MCI-186 reduces oxidative cellular damage and increases DNA repair function in the rabbit spinal cord after transient ischemia

Oxidative DNA Damage in the Pathophysiology of Spinal Cord Injury: Seems Obvious, but Where Is the Evidence?

Oxidative stress occurs at various phases of spinal cord injury (SCI), promoting detrimental processes such as free radical injury of proteins, nucleic acids, lipids, cytoskeleton, and organelles. Oxidative DNA damage is likely a major contributor to the pathogenesis of SCI, as a damaged genome cannot be simply turned over to avert detrimental molecular and cellular outcomes, most notably cell death. Surprisingly, the evidence to support this hypothesis is limited. There is some evidence that oxidative DNA damage is increased following SCI, mainly using comet assays and immunohistochemistry. However, there is great variability in the timing and magnitude of its appearance, likely due to differences in experimental models, measurement techniques, and the rigor of the approach. Evidence indicates that 8-oxodG is most abundant at 1 and 7 days post-injury (dpi), while DNA strand breaks peak at 7 and 28 dpi. The DNA damage response seems to be characterized by upregulation of PCNA and PARP1 but downregulation of APEX1. Significant improvements in the analysis of oxidative DNA damage and repair after SCI, including single-cell analysis at time points representative for each phase post-injury using new methodologies and better reporting, will uncover the role of DNA damage and repair in SCI.

Drug Repurposing: Promises of Edaravone Target Drug in Traumatic Brain Injury

Edaravone is a potent free-radical scavenger that has been in the market for more than 30 years. It was originally developed in Japan to treat strokes and has been used there since 2001. Aside from its anti-oxidative effects, edaravone demonstrated beneficial effects on proinflammatory responses, nitric oxide production, and apoptotic cell death. Interestingly, edaravone has shown neuroprotective effects in several animal models of diseases other than stroke. In particular, edaravone administration was found to be effective in halting amyotrophic lateral sclerosis (ALS) progression during the early stages. Accordingly, after its success in Phase III clinical studies, edaravone has been approved by the FDA as a treatment for ALS patients. Considering its promises in neurological disorders and its safety in patients, edaravone is a drug of interest that can be repurposed for traumatic brain injury (TBI) treatment. Drug repurposing is a novel approach in drug development that identifies drugs for purposes other than their original indication. This review presents the biochemical properties of edaravone along with its effects on several neurological disorders in the hope that it can be adopted for treating TBI patients.

DNA damage accumulates and responses are engaged in human ALS brain and spinal motor neurons and DNA repair is activatable in iPSC-derived motor neurons with SOD1 mutations

DNA damage is implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). However, relationships between DNA damage accumulation, DNA damage response (DDR), and upper and lower motor neuron vulnerability in human ALS are unclear; furthermore, it is unknown whether epigenetic silencing of DNA repair pathways contributes to ALS pathogenesis. We tested the hypotheses that DNA damage accumulates in ALS motor neurons along with diminished DDR, and that DNA repair genes undergo hypermethylation. Human postmortem CNS tissue was obtained from ALS cases (N = 34) and age-matched controls without neurologic disease (N = 15). Compared to age-matched controls, abasic sites accumulated in genomic DNA of ALS motor cortex and laser capture microdissection-acquired spinal motor neurons but not in motor neuron mitochondrial DNA. By immunohistochemistry, DNA damage accumulated significantly in upper and lower motor neurons in ALS cases as single-stranded DNA and 8-hydroxy-deoxyguanosine (OHdG) compared to age-matched controls. Significant DDR was engaged in ALS motor neurons as evidenced by accumulation of c-Abl, nuclear BRCA1, and ATM activation. DNA damage and DDR were present in motor neurons at pre-attritional stages and throughout the somatodendritic attritional stages of neurodegeneration. Motor neurons with DNA damage were also positive for activated p53 and cleaved caspase-3. Gene-specific promoter DNA methylation pyrosequencing identified the DNA repair genes Ogg1, Apex1, Pnkp and Aptx as hypomethylated in ALS. In human induced-pluripotent stem cell (iPSC)-derived motor neurons with familial ALS SOD1 mutations, DNA repair capacity was similar to isogenic control motor neurons. Our results show that vulnerable neurons in human ALS accumulate DNA damage, and contrary to our hypothesis, strongly activate and mobilize response effectors and DNA repair genes. This DDR in ALS motor neurons involves recruitment of c-Abl and BRCA1 to the nucleus in vivo, and repair of DNA double-strand breaks in human ALS motor neurons with SOD1 mutations in cell culture.

