Effects of Edaravone on Nitric Oxide, Hydroxyl Radicals and Neuronal Nitric Oxide Synthase During Cerebral Ischemia and Reperfusion in Mice.

BACKGROUND: The purpose of this study was to investigate the effects of edaravone on nitric oxide (NO) production, hydroxyl radical (OH-) metabolism, and neuronal nitric oxide synthase (nNOS) expression during cerebral ischemia and reperfusion. METHODS: Edaravone (3 mg/kg) was administered intravenously to 14 C57BL/6 mice just before reperfusion. Eleven additional mice received saline (controls). NO production and OH- metabolism were continuously monitored using bilateral striatal in vivo microdialysis. OH- formation was monitored using the salicylate trapping method. Forebrain ischemia was produced in all mice by bilateral occlusion of the common carotid artery for 10 minutes. Levels of NO metabolites, nitrite (NO2-) and nitrate (NO3-), were determined using the Griess reaction. Brain sections were immunostained with an anti-nNOS antibody and the fractional area density of nNOS-immunoreactive pixels to total pixels determined. RESULTS: Blood pressure and regional cerebral blood flow were not significantly different between the edaravone and control groups. The levels of NO2- did not differ significantly between the 2 groups. The level of NO3- was significantly higher in the edaravone group compared with the control group after reperfusion. 2,3-dihydroxybenzoic acid levels were lower in the edaravone group compared with those in the control group after reperfusion. Immunohistochemistry showed nNOS expression in the edaravone group to be significantly lower than that in the control group 96 hours after reperfusion. CONCLUSIONS: These in vivo data indicate that edaravone may have a neuroprotective effect by reducing levels of OH- metabolites, increasing NO production and decreasing nNOS expression in brain cells.

Effect of Yokukansan on Nitric Oxide Production and Hydroxyl Radical Metabolism During Cerebral Ischemia and Reperfusion in Mice.

BACKGROUND: The purpose of this study was to investigate the effects of yokukansan on forebrain ischemia. Because we can measure nitric oxide production and hydroxyl radical metabolism continuously, we investigated the effect of yokukansan on nitric oxide production and hydroxyl radical metabolism in cerebral ischemia and reperfusion. METHODS: Yokukansan (300 mg per kg per day) was mixed into feed and given to 16 mice for 10days. Sixteen additional mice received normal feed (control). Nitric oxide production and hydroxyl radical metabolism were continuously monitored using the salicylate trapping method. Forebrain ischemia was producedin all mice by occluding the common carotid artery bilaterally for 10minutes. Levels of the nitric oxide metabolites nitrite and nitrate were determined using the Griess reaction. Survival rates of hippocampal CA1 neurons were calculated and 8-hydroxydeoxyguanosine-immunopositive cells were counted to evaluate the oxidative stress in hippocampal CA1 neurons 72hours after the start of reperfusion. RESULTS: Arterial blood pressure and regional cerebral blood flow were not significantly different between the 2 groups. The level of nitrate was significantly higher in the yokukansan group than in the control group during ischemia and reperfusion. Levels of 2,3- and 2,5-dihydroxybenzoic acid were significantly lower in the yokukansan group than in the control group during ischemia and reperfusion. Although survival rates in the CA1 did not differ significantly, there were fewer 8-hydroxydeoxyguanosine-immunopositive cells in animals that had received yokukansan than in control animals. CONCLUSIONS: These data suggest that yokukansan exerts reducing hydroxyl radicals in cerebral ischemic injury.

Effects of Memantine on Nitric Oxide Production and Hydroxyl Radical Metabolism during Cerebral Ischemia and Reperfusion in Mice.

