-Obesity is a risk factor for stroke, but the early effects of high-fat diet (HFD) on neurovascular function and ischemic stroke outcomes remain unclear. The goal of this study was to test the hypotheses that HFD beginning early in life 1) impairs neurovascular coupling, 2) causes cerebrovascular dysfunction, and 3) worsens short-term outcomes after cerebral ischemia. Functional hyperemia and parenchymal arteriole (PA) reactivity were measured in rats after 8 wk of HFD. The effect of HFD on basilar artery function after middle cerebral artery occlusion (MCAO) and associated O-GlcNAcylation were assessed. Neuronal cell death, infarct size, hemorrhagic transformation (HT) frequency/severity, and neurological deficit were evaluated after global ischemia and transient MCAO. HFD caused a 10% increase in body weight and doubled adiposity without a change in lipid profile, blood glucose, and blood pressure. Functional hyperemia and PA relaxation were decreased with HFD. Basilar arteries from stroked HFD rats were more sensitive to contractile factors, and acetylcholine-mediated relaxation was impaired. Vascular O-GlcNAcylated protein content was increased with HFD. This group also showed greater mortality rate, infarct volume, HT occurrence rate, and HT severity and poor functional outcome compared with the control diet group. These results indicate that HFD negatively affects neurovascular coupling and cerebrovascular function even in the absence of dyslipidemia. These early cerebrovascular changes may be the cause of greater cerebral injury and poor outcomes of stroke in these animals. cerebral ischemia; high-fat diet; hemorrhagic transformation; neurovascular coupling; vascular dysfunction OBESITY IS an independent risk factor for acute ischemic stroke (AIS) (19,36). An alarming recent report showed that the prevalence of AIS dramatically increased in children and young adults, which positively correlated with increases in risk factors including obesity, lipid disorders, and diabetes (13). Clinical studies also suggest that obesity is an independent predictor of unfavorable functional outcome and mortality in AIS patients treated with tissue plasminogen activator (tPA), the only therapeutic option these patients have (39,40). Given that stroke is the leading cause of disability and that the obesity epidemic is on the rise these clinical and social problems are expected to get worse, and therefore early interventions are necessary. While experimental studies in genetic or diet-induced obesity models have shown increased cerebral infarct size and poor outcomes of stroke (7,25,32,33,41), the early impact of a high-fat diet (HFD) before the development of obesity on AIS injury and functional outcomes is not known.It is known that the brain relies heavily on constant blood flow for proper function. Two important mechanisms that contribute to the regulation of cerebral blood perfusion are autoregulatory behavior of cerebral vessels and functional hyperemia upon increased neuronal activity (11,16,20). HFD can negatively af...

Abstract-Hyperglycemia, which increases O-linked ␤-N-acetylglucosamine (O-GlcNAc) proteins, leads to changes in vascular reactivity. Because vascular dysfunction is a key feature of arterial hypertension, we hypothesized that vessels from deoxycorticosterone acetate and salt (DOCA-salt) rats exhibit increased O-GlcNAc proteins, which is associated with increased reactivity to constrictor stimuli. A rterial hypertension is a multifactorial condition estimated to affect 25% of the adult population or Ϸ1 billion people worldwide. The prevalence of hypertension is predicted to increase to 30% by 2025 (ie, 1.56 billion people will harbor this condition in the next several years). 1,2 Considered a major risk factor for cardiovascular disease, which is the leading cause of morbidity and mortality in most Western countries, arterial hypertension is also responsible for Ͼ7 million deaths. In addition, estimates of expenditures related to hypertension and its complications in 2007 indicate that total direct costs will approach $66.4 billion. 3 Prevention of hypertension and hypertension-associated end-organ damage is one of the major therapeutic aims in cardiovascular medicine. Although current drugs are effective in many patients, there are still a great number of patients that are unresponsive even to combination therapy. This clearly indicates that new advances in the field are required.Abnormal vascular reactivity, including impaired endotheliumdependent relaxation and enhanced sensitivity to vasoconstrictors, is a hallmark of hypertensive disease. However, our current understanding of the cellular and molecular mechanisms leading to vascular dysfunction in hypertension is still incomplete. Many proteins important in cardiovascular function, including kinases, phosphatases, transcription factors, and cytoskeleton proteins, 4,5 have been identified as targets for O-linked ␤-N-acetylglucosamine (O-GlcNAc)ylation, a post-translational modification that influences protein expression, degradation, and trafficking.Although it is clear that O-GlcNAcylation plays a critical role in the regulation of cell function, there is a

Abstract-Disturbances in the regulation of cytosolic calcium (Ca 2ϩ ) concentration play a key role in the vascular dysfunction associated with arterial hypertension. Stromal interaction molecules (STIMs) and Orai proteins represent a novel mechanism to control store-operated Ca 2ϩ entry. Although STIMs act as Ca 2ϩ sensors for the intracellular Ca 2ϩ stores, Orai is the putative pore-forming component of Ca 2ϩ release-activated Ca 2ϩ channels at the plasma membrane. We hypothesized that augmented activation of Ca 2ϩ release-activated Ca 2ϩ /Orai-1, through enhanced activity of STIM-1, plays a role in increased basal tonus and vascular reactivity in hypertensive animals. Endothelium-denuded aortic rings from Wistar-Kyoto and stroke-prone spontaneously hypertensive rats were used to evaluate contractions because of Ca 2ϩ influx. Depletion of intracellular Ca 2ϩ stores, which induces Ca 2ϩ release-activated Ca 2ϩ activation, was performed by placing arteries in Ca 2ϩ free-EGTA buffer. The addition of the Ca 2ϩ regular buffer produced greater contractions in aortas from stroke-prone spontaneously hypertensive rats versus Wistar-Kyoto rats. Thapsigargin (10 mol/L), an inhibitor of the sarcoplasmic reticulum Ca 2ϩ ATPase, further increased these contractions, especially in stroke-prone spontaneously hypertensive rat aorta. Addition of the Ca 2ϩ release-activated Ca 2ϩ channel inhibitors 2-aminoethoxydiphenyl borate (100 mol/L) or gadolinium (100 mol/L), as well as neutralizing antibodies to STIM-1 or Orai-1, abolished thapsigargin-increased contraction and the differences in spontaneous tone between the groups. Expression of Orai-1 and STIM-1 proteins was increased in aorta from stroke-prone spontaneously hypertensive rats when compared with Wistar-Kyoto rats. These results support the hypothesis that both Orai-1 and STIM-1 contribute to abnormal vascular function in hypertension. Augmented activation of STIM-1/Orai-1 may represent the mechanism that leads to impaired control of intracellular Ca 2ϩ levels in hypertension.