Macrovascular disease of coronaries and cerebral arteries in streptozotocin-induced diabetic rats. A controlled, comparative study

The aim of this study was to demonstrate the macrovascular disease in streptozotocin-induced diabetic rats and assess any possible differences between the histopatholological changes of the coronaries and cerebral arteries. Hearts and brains were obtained after 4 weeks (short-term experimental diabetes, 10 rats) and 12 weeks (long-term experimental diabetes, 10 rats) of streptozotocin injection. Sham injected, control rats were studied in parallel. Muscular-type arteries of 0.10-0.15 mm were examined and semiquantitatively classified either as normal, or slightly, or moderately, or severely thickened by light microscopy: While the arterial wall appeared normal in all sham-injected rats, a varying degree of hyperplasia of the muscular layer and deposition of fibrinoid material resulting in arterial stenosis was prominent in streptozotocin-injected rats. In the group of short-term diabetes there was a slight thickening of the cerebral arteries in the majority of the rats (8/10 rats), while thickening of the coronaries was moderate (9/10 rats). Further progression of arterial wall thickening in both cerebral and coronary arteries was observed in the long-term diabetic group. The mean severity of lesions was significantly higher in the coronaries than in cerebral arteries, both in the short-term (p < 0.0005) and long-term diabetes (p < 0.02). Moreover, by paired statistics within individual animals, we confirmed that wall thickening was significantly more severe in coronaries than cerebral arteries in both groups. These findings suggest an accelerated progress of macrovascular disease in the heart as compared to the brain in the streptozotocin-induced diabetic rat. Although histopathological changes in humans do not always mirror clinical severity, the differences in the macrovascular disease between heart and brain in experimental diabetes may be relevant to the higher relative risk of myocardial infarction compared to stroke for people with diabetes, as compared to people without diabetes.