Yoshio Omote

Rivaroxaban and Apixaban Reduce Hemorrhagic Transformation After Thrombolysis by Protection of Neurovascular Unit in Rat

Background and Purpose— This study aimed to assess the risk and benefit of tissue-type plasminogen activator treatment after oral anticoagulation with rivaroxaban or apixaban compared with warfarin or placebo. Methods— Pretreatment with warfarin (0.2 mg/kg per day), rivaroxaban (2 mg/kg per day), apixaban (10 mg/kg per day), or vehicle (0.5% carboxymethyl cellulose sodium salt) was performed for 7 days. Transient middle cerebral artery occlusion was then induced for 120 minutes, followed by reperfusion with tissue-type plasminogen activator (10 mg/kg per 10 mL). Clinical parameters, including cerebral infarction volume, hemorrhagic volume, and blood coagulation, were examined. Twenty-four hours after reperfusion, markers for the neurovascular unit at the peri-ischemic lesion were immunohistochemically examined in brain sections, and matrix metalloproteinase-9 activity was measured by zymography. Results— The paraparesis score was significantly improved in the rivaroxaban-pretreated group compared with the warfarin-pretreated group. Intracerebral hemorrhage was observed in the warfarin-pretreated group, and this was reduced in the rivaroxaban and apixaban-pretreated groups compared with the vehicle group. Marked dissociation of astrocyte foot processes and the basal lamina or pericytes was observed in the warfarin-pretreated group, and this was improved in the rivaroxaban and apixaban-pretreated groups. Furthermore, activation of matrix metalloproteinase-9 in the ipsilateral warfarin-pretreated brain was greatly reduced in rivaroxaban- and apixaban-pretreated rats. Conclusions— This study shows a lower risk of intracerebral hemorrhage after tissue-type plasminogen activator treatment in rats with ischemic stroke that are pretreated with rivaroxaban and apixaban compared with pretreatment with warfarin. Reducing neurovascular dissociation by rivaroxaban and apixaban compared with warfarin could partly explain a reduction in hemorrhagic complications reported in clinical studies.

Clinical and Pathological Improvement in Stroke-Prone Spontaneous Hypertensive Rats Related to the Pleiotropic Effect of Cilostazol

Background and Purpose— Cerebral infarction is a major cause of death or decreasing activities of daily living. This study aimed to investigate the efficacy of commonly used antiplatelet drugs on stroke and motor and cognitive functions in relation to oxidative stress markers and insulin-like growth factor 1 receptor (IGF-1R). Methods— Stroke-prone spontaneously hypertensive rats were treated with vehicle, aspirin, clopidogrel, and cilostazol from 8 to 10 weeks of age. Physiological parameters, regional cerebral blood flow, and serum lipids were examined. Motor and cognitive functions were evaluated weekly by the Rotorod and water maze task. Spontaneous infarct volume, oxidative stress markers for lipid, protein, and DNA at the ischemic boundary zone of spontaneous infarction, and the IGF-1R-positive cell ratio in the hippocampus were immunohistochemically examined in brain sections. IGF-1R&bgr; expression in the hippocampus was assessed by Western blotting. Results— The antiplatelet drugs, cilostazol and clopidogrel, reduced the spontaneous infarct volume more than aspirin. Only cilostazol improved motor and cognitive functions with a significant increase (P<0.05) in the memory-related IGF-1R-positive ratio and IGF-1R&bgr; expression in the hippocampus. Cilostazol reduced the 4 oxidative stress markers in affected neurons in stroke-prone spontaneously hypertensive rats regardless of blood pressure, regional cerebral blood flow, or serum lipid levels. Conclusions— The present results suggest that a possible pleiotropic effect of cilostazol resulted in the reduction of spontaneous infarct volume and preservation of motor and spatial cognitive functions. The increase of IGF-1R-positive cells in the hippocampal CA1 region could partly explain the preservation of spatial cognitive function in stroke-prone spontaneously hypertensive rats.