Population Difference in the Associations of KLOTH Promoter Methylation with Mild Cognitive Impairment in Xinjiang Uygur and Han Populations

Background

Mild cognitive impairment (MCI) is the intermediate stage of the cognitive changes between normal aging and dementia. KLOTH is an age-related gene that may contribute to the risk of MCI. The aim of our study was to explore the association between KLOTHO promoter methylation and MCI in Xinjiang Uygur and Han populations.

Methods

DNA methylation assay was performed using the bisulphite pyrosequencing technology among 96 Uygur (48 MCI and 48 controls) and 96 Han (48 MCI and 48 controls) Chinese individuals from Xinjiang province of China.

Results

We found significant association between KLOTHO promoter methylation and MCI in the Han Chinese (CpG1: p = 3.77E-06; CpG2: p = 1.91E-07; CpG3: p = 5.83E-07; CpG4: p = 2.23E-05; CpG5: p = 3.03E-06) but not in the Uygur Chinese. Higher KLOTHO promoter methylation levels were found in Han MCI patients than Uygur MCI patients for all the five CpGs (adjusted p values by age < 0.02).

Conclusion

Our results showed that KLOTHO promoter hypermethylation contributed to the MCI risk in Xinjiang Han Chinese but not in Xinjiang Uygur Chinese. The population difference of KLOTHO methylation in the risk of MCI required further investigation in the future.

Effect of coenzyme Q10 on spinal cord ischemia-reperfusion injury

OBJECT

Spinal cord ischemia remains a serious complication of thoracoabdominal aortic aneurysm surgery. Coenzyme Q10, a potent antioxidant, has been reported to exert a neuroprotective effect. In the present study, we evaluated the effect of coenzyme Q10 pretreatment on spinal cord ischemia-reperfusion injury.

METHODS

Male Sprague-Dawley rats were treated with either 300 mg/kg coenzyme Q10 (CoQ10 group, n = 12) or saline (control and sham groups, n = 12 for each group) for 5 days before ischemia. Spinal cord ischemia was induced in the control and CoQ10 groups. Neurological function was assessed using the Basso-Beattie-Bresnahan (BBB) motor rating scale until 7 days after reperfusion, and then the spinal cord was harvested for histopathological examinations and an evaluation of malondialdehyde level.

RESULTS

On post-reperfusion Day 1, the CoQ10 group showed higher BBB scores compared with those in the control group, although the difference was not significant. However, on Day 2, the CoQ10 group showed a significantly higher BBB score than the control group (14.0 [10.3–15.0] vs 8.0 [5.0–9.8], median [IQR], respectively; p = 0.021), and this trend was maintained until Day 7 (17.5 [16.0–18.0] vs 9.0 [6.5–12.8], respectively; p < 0.001). Compared with the control group, the CoQ10 group had more normal motor neurons (p = 0.003), fewer apoptotic changes (p = 0.003) and a lower level of tissue malondialdehyde (p = 0.024).

CONCLUSIONS

Pretreatment with 300 mg/kg coenzyme Q10 resulted in significantly improved neurological function and preservation of more normal motor neurons.

Edaravone's free radical scavenging mechanisms of neuroprotection against cerebral ischemia: review of the literature

Free radicals and oxidative stress play key roles in cerebral ischemic pathogenesis and represent pharmacological targets for treatment. Edaravone (Edv), one of antioxidant agents that have been used in acute ischemic stroke in both clinical settings and animal experiments, exerts neuroprotective effect on ischemic injured brains. This review is aimed to elaborate the latest molecular mechanisms of the neuroprotection of Edv on cerebral ischemia and provide reasonable evidence in its clinical application. It is found that Edv has neuroprotective influence on cerebral ischemia, which is closely related to the facets of scavenging reactive oxygen species (ROS), hydroxyl radical (ċOH) and reactive nitrogen species (RNS). And it is a good antioxidant agent that can be safely used in the treatment of cerebral ischemia and chronic neurodegenerative disorders as well as other ischemia/reperfusion (I/R)-related diseases. The combination of Edv with thrombolytic therapy also can be applied in clinical settings and will be greatly beneficial to patients with stroke.

