The objective of this study was to study the effect of diabetic
hyperglycemia on astrocytes after forebrain
ischemia.
Streptozotocin (STZ)-injected hyperglycemic and vehicle-injected normoglycemic rats were subjected to 15 minutes of forebrain
ischemia. The brains were harvested in
sham-operated controls and in animals with 1 and 6 h of recirculation following
ischemia. Brain damage was accessed by haematoxylin and
eosin (H&E) staining, cleaved
caspase-3 immunohistochemistry and TdT-mediated-dUTP nick end labeling (TUNEL).
Anti-GFAP antibody was employed to study astrocytes. The results showed that the 15-minute
ischemia caused neuronal death after 1 and 6 h of reperfusion as revealed by increased numbers of karyopyknotic cells,
edema, TUNEL-positive and active caspase-3-positive cells.
Ischemia also activated astrocytes in the cingulated cortex as reflected by astrocyte stomata
hypertrophy, elongated dendrites and increases in the number of dendrites, and immunoreactivity of GFAP. Diabetic
hyperglycemia further enhanced neuronal death and suppressed
ischemia-induced astrocyte activation. Further, diabetes-damaged astrocytes have increased withdrawal of the astrocyte end-foot from the cerebral blood vessel wall. It is concluded that diabetes-induced suppression and damages to astrocytes may contribute to its detrimental effects on recovery from
cerebral ischemia.