Effects of crocin and voluntary exercise, alone or combined, on heart VEGF-A and HOMA-IR of HFD/STZ induced type 2 diabetic rats.

Abstract

Hyperglycemia is the main risk factor for microvascular complications in type 2 diabetes. Crocin and voluntary exercise have anti-hyperglycemic effects in diabetes. In this research, we evaluated the effects of crocin and voluntary exercise alone or combined on glycemia control and heart level of VEGF-A. Animals were divided into eight groups as: control (con), diabetes (Dia), crocin (Cro), voluntary exercise (Exe), crocin and voluntary exercise (Cro-Exe), diabetic-crocin (Dia-Cro), diabetic-voluntary exercise (Dia-Exe), diabetic-crocin-voluntary exercise (Dia-Cro-Exe). Type 2 diabetes was induced by a high-fat diet (4weeks) and injection of streptozotocin (STZ) (i.p, 35mg/kg). Animals received oral administration of crocin (50mg/kg) or performed voluntary exercise alone or together for 8weeks. Oral glucose tolerance test (OGTT) was performed on overnight fasted control, diabetic and treated rats after 8weeks of treatment. Then, serum insulin and heart VEGF-A protein levels were measured. Crocin combined with voluntary exercise significantly decreased blood glucose levels (p<0.001) and insulin resistance (HOMA-IR) (p<0.001) compared to diabetic group. VEGF-A level was significantly (p<0.01) lower in Dia group compared to control group. The combination of crocin and voluntary exercise significantly enhanced VEGF-A protein levels in Dia-Cro-Exe and Cro-Exe group compared to diabetic and control groups, respectively; p<0.001 and p<0.05. Crocin combined with voluntary exercise improved insulin resistance (HOMA-IR) and reduced glucose levels in diabetic rats. Since both crocin and voluntary exercise can increase VEGF-A protein expression in heart tissue, they probably are able to increase angiogenesis in diabetic animals.