Cilostazol Protects Against Brain White Matter Damage and Cognitive Impairment in a Rat Model of Chronic Cerebral Hypoperfusion

Abstract

Background and Purpose— White matter lesions contribute to cognitive impairment in poststroke patients. The present study was designed to assess the neuroprotective mechanisms of cilostazol, a potent inhibitor of type III phosphodiesterase, through signaling pathways that lead to activation of transcription factor cAMP-responsive element binding protein (CREB) phosphorylation using rat chronic cerebral hypoperfusion model. Methods— Rats underwent bilateral common carotid artery ligation. They were divided into the cilostazol group (n=80) and the vehicle (control) group (n=80). Performance at the Morris water maze task and immunohistochemistry for 4-hydroxy-2-nonenal (HNE), glutathione- S -transferase-pi (GST-pi), ionized calcium-binding adaptor molecule 1, phosphorylated CREB (p-CREB), Bcl-2, and cyclooxygenase-2 (COX-2) were analyzed at baseline and at 3, 7, 14, 21, and 28 days after hypoperfusion. Result— Cilostazol significantly improved spatial learning memory (6.8±2.3 seconds; P <0.05) at 7 days after hypoperfusion. Cilostazol markedly suppressed accumulation of HNE-modified protein and loss of GST-pi–positive oligodendrocytes in the cerebral white matter during the early period after hypoperfusion ( P <0.05). Cilostazol upregulated p-CREB and Bcl-2 ( P <0.05), increased COX-2 expression, and reduced microglial activation in the early period of hypoperfusion. Conclusion— Our results indicate that cilostazol exerts a brain-protective effect through the CREB phosphorylation pathway leading to upregulation of Bcl-2 and COX-2 expressions and suggest that cilostazol is potentially useful for the treatment of cognitive impairment in poststroke patients.