Reversal of abnormal retinal hemodynamics in diabetic rats by acarbose, an α-glucosidase inhibitor

Abstract

Acarbose is an inhibitor of intestinal α-glucosidase and has been reported to decrease blood glucose concentrations and glycosuria in diabetic patients and animals. In this study we investigated whether this drug could prevent the abnormalities detected in retinal circulation of diabetic rats. Longitudinal paired studies were performed and the changes in retinal circulation were analyzed using video based fluorescein angiography (VFA) methodology in the same animal. Baseline VFA recordings were obtained from 41 rats. These rats were separated into 4 different groups: In group A (n = 12), diabetes was induced by streptozotocin (STZ) injection and the rats were fed with acarbose (40 mg/100 g powdered chow) mixed into regular rat chow; In group B (n = 10), diabetes was induced by STZ injection and the rats were fed with normal chow; In group C (n = 9), the non-diabetic rats were fed with acarbose; In group D (n = 10), the non-diabetic rats were fed with normal chow. At the end of 2 weeks, all rats again underwent VFA recordings. Blood glucose levels and body weights of rats were monitored during the experiment. The mean blood glucose concentration of Group B was raised from 98.5 ± 8.7 to 342 ± 30 mg/dl after STZ injection while in Group A, this change in glucose level was partially ameliorated by acarbose (from 102 ± 15 to 247 ± 48 mg/dl). In Group C and D, the blood glucose levels were not significantly changed during the experiment. In Group B, a paired t-test analysis demonstrated that retinal blood flow in the untreated diabetic rats decreased significantly (p = 0.0001) 2 weeks after induction of diabetes (76.4 ± 24.1 pixel²/s) compared to baseline (141.3 ± 20.3 pixel²/s). In contrast, the acarbose treated diabetic rats in Group A showed no significant differences between blood flow before (140.1 ± 21.6 pixel²/s) and after induction of diabetes (133.4 ± 16.5 pixel²/s). There were no significant changes in retinal blood flow in the non-diabetic rat groups (Group C acarbose fed and Group D normal chow). These results suggest that acarbose can prevent the abnormalities detected in retinal circulation probably associated with decreasing the blood glucose concentration.

Key Words:

• acarbose
• hemodynamics
• retina
• diabetes
• rats