Neurovascular Protection by Telmisartan via Reducing Neuroinflammation in Stroke-Resistant Spontaneously Hypertensive Rat Brain after Ischemic Stroke

Telmisartan is a highly lipid-soluble angiotensin receptor blocker (ARB), which improves insulin sensitivity and reduces triglyceride levels and, thus, is called metabo-sartan. We examined the effects of telmisartan on neurovascular unit (N-acetylglucosamine oligomer [NAGO], collagen IV, and glial fibrillary acidic protein [GFAP]) and neuroinflammation (matrix metalloproteinase-9 [MMP-9] and inflammasome) in brain of stroke-resistant spontaneously hypertensive rat (SHR-SR). At 12 weeks of age, SHR-SR received transient middle cerebral artery occlusion (tMCAO) for 90 minutes and were divided into the following 3 groups, that is, vehicle group, low-dose telmisartan group (.3 mg/kg/d), and high-dose telmisartan group (3 mg/kg/d, postoral). Immunohistologic analysis at ages 6, 12, and 18 months showed progressive decreases of NAGO-positive endothelium and collagen IV-positive basement membrane and progressive increases of MMP-9-positive neurons, GFAP-positive astrocytes, and NLRP3-positive inflammasome in the cerebral cortex of vehicle group. Low-dose telmisartan reduced such changes without lowering blood pressure (BP), and high-dose telmisartan further improved such changes with lowering BP. The present findings suggest that a persistent hypertension caused a long-lasting inflammation after tMCAO in SHR-SR, which accelerated neurovascular disruption and emergent inflammasome, and that telmisartan greatly reduced such inflammation and protected the neurovascular unit via its pleiotropic effects in living hypertensive rat brain after ischemic stroke.

Protection against ischemic stroke damage by synergistic treatment with amlodipine plus atorvastatin in Zucker metabolic rat

Ischemic stroke is a major neurologic disorder and a leading cause of disability and death in the world. We compared neuroprotective effects of single or combination therapy of amlodipine (AM) and atorvastatin (AT) in such a metabolic syndrome model Zucker rat. The animals were pretreated with vehicle, AM, AT, or the combination of AM plus AT for 28days, and physical and serum parameters were analyzed, then 90min of transient middle cerebral artery occlusion (tMCAO), was performed followed by immunohistochemical analyses at 24h. Without affecting serum levels of lipids, adiponectin, and leptin, the combination therapy of AM plus AT ameliorated the post-ischemic brain weight increase. The single treatment with AM or AT itself exerted neuroprotective effects with reducing inductions of MMP-9 and AT2R, as well as with preserving collagen IV, and the combination therapy of AM plus AT showed a further synergistic benefit against acute ischemic neural damages. Single AT was more protective on these 3 molecules than single AM at this time point of 24h after tMCAO. Thus, the combination therapy with AM plus AT extended the neuroprotectives effect of single treatment with AM or AT on a part of neurovascular unit and a hypertension-related receptor.

Neurovascular protection of cilostazol in stroke-prone spontaneous hypertensive rats associated with angiogenesis and pericyte proliferation

Stroke is the major cause of death and decrease in the activities of daily living. This study sought to evaluate the effects of commonly used antiplatelet drugs on spontaneous cerebral infarction in relation to neurovascular protection associated with angiogenesis and pericyte proliferation. Stroke‐prone spontaneously hypertensive rats (SHR‐SP) were treated with vehicle, aspirin, clopidogrel, or cilostazol from 8 to 10 weeks of age. The interaction of neurovascular components among endothelial cells, pericytes, and astrocytic endfeet were immunohistochemically examined in brain sections. Angiogenesis associated with vascular endothelial growth factor receptor 2 (VEGFR2) and pericyte proliferation were also examined immunohistochemically. The expression and activity of matrix metalloproteinase 9 (MMP‐9) were assessed immunohistochemically and by gelatin zymography. Among the antiplatelet drugs, cilostazol preserved the neurovascular unit (NVU) by preventing astrocytic endfeet or pericytes from pathological detachment found in the vehicle and aspirin treatment. Cilostazol also inhibited the expression and activity of MMP‐9, which led to protection of the NVU. Furthermore, in the periinfarct area, cilostazol increased VEGFR2 expression, promoting angiogenesis through proliferation of pericytes. The present study showed a strong protection of NVU integrity by cilostazol and the promotion of angiogenesis by stimulating both endothelial VEGFR2 expression and pericyte proliferation. In addition to the antioxidative effect, these pleiotropic effects of cilostazol contribute to reduce spontaneous infarct volume and preserve motor and cognitive function in SHR‐SP.

