Diabetes mellitus impairs poststroke neovascularization in the ipsilateral and contralateral hemispheres. A, Representative brain section depicting the region of interest in the ipsilateral and contralateral hemisphere shown in red and yellow squares. B, Representative images contrasting ipsilateral and contralateral zones across the groups. C, Plot depicting vascular volume across groups and treatment arm aP<0.05 vs sham control or ipsilateral control and diabetes mellitus, bP<0.05 vs control or diabetes mellitus plus metformin. D, Plot depicting vascular surface area across groups, aP<0.05 vs sham control, bP<0.05 vs ipsilateral diabetes mellitus, cP<0.05 vs control or diabetes mellitus plus metformin, and dP=0.0018 vs sham. Data were analyzed with a 2×2 design for disease (control vs diabetes mellitus) and intervention (sham vs stroke) in the ipsilateral or contralateral hemispheres. There was significant interaction indicating important differences in vascularization at baseline and after stroke in the diabetes mellitus group. To determine the impact of glycemic control on poststroke vascularization, 1-way ANOVA was used (control, diabetes mellitus, and diabetes mellitus plus metformin) and P values are shown on the graphs and post hoc analyses are marked by letters. Mean±SEM; n=6 to 9.
Diabetes mellitus impairs poststroke cerebral neovascularization at the infarct border zone. A, Representative image depicting the localization of the infarct border zone. B, Representative images comparing vascular density at infarct border zone taken under ×10 objective. C, Graphical representation of the % vascular density around the area of infarction in all the groups. Mean±SEM; n=4 to 6. GFAP indicates glial fibrillary acidic protein.
Diabetes mellitus decreases isolectin staining (red, non–fluorescein isothiocyanate [FITC]-perfused vessels) after stroke indicating impairment of new vessel formation. A, Representative images comparing nonperfused vessels at day 14 in the infarct border zone imaged using a ×63 objective. White arrows represent the nonperfused vessel islands protruding from the perfused vessels. B, Graphical representation of the % nonperfused vasculature in the peri-infarct zone in all the groups. Mean±SEM; n=4 to 5.
Diabetes mellitus exacerbates astrogliosis after stroke. A, Representative images showing astrocytic morphology in the infarct border zone and nonlesional hemisphere, as well as in the corresponding regions in sham animals. B, Diabetic stroke dramatically increases astrocytic swelling compared with control strokes and metformin treatment decreased swelling. C, Number of astrocytic projections is significantly increased even after 14 days in diabetic stroke compared with control and glycemic intervention conserved astrocytic processes. Blue, indicates fluorescein isothiocyanate (FITC)-perfused vasculature; green, glial fibrillary acidic protein (GFAP); and red, neuronal nuclei. Mean±SEM; n=3 to 4.
Glycemic intervention after stroke improves sensorimotor functions in diabetes mellitus. A and B, Temporal profile of sensorimotor functions represented as composite neurological score. Diabetes mellitus significantly reduced the neurological scores after stroke. Improvement in the neurological scores was slower in the diabetic stroke group compared with control stroke. Glycemic intervention with metformin improved and restored the composite neurological scores comparable with the control group. B, Temporal profile of forelimb grip strength shows a similar trend. The drop in the forelimb grip strength is not restored 14 days after stroke in the diabetic group compared with control. Glycemic intervention with metformin improved the forelimb grip strength. aP<0.05 vs diabetes mellitus, bP<0.01 vs diabetes mellitus, eP<0.001 vs diabetes mellitus, carea under the curve (AUC) P=0.012 vs diabetes mellitus, dAUC P=0.0007 vs diabetes mellitus. Mean±SEM; n=6 to 8.
Anxiety-like symptoms are aggravated in diabetic stroke. A and B, Graphical representation of the temporal changes in the percentage of time spent in the open and closed arm of the elevated plus maze. Diabetic groups tend to spend more time in the closed arm compared with the control groups and ischemic reperfusion injury worsened this outcome. C, Freezing time was dramatically increased after stroke in the diabetic group that already showed augmented time spent in the center of the maze before stroke. aP<0.001, bP<0.05, cP<0.01 vs control, Mean±SEM; n=6 to 8. D, Plot of the recognition index of all the groups at baseline and after stroke at various time points show that diabetes mellitus dampens the recognition index and stroke injury further worsens this index. Metformin intervention restored the recognition index in the diabetic stroke group. aP<0.001, bP<0.01, carea under the curve P<0.001 vs diabetes mellitus. Mean±SEM; n=6 to 8.