Oxidative stress, DNA damage, and the telomeric complex as therapeutic targets in acute neurodegeneration

Oxidative stress has been identified as an important contributor to neurodegeneration associated with acute CNS injuries and diseases such as spinal cord injury (SCI), traumatic brain injury (TBI), and ischemic stroke. In this review, we briefly detail the damaging effects of oxidative stress (lipid peroxidation, protein oxidation, etc.) with a particular emphasis on DNA damage. Evidence for DNA damage in acute CNS injuries is presented along with its downstream effects on neuronal viability. In particular, unchecked oxidative DNA damage initiates a series of signaling events (e.g. activation of p53 and PARP-1, cell cycle re-activation) which have been shown to promote neuronal loss following CNS injury. These findings suggest that preventing DNA damage might be an effective way to promote neuronal survival and enhance neurological recovery in these conditions. Finally, we identify the telomere and telomere-associated proteins (e.g. telomerase) as novel therapeutic targets in the treatment of neurodegeneration due to their ability to modulate the neuronal response to both oxidative stress and DNA damage.

Potential of edaravone for neuroprotection in neurologic diseases that do not involve cerebral infarction

Edaravone was originally developed as a potent free radical scavenger and has been widely used to treat cerebral infarction in Japan since 2001. Several free radical scavengers have been developed and some of them have progressed to clinical trials for the treatment of cerebral infarction. One such scavenger, edaravone, has been approved by the regulatory authority in Japan for the treatment of patients with cerebral infarction. Of particular interest is the ability of edaravone to diffuse into the central nervous system in various neurologic diseases. Aside from its hydroxyl radical scavenging effect, edaravone has been found to have beneficial effects on inflammation, matrix metalloproteinases, nitric oxide production and apoptotic cell death. Concordantly, edaravone has been found to have neuroprotective effects in a number of animal models of disease, including stroke, spinal cord injury, traumatic brain injury, neurodegenerative diseases and brain tumors. The proven safety of edaravone following 9 years of use as a free radical scavenger suggests that it may have potential for development into an effective treatment of multiple neurologic conditions in humans.

Protective effects of edaravone on experimental spinal cord injury in rats

BACKGROUND

Spinal cord injury (SCI) is a leading cause of morbidity and mortality among youth and adults. Secondary injury mechanisms within the spinal cord (SC) are well known to cause deterioration after an acute impact. Free radical scavengers are among the most studied agents in animal models of SCI. Edaravone is a scavenger of hydroxyl radicals.

METHODS

We aimed to measure and compare the effects of both methylprednisolone and edaravone on tissue and on serum concentrations of nitric oxide (NO), malondialdehyde (MDA) levels, superoxide dismutase (SOD) activity, glutathione peroxidase (GSH-Px) activity, and tissue total antioxidant capacity (TAC) in rats with SCI. SCI was induced in four groups of Wistar albino rats by a weight-drop method. The neurological function of the rats was periodically tested. At the end of the experiment, blood samples were collected, and SC tissue samples were harvested for biochemical evaluation.

RESULTS

The tissue level of NO was decreased in the edaravone-treated group compared with the no-treatment group (p < 0.05). The tissue levels of SOD and GSH-Px were higher in the edaravone-treated group than in the no-treatment group (p < 0.05). The serum levels of NO were lower in the edaravone-treated and methylprednisolone-treated groups than in the no-treatment group (p < 0.05). The serum levels of SOD in the edaravone-treated group did not differ from those of any other group. The serum levels of MDA in the edaravone-treated and no-treatment groups were higher than in the two other groups (p < 0.05). Tissue levels of MDA in the edaravone-treated group were lower than in the no-treatment group (p < 0.05). Tissue levels of TAC in the edaravone-treated group were higher than in the no-treatment and methylprednisolone-treated groups (p < 0.05). The neurological outcome scores of the animals in treatment groups did not depict any statistically significant improvement in motor functions. However, edaravone seemed to prevent further worsening of the immediate post-SCI neurological status.

CONCLUSION

Our biochemical analyses indicate that edaravone is capable of blunting the increased oxidative stress that follows SCI. We show, for the first time, that edaravone enhances the TAC in SC tissue. This beneficial effect of edaravone on antioxidant status may act to minimize the secondary neurological damage that occurs during the acute phase after SCI.