Computerized Touch-panel Screening Tests for Detecting Mild Cognitive Impairment and Alzheimer's Disease

OBJECTIVE The increasing population of elderly people in Japan has accelerated the demand for a simple screening test to detect cognitive and affective declines in mild cognitive impairment (MCI) and the early stage of dementia. Methods We compared the cognitive and affective functions, activities of daily living (ADLs) and the results of four computerized touch-panel screening tests in 41 MCI subjects, 124 patients with Alzheimers disease (AD) and 75 age- and gender-matched normal controls. RESULTS All computerized touch-panel games were successfully used to discriminate the AD patients from the normal controls (** p<0.01). Although there were no differences in the findings of the conventional cognitive assessments, the results of the flipping cards game were significantly different (** p<0.01) between the normal controls (19.3 ± 9.5 sec) and MCI subjects (30.9 ± 18.4 sec). Three conventional affective assessments, the ADL score, Abes behavioral and psychological symptoms of dementia (ABS) (** p<0.01) and the apathy scale (AS) (* p<0.05), could be used to discriminate the MCI subjects (ABS, 0.9 ± 1.5; AS, 12.8 ± 5.9) from the normal controls (ABS, 0.1 ± 0.4; AS, 8.9 ± 5.3). CONCLUSION In the present study, all four touch-panel screening tests could be employed to discriminate AD patients from normal controls, whereas only the flipping cards game was effective for distinguishing MCI subjects from normal controls. Therefore, this novel touch-panel screening test may be a more sensitive tool for detecting MCI subjects among elderly patients.

Reducing Hemorrhagic Complication by Dabigatran Via Neurovascular Protection After Recanalization With Tissue Plasminogen Activator in Ischemic Stroke of Rat

This study assesses the risks and benefits of tissue plasminogen activator (tPA) treatment under oral anticoagulation with dabigatran compared with warfarin or vehicle control in transient middle cerebral artery occlusion (tMCAO). After pretreatment with warfarin (0.2 mg/kg/day), dabigatran (20 mg/kg/day), or vehicle (0.5% carboxymethyl cellulose sodium salt) for 7 days, tMCAO was induced for 120 min, followed by reperfusion and tPA (10 mg/kg/10 ml). Clinical parameters, including cerebral infarction volume, hemorrhagic volume, and blood coagulation, were examined. At 24 hr after reperfusion, markers for the neurovascular unit at the peri‐ischemic lesion were immunohistochemically examined in brain sections, and MMP‐9 activity was measured by zymography. Paraparesis and intracerebral hemorrhage volume were significantly improved in the dabigatran‐pretreated group compared with the warfarin‐pretreated group. A marked dissociation between astrocyte foot processes and the basal lamina or pericyte was observed in the warfarin‐pretreated group, which was greatly improved in the dabigatran‐pretreated group. Furthermore, a remarkable activation of MMP‐9 in the ipsilateral warfarin‐pretreated rat brain was greatly reduced in dabigatran‐pretreated rats. The present study reveals that the mechanism of intracerebral hemorrhage with warfarin‐pretreatment plus tPA in ischemic stroke rats is the dissociation of the neurovascular unit, including the pericyte. Neurovascular protection by dabigatran, which was first shown in this study, could partially explain the reduction in hemorrhagic complication by dabigatran reported from clinical study.

