Temporal profile of focal cerebral ischemic damage in type 2 diabetes

Abstract

While 90% clinical patients have type 2 diabetes, most experimental studies have focused on the effect of streptozotocin‐induced type 1 diabetes on cerebral ischemic injury. We have previously shown smaller infarcts in a lean type 2 diabetes model, Goto‐Kakizaki (GK) rats, after permanent and transient cerebral ischemia. However, the effect of extended period of type 2 diabetes on cerebral perfusion and stroke outcome remains unknown. Accordingly, the cerebral blood perfusion was measured with scanning laser Doppler imaging system and the infarct size and edema were evaluated after permanent middle cerebral artery occlusion induced ischemia in 10 and 18 wk old control Wistar and diabetic GK rats. Both 10 and 18 wk GK rats showed lower baseline cerebral perfusion (2.75 ± 0.19 and 2.76 ± 0.28 pixels/mm2, n=6‐9, p<0.01) compared to those obtained in Wistar rats. There was no difference in infarct size between young and old Wistars, while both groups of GK rats showed smaller infarct (10 wk GK, 29.07 ± 7.33% and 18 wk GK, 12.25 ± 1.38, p<0.05 vs. 10 or 18 wk Wistar). Both GK groups had increased edema when compared to controls. These results suggest that mild‐to‐moderate increases in blood glucose provide neuroprotection early in the disease process but effects of the severity and longer duration of diabetes on ischemic reperfusion injury remain to be determined.