Hyperglycemia magnifies Schwann cell dysfunction and cell death triggered by PA-induced lipotoxicity

Lipid overload resulting in lipotoxicity is prominent in a number of chronic diseases and has been associated with cellular dysfunction and cell death. This study characterizes palmitic acid-induced lipotoxicity (PA-LTx) in Schwann cell cultures grown in normal and high glucose concentrations. The study shows for the first time that Schwann cell (SC) cultures exposed to elevated levels of PA exhibit a dose- and time-dependent loss in cell viability. Hoescht and Annexin V/7AAD staining confirmed cell death through apoptosis and the lipotoxic effect was more dramatic in SC cultures grown under high glucose conditions. The first indication of cellular dysfunction in treated SC cultures was a decrease in Ca(++) levels in the endoplasmic reticulum (ER, [Ca(++)](ER)) observed five minutes following the initial challenge with PA. This decrease in [Ca(++) ](ER) was followed by a significant increase in the expression of ER stress signature genes CHOP, Xbp1 and GRP78. The early ER stress response induced by PA-LTx was followed by a strong mitochondrial membrane depolarization. Flow cytometry using 2', 7'-dichlorodihydrofluorescein diacetate (H(2)DCFDA) showed an increase in oxidative stress within three to six hours after PA treatment. Treatment of cultures undergoing PA-LTx with the calcium chelator BAPTA-AM and the anti-oxidant MCI-186 significantly reversed the lipotoxic effect by decreasing the generation of ROS and significantly increasing cell viability. We conclude that lipotoxicity in Schwann cells results in cellular dysfunction and cell death that involves a robust ER stress response, mitochondrial dysfunction and an augmented state of cellular oxidative stress (ASCOS).

Changes of expression of glucose transporters in the fetal lamb brain after MCI-186 administration to the maternal circulation with 10-min persistent umbilical cord occlusion

OBJECTIVE

To evaluate the effect of MCI-186 (3-methyl-1-phenyl-2-pyrazoline-5-one), a potent hydroxyl radical scavenger, administered to the maternal circulation following umbilical cord occlusion in regard to glucose transporter (GLUT) expression.

MATERIALS AND METHODS

Fourteen instrumented lambs were prepared. In three cases, a 10-min persistent umbilical cord occlusion was performed; 30 min after the insult, fetal brains were extirpated (Group A). Four cases had a 10-min occlusion(Group B) and four cases had 10-min occlusion and were administered MCI-186 to the maternal circulation (Group C).Three days following the insult, the fetal brains were extirpated. The remaining three cases had a sham operation (Group D).Brain tissue sections were stained at the locations of GLUT-1, -3 and -5 and were evaluated by two pathologists.

RESULTS

The expression of GLUT-1 and -3 significantly increased in the basal ganglia, hippocampi and periventricular region of Group B when compared with that of Group A. The expression of GLUT-1 and -3 in three regions of Group B were significantly higher than that of Group C and D. GLUT-5 was recognised only in Group B.

CONCLUSION

On the basis of expression of GLUT, the protective effect of MCI-186 on brain injury resulting from hypoxia/ ischemia-reperfusion is documented.

MCI-186 administered to the maternal circulation inhibits fetal brain injury resulting from total umbilical cord occlusion in the chronically instrumented fetal lamb

OBJECTIVE

To evaluate the transplacental effects of MCI-186 (edaravone), a potent hydroxyl radical scavenger, administered to the maternal circulation to inhibit fetal brain injury caused by umbilical cord occlusion.

METHODS

Nine chronically instrumented lambs were prepared. In three cases, 10-min persistent total umbilical cord occlusion (group A) was performed. Another three cases underwent occlusion and were administered 60 mg of MCI-186 through the maternal femoral vein prior to the end of occlusion (group B). The remaining three cases underwent sham operation (group C). On day 3 after insult, fetal brains were extirpated. Paraffin-embedded brain tissue sections were stained with hematoxylin and eosin, Bodian, Kluver-Barrera, and TUNEL. Neuronal cellular damage was evaluated by two pathologists blinded to the experimental conditions.

RESULTS

Group A displayed numerous cells with eosinophilic condensation of nuclear chromatin and proliferation of microglia in the hippocampus and basal ganglia. TUNEL-positive cells were observed in the periventricular area. Group B showed microglial proliferations, but no marked changes. No pathological changes were apparent in group C.

CONCLUSIONS

MCI-186 administered to the maternal circulation could inhibit fetal brain injury resulting from hypoxia-reperfusion induced by umbilical cord occlusion.

