ICAM-1 expression in distinct brain regions were compared by measuring the OD of positive cells in the brains of control and diabetic rat with immunohistochemical staining. (A). The representative image of ICAM-1 expression in the cerebral cortex of control rats. (B). The representative image of ICAM-1 expression in the cerebral cortex of diabetic rats. (C). The OD comparison of ICAM-1 expression positive cell in cerebral cortex between control and diabetes rats. ICAM-1 expression in the cerebral cortex of diabetic rats significantly increases compared with control rats (*P < 0.05). (D). Schematic representation indicates brain regions where ICAM-1 expression is significantly altered in diabetic rats and the rank order (from more to fewer) of expression quantity change in distinct regions of the integral brain. (E). The comparison of ICAM-1 expression quantity change in distinct brain regions. ICAM-1 expression quantity change is significantly different in distinct brain regions of diabetic rats (*P < 0.05). Bar = 100 μm.