Possible contribution of the non-proteolytic activation of prorenin to the development of insulin resistance in fructose-fed rats

Recent studies have shown that blocking non-proteolytically activated prorenin with a decoy peptide for the handle region of the prorenin prosegment (HRP) inhibits the development of microvascular complications in diabetic animals. In the present study, we investigated whether non-proteolytic activation of prorenin contributes to the development of fructose-induced insulin resistance. Rats were fed a standard diet (n = 10), a 60% high fructose diet (n = 16), or a high fructose diet + HRP (0.1 mg kg^-1 day ^-1, n = 16) for 10 weeks. Fructose-fed rats showed higher systolic blood pressure (SBP), fasting plasma triglycerides, total cholesterol and insulin levels; which, except for SBP, were suppressed by HRP. The responses of plasma glucose and insulin levels to oral glucose loading were significantly greater in fructose-fed rats than in standard diet-fed rats. The HRP normalized the enhanced responses of plasma glucose and insulin levels that were observed in fructose-fed rats. Moreover, HRP suppressed the enhanced prorenin activation and angiotensin II formation in the soleus muscle of fructose-fed rats. These data suggest that local angiotensin II generation in skeletal muscle, induced by non-proteolytic activation of prorenin, contributes to the development of insulin resistance induced by a high fructose diet.