Edaravone for the treatment of acute cerebral infarction: role of endothelium-derived nitric oxide and oxidative stress

Thrombolytic therapy is the most effective therapeutic strategy for the prevention of brain injury and reduction of mortality in patients with acute cerebral infarction. A combination of established thrombolytic therapy and effective neuronal protection therapy has more beneficial effects for patients with acute cerebral infarction. Edaravone (chemical name: 3-methyl-1-phenyl-2-pyrazolin-5-one) is a strong, novel scavenger of free radicals. Several lines of evidence have shown that edaravone has preventive effects on brain injury following ischaemia and reperfusion in patients with brain attack. This review focuses on putative mechanisms underlying the beneficial effects of edaravone on the atherosclerotic process in patients with stroke and on the possibility of edaravone-induced extension of the therapeutic time window in patients with acute cerebral infarction.

The novel antioxidant edaravone: from bench to bedside

Over the last decade, important advances have been made to support the fact that reactive oxygen species (ROS) are generated and play a harmful role during the acute and late stages of cerebral ischemia. Several drugs, such as radical scavengers and antioxidants, have been evaluated in preclinical and clinical studies. Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one; Radicut, Mitsubishi Tanabe Pharma Corporation) is a novel antioxidant that is currently used in Japan for the treatment of patients in the acute stage of cerebral infarction. Edaravone scavenges ROS and inhibits proinflammatory responses after brain ischemia in animals and humans. In particular, postischemic inflammation, leading to brain edema and infarction due to neuronal damage and endothelial cell death, can be ameliorated by edaravone. In addition to these antistroke effects, edaravone has also been shown to prevent oxidative damage to various extracerebral organs. Therefore, in addition to its usefulness in the treatment of stroke, edaravone is expected to play an integral role in the treatment of many oxidative stress-related diseases.

Neuroprotective effects of edaravone-administration on 6-OHDA-treated dopaminergic neurons

Background

Parkinson's disease (PD) is a neurological disorder characterized by the degeneration of nigrostriatal dopaminergic systems. Free radicals induced by oxidative stress are involved in the mechanisms of cell death in PD. This study clarifies the neuroprotective effects of edaravone (MCI-186, 3-methyl-1-phenyl-2-pyrazolin-5-one), which has already been used for the treatment of cerebral ischemia in Japan, on TH-positive dopaminergic neurons using PD model both in vitro and in vivo. 6-hydroxydopamine (6-OHDA), a neurotoxin for dopaminergic neurons, was added to cultured dopaminergic neurons derived from murine embryonal ventral mesencephalon with subsequet administration of edaravone or saline. The number of surviving TH-positive neurons and the degree of cell damage induced by free radicals were analyzed. In parallel, edaravone or saline was intravenously administered for PD model of rats receiving intrastriatal 6-OHDA lesion with subsequent behavioral and histological analyses.

Results

In vitro study showed that edaravone significantly ameliorated the survival of TH-positive neurons in a dose-responsive manner. The number of apoptotic cells and HEt-positive cells significantly decreased, thus indicating that the neuroprotective effects of edaravone might be mediated by anti-apoptotic effects through the suppression of free radicals by edaravone. In vivo study demonstrated that edaravone-administration at 30 minutes after 6-OHDA lesion reduced the number of amphetamine-induced rotations significantly than edaravone-administration at 24 hours. Tyrosine hydroxylase (TH) staining of the striatum and substantia nigra pars compacta revealed that edaravone might exert neuroprotective effects on nigrostriatal dopaminergic systems. The neuroprotective effects were prominent when edaravone was administered early and in high concentration. TUNEL, HEt and Iba-1 staining in vivo might demonstrate the involvement of anti-apoptotic, anti-oxidative and anti-inflammatory effects of edaravone-administration.

Conclusion

Edaravone exerts neuroprotective effects on PD model both in vitro and in vivo. The underlying mechanisms might be involved in the anti-apoptotic effects, anti-oxidative effects, and/or anti-inflammatory effects of edaravone. Edaravone might be a hopeful therapeutic option for PD, although the high therapeutic dosage remains to be solved for the clinical application.

The adverse effect of back-bleeding from lumbar arteries on spinal cord pathophysiology in a rabbit model

OBJECTIVE

The purpose of this study was to evaluate the adverse effect of back-bleeding from the lumbar arteries on spinal cord pathophysiology in a rabbit model.

METHODS

White rabbits were divided into 3 groups. Through laparotomy, the abdominal aorta was clamped below the renal artery and above the aortic bifurcation for 15 minutes. In group 1 (n = 13), back-bleeding from the lumbar arteries was drained from the aorta during aortic clamping. In group 2 (n = 10), back-bleeding was not drained. Group 3 (n = 6) was the sham-operated group. Postoperative hind limb function was evaluated using the modified Tarlov scale, and cell damage was analyzed by counting the number of intact motor neurons and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive neurons.

