The Effect of Aging on Nitric Oxide Production during Cerebral Ischemia and Reperfusion in Wistar Rats and Spontaneous Hypertensive Rats: An In Vivo Microdialysis Study.

Nitric oxide (NO) is involved in the pathogenesis of cerebral ischemic injury. Here, we investigated the effects of aging on NO production during cerebral ischemia-reperfusion (IR). Male Wister rats (WRs) were assigned to 12-month-old (older; n = 5) and 3-month-old (younger; n = 7) groups. Similarly, male spontaneous hypertensive rats (SHRs) were allocated to 12-month-old (older; n = 6) and 3-month-old (younger; n = 8) groups. After anesthesia, their NO production was monitored using in vivo microdialysis probes inserted into the left striatum and hippocampus. Forebrain cerebral IR injuries were produced via ligation of the bilateral common carotid arteries, followed by reperfusion. The change in the NO3- of the older rats in the SHR groups in the striatum was less compared to that of the younger rats before ischemia, during ischemia, and after reperfusion (p < 0.05). In the hippocampus, the change in the NO3- of the older rats in the SHR groups was lower compared to that of the younger rats after reperfusion (p < 0.05). There were no significant differences between the two WR groups. Our findings suggested that aging in SHRs affected NO production, especially in the striatum, before and during cerebral ischemia, and after reperfusion. Hypertension and aging may be important factors impacting NO production in brain IR injury.

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.

[Anti-Ma2, anti-NMDA-receptor and anti-GluRε2 limbic encephalitis with testicular seminoma: short-term memory disturbance].

A 36-year-old man presented with cognitive impairment and disturbance of short-term memory functions with character change. Cerebrospinal fluid analysis revealed no abnormalities; however, brain MRI revealed high-signal intensity from bilateral hippocampus lesions on fluid attenuated inversion recovery (FLAIR) images and T(2) weighted images. The 18F-fluorodeoxyglucose PET demonstrated high glucose uptake in the bilateral hippocampus lesions. He was diagnosed as limbic encephalitis, and was administered high-dose intravenous methylprednisolone and immune adsorption plasma therapy followed by intravenous immunoglobulin therapy. MRI abnormalities improved after treatment but recent memory disturbance remained. Ma2 antibody, NMDA-receptor antibody, and GluRε2 antibody were positive. Eleven months atter the onset of disease, the tumor was identified in left testicle by ultrasound and removed the tumor. The pathological findings were seminoma. We experienced a case of paraneoplastic limbic encephalitis associated with seminoma with short-term memory disturbance. The occurrence of paraneoplastic limbic encephalitis with antibodies against cell membrane (NMDA-receptor antibody and GluRε2 antibody) and intracellular (Ma2 antibody) is rare even in the literature.

Nitric oxide production during cerebral ischemia and reperfusion in eNOS- and nNOS-knockout mice.

The purpose of this study was to clarify the kinetics of nitric oxide (NO) induced by either endothelial NO synthase (eNOS) or neuronal NO synthase (nNOS) after transient global forebrain ischemia. We investigated NO production and ischemic changes to hippocampal CA1 neurons in eNOS knockout (-/-) mice and nNOS (-/-) mice during cerebral ischemia and reperfusion. NO production was continuously monitored by in vivo microdialysis. Global forebrain ischemia was produced by occlusion of both common carotid arteries for 10 minutes. Levels of nitrite (NO(2)(-)) and nitrate (NO(3)(-)), as NO metabolites, in dialysate were determined using the Griess reaction. Two hours after the start of reperfusion, animals were perfused with 4% paraformaldehyde. Hippocampal CA1 neurons were divided into three phases (severely ischemic, moderately ischemic, surviving), and the ratio of surviving neurons to degenerated neurons was calculated as the survival rate. The relative cerebral blood flow (rCBF) was significantly higher in nNOS (-/-) mice than in control mice after reperfusion. Levels of NO(3)(-) were significantly lower in eNOS (-/-) mice and nNOS (-/-) mice than in control mice during ischemia and reperfusion. NO(3)(-) levels were significantly lower in nNOS (-/-) mice than in eNOS (-/-) mice after the start of reperfusion. Survival rate tended to be higher in nNOS (-/-) mice than in control mice, but not significantly. These in vivo data suggest that NO production in the striatum after reperfusion is closely related to activities of both nNOS and eNOS, and is mainly related to nNOS following reperfusion.

[A case of amyotrophic lateral sclerosis with SIADH and throbbing headache induced by selective serotonin reuptake inhibitor].

A 57-year-old man with amyotrophic lateral sclerosis (ALS) was admitted because of depressive state. Selective serotonin reuptake inhibitor (SSRI), an antidepressant, was started on the admission day. The throbbing headache in the right temporal region appeared on day 3, and an analgesic drug was not completely effective. Serum sodium value on admission was 131 mEq/l. After SSRI was started the hyponatremia rapidly progressed, and it became 112 mEq/l on day 4. SSRI was discontinued, and headache disappeared; serum sodium was improved to 129 mEq/l. It has been reported that syndrome of inappropriate secretion of antidiuretic hormone (SIADH) may be associated with ALS. We consider that subclinical SIADH was manifested by SSRI in this case. SSRI seems to be a cause of headache, since headache disappeared completely by discontinuation of SSRI.