Abstract
Abstract only Diabetes is a widespread disease, and stroke is one of the serious complications of diabetes. Antidiabetic therapy increases the risk of recurrent hypoglycemia (RH). We have previously shown that RH exposure leads to severe post-ischemic hypoperfusion at least up to 80 minutes after ischemia and increases the extent of ischemic brain injury in insulin-treated diabetic (ITD) rats. However, the total duration for which these perfusion deficits last is unknown. Thus, we evaluated cerebral blood flow up to 7 days post-ischemia in RH-exposed ITD rats using laser speckle imaging. Diabetic male rats were treated for hyperglycemia using insulin pellets, were assigned randomly to either hyperinsulinemic euglycemia (ITD+RH+Glucose control; n=7) or hyperinsulinemic hypoglycemia (ITD+RH; n=7) groups (3 h duration) (Figure B-C) and were subjected to transient global cerebral ischemia overnight after the last episode of hyperinsulinemic euglycemia or hyperinsulinemic hypoglycemia. We evaluated cerebral perfusion at baseline (pre-ischemia), 1 h, 24 h, 3 d, 5 d, and 7 d post-ischemia. The cerebral ischemia in RH-exposed ITD rats resulted in a significant decrease in percentage change in cerebral blood flow as compared to the control rats when quantified 1 hour (23%, p<0.01) and 1 day (17%, p<0.05) after cerebral ischemia. However, the percentage changes in cerebral blood flow in ITD+RH group were not significantly different from that of the control group at 3, 5, and 7 days after ischemia (Figure A, D). The cerebral blood flow post-ischemia at 1-hour (24%) and 1-day (18%) was significantly lower (p<0.001 each) while at 3 (12%, p<0.05), 5 (25%, p<0.05), and 7 days (29%, p<0.01) was significantly higher than that of the baseline values in RH-exposed ITD rats. The cerebral blood flow at 1 hour, 1 day, and 3 days after ischemia in ITD + RH + glucose rats was not significantly different from the baseline values. The cerebral blood flow at 5 (19%, p<0.05) and 7 (42%, p<0.001) days after ischemia in ITD + RH + glucose rats was significantly higher than the baseline values. Our results show that RH exposure induces severe post-ischemic hypoperfusion for at least ≈24 hours after ischemia in young male ITD rats. Next, we aim to study the duration of the effect of RH on post-ischemic hypoperfusion in female ITD rats and to identify the underlying mechanism causing this effect in the animal model of diabetes. Acknowledgment: NIH (NS122808).