RESULTS

At 4 hours after operation, all animals were neurologically impaired in group 1 and normal in group 2. Motor neurons were significantly damaged in group 1 compared with groups 2 and 3 (P < .05). Forty-eight hours later, almost all animals were neurologically and pathologically damaged in groups 1 and 2. There was no difference in the number of normal motor neurons between the two groups, but the number of TUNEL-positive cells in group 2 was significantly larger than those in group 1.

CONCLUSIONS

Rabbits with 15-minute aortic clamping in the infrarenal portion showed delayed paraplegia, and those with back-bleeding from lumbar arteries showed early onset of paraplegia. The prevention of back-bleeding from intercostal arteries and lumbar arteries during thoracoabdominal aortic surgery was considered to reduce spinal ischemic injury.

Controlled low-pressure perfusion at the beginning of reperfusion attenuates neurologic injury after spinal cord ischemia

OBJECTIVE

Paraplegia caused by spinal cord ischemia remains a serious complication after surgical repair of thoracoabdominal aortic aneurysms. This study tests the hypothesis that controlled low-pressure perfusion at the beginning of reperfusion can attenuate neurologic injury of the spinal cord after transient ischemia.

METHODS

Spinal cord ischemia was accomplished in rabbits by occlusion of the infrarenal aorta with a balloon catheter for 25 minutes. In the normal reperfusion group, reperfusion was completely restored immediately after ischemia, whereas perfusion pressure was controlled between 45 and 55 mm Hg during the first 10 minutes followed by complete reperfusion in the low-pressure reperfusion group. Functional evaluation with the Tarlov score during a 14-day observation period, histopathologic assessment of the lumbar spinal cord, and measurements of malondialdehyde levels and amyloid precursor protein immunoreactivity were performed.

RESULTS

Neurologic impairment was remarkably attenuated in the low-pressure reperfusion group (compared with the Tarlov scores of the normal reperfusion group, P < .05 at day 2; P < .01 at days 1, 7, and 14). Compared with the normal reperfusion group, malondialdehyde levels were significantly lower in the low-pressure reperfusion group (P < .05), and the large motor neurons of the low-pressure reperfusion group were preserved to a much greater extent (P < .05). White matter injury of the low-pressure reperfusion group was also markedly attenuated as evidenced by reduction of vacuolation area of the white matter (P < .05) and decrease of the amyloid precursor protein immunoreactivity (P < .05).

CONCLUSION

Reperfusion initiated with low-pressure perfusion exerts neuroprotective effects on the spinal cord against ischemia/reperfusion injury.

The production of hydroxyl radicals in the fetal lamb brain resulting from occlusion of the umbilical circulation and the transplacental effect of MCI-186 to inhibit hydroxyl radical production

The present study evaluated hydroxyl radical production in fetal lamb brain during and after umbilical cord occlusion and examined the effects of injecting MCI-186 (3-metyl-1-phenyl-2-pyrazolin-5-one; Edaravone), a hydroxyl radical scavenger, into the maternal circulation. In 11 chronically instrumented lambs, intermittent total umbilical cord occlusions 1 min out of every 3 min for 1 h and 10-min persistent total umbilical cord occlusion were performed with brain microdialysis using 5 mM of sodium salicylate. In the remaining four lambs, 60 mg of MCI-186 was administered into the maternal circulation from shortly before the end of 10-min persistent total umbilical cord occlusion. Concentrations of 2,3-dihydroxy-benzoic acid (2,3-DHBA), produced by hydroxyl radical reactions with sodium salicylate, were measured in perfusate by HPLC. Concentration of 2,3-DHBA in perfusate was 23.05 +/- 10.95 nM before umbilical cord occlusion. Levels of 2,3-DHBA tended to increase slightly during and after intermittent umbilical cord occlusion, and were significantly increased by the end of 10-min occlusion (40.06 +/- 21.36 nM) and after occlusion (93.74 +/- 29.17 nM). Infusion of MCI-186 suppressed 2,3-DHBA concentration to 29.35 +/- 14.95 nM after occlusion. Administration of MCI-186 into the maternal circulation reduces hydroxyl radical production induced by umbilical cord occlusion in the fetal lamb brain.