Anti-oxidative nutrient rich diet protects against acute ischemic brain damage in rats

We evaluated the neuroprotective effects of an anti-oxidative nutrient rich enteral diet (AO diet) that contained rich polyphenols (catechins and proanthocyanidins) and many other anti-oxidative ingredients. Wistar rats were treated with either vehicle, normal AO diet (containing 100kcal/100mL, catechin 38.75mg/100mL and proanthocyanidin 19mg/100mL, 1mL/day), or high AO diet (containing 10 times the polyphenols of the normal AO diet) for 14 days, and were subjected to 90min of transient middle cerebral artery occlusion. The AO diet improved motor function, reduced cerebral infarction volume, and decreased both peroxidative markers such as 4-hydroxynonenal, advanced glycation end products, 8-hydroxy-2-deoxyguanosine and inflammatory markers such as monocyte chemotactic protein-1, ionized calcium-binding adapter molecule-1, and tumor necrosis factor-α. Our study has shown that an AO diet has neuroprotective effects through both anti-oxidative and anti-inflammatory mechanisms, indicating that nutritional control with polyphenols could be useful for patients with acute ischemic stroke.

Simultaneous assessment of cognitive and affective functions in multiple system atrophy and cortical cerebellar atrophy in relation to computerized touch-panel screening tests

Cognitive impairment and affective dysfunction of multiple system atrophy (MSA) and cortical cerebellar atrophy (CCA) have not been simultaneously examined comparing standard test batteries and a sensitive tool to detect subtle cognitive decline in patients. In the present study, we simultaneously examined cognitive and affective ability in MSA with predominant cerebellar ataxia (MSA-C, n=25), MSA with predominant parkinsonism (MSA-P, n=8), and CCA (n=14) patients using computerized touch panel screening tests. Mini-mental state examination (MMSE), Hasegawa dementia scale-revised (HDS-R), frontal assessment battery (FAB), and Montreal cognitive assessment (MoCA) scores were significantly lower in MSA-C patients than in age-and gender-matched normal controls. One MSA-C patient showed a decrease in the regional cerebral blood flow (rCBF) of the frontal lobe. MSA-P patients showed no such cognitive decline. Only FAB and MoCA scores were significantly lower in the CCA patients. MSA and CCA patients also showed a mild to moderate depressive state. Touch-panel screening tests demonstrated a significant decline of beating devils game in all three disease groups including MSA-P patients, and a significant extension of the flipping cards game only in MSA-C patients. The present study demonstrated different cognitive and affective functions among MSA-C, MSA-P, and CCA patients, and a sensitive screening method for cognitive assessment using touch-panel tests.

Pericyte protection by edaravone after tissue plasminogen activator treatment in rat cerebral ischemia.

Pericytes play a pivotal role in contraction, mediating inflammation and regulation of blood flow in the brain. In this study, changes of pericytes in the neurovascular unit (NVU) were examined in relation to the effects of exogenous tissue plasminogen activator (tPA) and a free radical scavenger, edaravone. Immunohistochemistry and Western blot analyses showed that the overlap between platelet‐derived growth factor receptor β‐positive pericytes and N‐acetylglucosamine oligomers (NAGO)‐positive endothelial cells increased significantly at 4 days after 90 min of transient middle cerebral artery occlusion (tMCAO). The number of pericytes and the overlap with NAGO decreased with tPA but recovered with edaravone 4 days after tMCAO with proliferation. Thus, tPA treatment damaged pericytes, resulting in the detachment from astrocytes and a decrease in glial cell line‐derived neurotrophic factor secretion. However, treatment with edaravone greatly improved tPA‐induced damage to pericytes. The present study demonstrates that exogenous tPA strongly damages pericytes and destroys the integrity of the NVU, but edaravone treatment can greatly ameliorate such damage after acute cerebral ischemia in rats.