Cilostazol, Not Aspirin, Reduces Ischemic Brain Injury via Endothelial Protection in Spontaneously Hypertensive Rats

Abstract

Background and Purpose-It is well-established that hypertension leads to endothelial dysfunction in the cerebral artery.Recently, cilostazol has been used for the secondary prevention of ischemic stroke. Among antiplatelet drugs, phosphodiesterase inhibitors including cilostazol have been shown to have protective effects on endothelial cells. The aim of the present study is to investigate the effects of cilostazol and aspirin on endothelial nitric oxide synthase (eNOS) phosphorylation in the cerebral cortex, endothelial function, and infarct size after brain ischemia in spontaneously hypertensive rats (SHR). Methods-Five-week-old male SHR received a 5-week regimen of chow containing 0.1% aspirin, 0.1% cilostazol, 0.3% cilostazol, or the vehicle control. The levels of total and Ser 1177 -phosphorylated eNOS protein in the cerebral cortex were evaluated by Western blot. To assess the contribution of eNOS in maintaining cerebral blood flow, we monitored cerebral blood flow by laser-Doppler flowmetry after L-N 5 -(1-iminoethyl)ornithine infusion. Additionally, we evaluated residual microperfusion using fluorescence-labeled serum protein and infarct size after transient focal brain ischemia. Results-In SHR, the blood pressure and heart rate were similar among the groups. Cilostazol-treated SHR had a significantly higher ratio of phospho-eNOS/total eNOS protein than vehicle-treated and aspirin-treated SHR. Treating with cilostazol, but not aspirin, significantly improved cerebral blood flow response to L-N 5 -(1-iminoethyl)ornithine. Cilostazol also increased residual perfusion of the microcirculation and reduced brain damage after ischemia compared to vehicle control and aspirin. Conclusions-These findings indicate that cilostazol, but not aspirin, can attenuate ischemic brain injury by maintaining endothelial function in the cerebral cortex of SHR. (Stroke. 2011;42:2571-2577.)Key Words: brain ischemia Ⅲ endothelial function Ⅲ hypertension Ⅲ phosphodiesterase-3 inhibitor H ypertension is one of the most important risk factors for cerebrovascular disease and is closely associated with endothelial dysfunction. Some studies observed endothelial dysfunction in patients with hypertension or cerebrovascular disease. 1,2 In hypertensive animal models, hypertension impairs endothelium-dependent vasodilatation, cerebrovascular autoregulation, and cerebral blood flow (CBF) responses, and it exacerbates ischemic brain damage. [3][4][5][6] Endothelial dysfunction is often characterized by a decrease in the bioavailability of endothelium-derived nitric oxide (NO). In endothelial cells, NO is produced by endothelial nitric oxide synthase (eNOS), and eNOS activity is regulated primarily by calcium-calmodulin activation and multisite phosphorylation of specific serine or threonine residues. Most importantly, phosphorylation of eNOS-Ser 1177 is thought to play a crucial role in eNOS activation. In a cerebral ischemia model, modification of the eNOS-Ser 1177 phosphorylation state modulated CBF and the outcome of ischemic injury. 7 Th...

Nitric Oxide: Considerations for the Treatment of Ischemic Stroke

“…It was shown that dipyramidol augmented the neuroprotective effects of statins in an eNOS-dependent way (Kim et al, 2008). The putative mechanism involves an increase in eNOS S1177 phosphorylation, as demonstrated in spontaneously hypertensive rats (Oyama et al, 2011) based on the reduction in postischemic brain damage following pretreatment with PDE inhibitor cilostazol. While these are the first encouraging data suggesting that PDE inhibitors can also increase eNOS activity in stroke patients (Serebruany et al, 2011), clinical use of PDE inhibitors is so far restricted to secondary prevention of ischemic stroke: Two large clinical trials (ESPRIT: European/Australasian Stroke Prevention in Reversible Ischaemia Trial (Halkes et al, 2007), ESPS-2: European Stroke Prevention Study 2 (Diener et al, 1996)) proved that dipyramidole in combination with acetylsalicylic acid (ASA) is more effective in preventing secondary ischemic insults than ASA alone.…”

The Role of the Host Defense System in the Development of Cerebral Vasospasm: Analogies between Atherosclerosis and Subarachnoid Hemorrhage

“…Cilostazol (CZ), a selective inhibitor of type III phosphodiesterase in platelets or VSMCs which has antithrombotic properties [126], an inhibitory action on the progression of carotid intima-media thickness [127], and a protective action on endothelial cell functions [128], has been approved for the treatment of symptoms related to peripheral arterial occlusive disease and symptoms of intermittent claudication and for the prevention of recurrent cerebral infarction in Japan [129]. CZ prevented experimental cerebral vasospasm [130,131,132] and also reduced moderate to severe vasospasm on angiogram from 42% in controls to 15% in the treated group in humans (n = 50) [133].…”

Antidepressant Effects of Aripiprazole Augmentation for Cilostazol-Treated Mice Exposed to Chronic Mild Stress after Ischemic Stroke

“…Cilostazol (CLS) possesses a powerful means to produce various pleiotropic effects through the elevation of intracellular cyclic adenosine monophosphate (cAMP) levels, resulting in the increased phosphorylation of the cAMP response element binding protein (CREB) [15,16,17]. CLS has been widely approved for the secondary prevention of ischemic stroke [18]. …”