfusion in lean and obese C57BL/6 mice. Obese mice aged 1 mo wer e hyperglycemic and hyperinsulinemic and had an increased islet blood flow compared with age-matched lean mice. This augmented blood flow co uld be abolished by pretreatment with leptin. The islet blood perfusio n was, in contrast to this, markedly decreased in obese 6- to 7-mo-old animals compared with age-matched lean mice. Reversal of hyperglycemi a, but not hyperinsulinemia, in these obese mice with phlorizin normal ized the islet blood flow. Spontaneous reversal of hyperglycemia, but not hyperinsulinemia, was seen in the 12-mo-old obese mice. Islet bloo d perfusion in obese mice at this age did not differ compared with lea n mice. It is suggested that the initial increase in islet blood flow in obese mice is due to the leptin deficiency The subsequent decrease in islet blood perfusion is probably caused by the chronic hyperglycem ia. The described islet blood flow changes may be of importance for im pairment of islet function in obese-hyperglycemic mice.