BACKGROUND: The purpose of this study was to investigate the effects of memantine on brain ischemia. Because we can measure nitric oxide (NO) production and hydroxyl radical metabolism continuously, we investigated the effect of memantine on NO production and hydroxyl radical metabolism in cerebral ischemia and reperfusion. METHODS: Memantine (25 µmol/kg) was administered intraperitoneally to 6 C57BL/6 mice 30 minutes before ischemia. Seven additional mice received no injection (controls). NO production and hydroxyl radical metabolism were continuously monitored using bilateral striatal microdialysis in vivo. Hydroxyl radical formation was monitored using the salicylate trapping method. Forebrain ischemia was produced in all mice by occluding the common carotid artery bilaterally for 10 minutes. Levels of the NO metabolites nitrite (NO2-) and nitrate (NO3-) were determined using the Griess reaction. Survival rates of hippocampal CA1 neurons were calculated and 8-hydroxydeoxyguanosine (8-OHdG)-immunopositive cells were counted to evaluate the oxidative stress in hippocampal CA1 neurons 72 hours after the start of reperfusion. RESULTS: The regional cerebral blood flow was significantly higher in the memantine group than in the control group after reperfusion. Furthermore, the level of 2,3-dihydroxybenzoic acid was significantly lower in the memantine group than in the control group during ischemia and reperfusion. Levels of NO2- and NO3- did not differ significantly between the 2 groups. Although survival rates in the CA1 did not differ significantly, there were fewer 8-OHdG-immunopositive cells in animals that had received memantine than in control animals. CONCLUSIONS: These data suggest that memantine exerts partially neuroprotective effects against cerebral ischemic injury.

Evaluation of the Differences in the Effects of Antihypertensive Drugs on Blood Pressure Variability by 24-Hour Ambulatory Blood Pressure Monitoring in Chronic Cerebrovascular Disease.

BACKGROUND: It has been suggested that antihypertensive drug therapy is attributable to the lower blood pressure variability, we investigated the effects of 4 classes of antihypertensives on the blood pressure variability; in addition, we also compared the effects among 4 calcium channel blockers. METHODS: We measured the 24-hour blood pressure variability in 309 patients with a history of cerebrovascular disease treated with angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, ß blocker, or calcium channel blocker. RESULTS: The daytime blood pressure variability treated with ß blockers (14.3 ± 3.1) was higher than that treated with an angiotensin receptor blockers (11.5 ± 3.1) or calcium channel blockers (12.6 ± 3.4) in patients with cerebrovascular disease (P < .05). In the analysis of the patient distribution of blood pressure variability, patients receiving ß blockers occurred more frequently in the higher blood pressure variability (P = .0023). Treatment with angiotensin receptor blockers and cilnidipine, which blocks N-type calcium channels, was shown to be more frequently associated with the lower blood pressure variability (P = .0202 and .0467). The mean blood pressure of patients grouped by distribution of blood pressure variability was found to be independent to blood pressure variability, for any of the antihypertensive drugs or calcium channel blockers examined. CONCLUSIONS: From the results, it is suggested that angiotensin receptor blocker and calcium channel blockers rather than ß blockers may be more favorable for blood pressure management in patients with cerebrovascular disease. Among the calcium channel blockers, cilnidipine may be more favorable than other calcium channel blockers.

Glucosylceramide synthase activity and ceramide levels are modulated during cerebral ischemia after ischemic preconditioning.

After 24-hour middle cerebral artery occlusion (MCAO) in spontaneously hypertensive rats, brain ceramide level increased from baseline reached 595% (ischemic core) and 460% (perifocal/penumbral areas); brain glucosylceramide synthase (GCS) activities in these areas simultaneously decreased by 70% and 50%, respectively. Ten-minute MCAO preconditioning significantly attenuated 24-hour MCAO-induced ceramide accumulation by 40% to 60% in ischemic core and perifocal areas, and GCS activities improved by 60% to 70% in both areas. Thus, potentially toxic levels of brain ceramide induced by MCAO were attenuated to intermediate levels in preconditioned animals; brain GCS activity was relatively preserved. In ischemic tolerance, GCS appears to modulate otherwise high levels of brain ceramide.