n-tert-butyl-(2-sulfophenyl)nitrone and Brain-Ischemia

Hyperglycemia exacerbates focal ischemic brain damage supposedly through various mechanisms. One such mechanism is oxidative stress involving reactive oxygen and nitrogen species (RONS) production. Nitrones attenuate oxidative stress in various models of brain injury. Sodium 2-sulfophenyl-N-tert-butyl nitrone (S-PBN) can be administered experimentally and has been shown to be neuroprotective in experimental brain trauma.. We hypothesized that S-PBN might be neuroprotective in hyperglycemic focal cerebral ischemia.. Rats were made hyperglycemic by an intraperitoneal bolus injection of glucose (2 g/kg) and then subjected to 90 min transient middle cerebral artery occlusion (MCAO). They were randomized to a therapeutic regime of S-PBN (156 mg/kg) or saline given intravenously. Neurological testing according to Bederson and tetrazolium red staining were performed after 1 day.. S-PBN improved the neurological performance at day 1 both in Bederson score (1.3+/-0.8 versus 2.7+/-0.48) and on the inclined plane (74.5%+/-4.6 (S-PBN) versus 66%+/-8.3 (control), P<0.05) but did not reduce the infarct size. Physiological data did not differ between groups.. S-PBN may improve neurological performance at short-term survival (1 day) in the present model of hyperglycemic-ischemic brain injury in rats. This effect appeared not to be primarily related to reduced infarct size.

Topics: Animals; Benzenesulfonates; Brain Ischemia; Hyperglycemia; Male; Neuroprotective Agents; Rats; Rats, Sprague-Dawley

Oxygen free radical generation may have important secondary damaging effects after the onset of cerebral ischemia. Free radical scavengers have been used successfully in attenuating neuronal damage in the reperfusion period in transient forebrain ischemia. There are limited data on effectiveness in models of focal ischemia. Two free radical scavengers, alpha-phenyl-n-tert-butyl-nitrone (PBN) and N-tert-butyl-(2-sulfophenyl)-nitrone (S-PBN), have been shown to reduce oxidative-stress-induced neuronal injury. Whereas PBN has been demonstrated to reduce infarct volume in focal ischemia, neuroprotection has not been evaluated with S-PBN. The present study was designed to evaluate the neuroprotective effect of PBN and S-PBN compared to vehicle in a focal embolic middle cerebral artery (MCA) cerebral ischemia model in rats. Wistar rats were randomly divided into three groups (n = 10 each group). Animals in the control group received vehicle and those in the treatment groups were treated with PBN or S-PBN (both 100 mg/kg/day x 3 days, intraperitoneally) starting 2 h after the introduction of an autologous thrombus into the right-side MCA. The neurological outcome was observed and compared before and after treatment and between groups. The percentage of cerebral infarct volume was estimated from 2,3, 5-triphenyltetrazolium chloride stained coronal slices 72 h after the ischemic insult. Two-hour postischemia administration of PBN or S-PBN significantly improved neurobehavioral scores at 24 h following MCA embolization (both P < 0.01). The percentage of infarct volume for animals receiving vehicle was 32.8 +/- 9.4%. Two-hour delayed administration of PBN and S-PBN achieved a 35.4% reduction in infarct volume in treatment groups when compared with animals receiving vehicle (PBN vs control, 21.2 +/- 10.9% vs 32.8 +/- 9.4%; P < 0.05; S-PBN vs control, 21.2 +/- 13.1%, (P < 0.05). These data indicate that free radical generation may be involved in brain damage in this model and 2-h delayed postischemia treatment with PBN and S-PBN may have neuroprotective effects in focal cerebral ischemia. As S-PBN does not normally cross the blood-brain barrier, the neuroprotection evident in this study may be explained by entry into the brain via damaged vessels.

Topics: Animals; Benzenesulfonates; Brain; Brain Ischemia; Cyclic N-Oxides; Disease Models, Animal; Drug Administration Schedule; Free Radical Scavengers; Infarction, Middle Cerebral Artery; Injections, Intraperitoneal; Male; Neurologic Examination; Neuroprotective Agents; Nitrogen Oxides; Rats; Rats, Wistar; Recovery of Function; Thrombin

The relative roles of the superoxide and hydroxyl radicals in oxidative stress-induced neuronal damage were investigated using organotypic hippocampal slice cultures. Cultures exposed to 100 microM duroquinone, a superoxide-generating compound, for 3 h developed CA1-selective lesions over a period of 24 h. The damage accounted for approximately 64% of the CA1 subfield, whereas CA3 showed just 6% damage, a pattern of damage comparable to that observed following hypoxia/ischaemia. Duroquinone-induced damage was attenuated by a spin-trap agent. In contrast, hydroxyl radical-mediated damage, generated by exposure to 30 microM ferrous sulphate for 1 h, resulted in a CA3-dominant lesion. The damage developed over 24 h, similar to that observed with duroquinone, but with approximately 45% damage in CA3 compared with only 7% in CA1. These data demonstrate a selective vulnerability of the CA1 pyramidal neurones to superoxide-induced damage and suggest that of the free radicals generated following hypoxia/ischaemia, superoxide, rather than hydroxyl radical, is instrumental in producing neuronal damage.

Topics: Animals; Benzenesulfonates; Benzoquinones; Brain Ischemia; Cell Death; Ferrous Compounds; Hippocampus; Hydroxyl Radical; Hypoxia, Brain; Neurons; Organ Culture Techniques; Oxidative Stress; Rats; Rats, Wistar; Superoxides

The therapeutic time window for N-methyl-D-aspartate (NMDA) antagonists, non-NMDA antagonists, and glutamate release inhibitors in focal models of ischemia appears to be about 1-2 h. In contrast, a free radical spin trap was found to have an improved therapeutic window. We compared the therapeutic time windows of the NMDA antagonist dizolcilpine maleate (MK-801), the glutamate release inhibitor lamotrigine, and the free radical spin trap n-tert-butyl-alpha-(2-sulfophenyl)-nitrone (S-PBN) against striatal lesions produced by the mitochondrial toxin malonate, which produces histotoxic hypoxia. Lamotrigine exerted neuroprotective effects when administered at 1 h before malonate injections. MK-801 protected at 1 h before and 1 h after malonate injections, whereas S-PBN showed efficacy when administered up to 6 h after malonate injections. Striatal injections of malonate produced a rapid increase in lactate production and early changes in diffusion-weighted imaging as assessed by magnetic resonance imaging. Therefore, the time course to evolve a lesion in our model of histotoxic hypoxia is comparable with that of other models of focal ischemia. These findings provide direct evidence that a free radical spin trap has an improved therapeutic window compared to an NMDA antagonist and a glutamate release inhibitor. This could be a therapeutic advantage in the treatment of clinical stroke patients.

Topics: Animals; Benzenesulfonates; Brain Ischemia; Corpus Striatum; Dizocilpine Maleate; Dose-Response Relationship, Drug; Free Radicals; Lamotrigine; Magnetic Resonance Imaging; Male; Malonates; Oxygen; Rats; Rats, Sprague-Dawley; Spin Trapping; Time Factors; Triazines