No abstract

The Fas pathway and oxidative stress mediate neuronal death in stroke and may contribute to neurodegenerative disease. We tested the hypothesis that these two factors synergistically produce spinal motor neuron degeneration in amyotrophic lateral sclerosis (ALS

Excitotoxicity and oxidative stress mediate neuronal death after hypoxic-ischemic brain injury. We examined the possibility that targeting both N-methyl-D-aspartate (NMDA) receptor-mediated excitotoxicity and oxidative stress would result in enhanced neuroprotection against hypoxicischemia. 2-Hydroxy-5-(2,3,5,6-tetrafluoro-4-trifluoromethyl-benzylamino)-benzoic acid (Neu2000) was derived from aspirin and sulfasalazine to prevent both NMDA neurotoxicity and oxidative stress. In cortical cell cultures, Neu2000 was shown to be an uncompetitive NMDA receptor antagonist and completely blocked free radical toxicity at doses as low as 0.3 lmol/L. Neu2000 showed marked neuroprotection in a masked fashion using histology and behavioral testing in two rodent models of focal cerebral ischemia without causing neurotoxic side effects. Neu2000 protected against the effects of middle cerebral artery occlusion, even when delivered 8 h after reperfusion. Single bolus administration of the drug prevented gray and white matter degeneration and spared neurologic function for over 28 days after MACO. Neu2000 may be a novel therapy for combating both NMDA receptor-mediated excitotoxicity and oxidative stress, the two major routes of neuronal death in ischemia, offering profound neuroprotection and an extended therapeutic window.

Excess activation of ionotropic glutamate receptors, primarily N-methyl-D-aspartate (NMDA) receptors and free radicals, evoke nerve cell death following hypoxic-ischemic brain injury in various animal models. However, clinical trials in stroke patients using NMDA receptor antagonists have failed to show efficacy primarily due to the limited therapeutic time window for neuroprotection and a narrow therapeutic index. In comparison, antioxidants prolonged the time window for neuroprotection in animal models of ischemic stroke and showed greater therapeutic potential in clinical trials for ischemic stroke. Excess activation of NMDA receptors and free radicals mediate the two separate pathways of nerve cell death in stroke and a safe and multifunctional drug that can block both routes in the brain will likely provide a better therapeutic outcome in patients with stroke. Derivatives of the lead structures of sulfasalazine and aspirin have led to the discovery of a new molecule, Neu2000, that has demonstrated excellent neuroprotection against NMDA- and free radical-induced cell death. Neu2000 is an NR2B-selective, moderate NMDA receptor antagonist with potent cell-permeable, spin trapping antioxidant action even at nanomolar concentrations. Nonclinical and human phase I studies demonstrated that Neu2000 can be translated to treat patients with stroke with better efficacy and therapeutic time window.

The goal of the present study was to examine the neuroprotective and functional significance of targeting both N-methyl-D-aspartate (NMDA) receptor-mediated excitotoxicity and oxidative stress using a dual-acting compound, Neu2000, in rat model of moderate spinal cord injury (SCI). An initial set of experiments was conducted in uninjured rats to study the pharmacokinetic profile of Neu2000 following intraperitoneal and intravenous administration. A second experiment measured free radical production in mitochondria isolated from sham or injured spinal cords of animals receiving vehicle or Neu2000 treatment. A third set of animals was divided into three treatment groups consisting of vehicle treatment, a single dose of Neu2000 (50 mg/kg) administered at 10 min following injury, or a repeated treatment paradigm consisting of a single bolus of Neu2000 at 10 min following injury (50 mg/kg) plus a maintenance dose (25 mg/kg) administered every 24 h for an additional 6 days. Animals were tested once a week for a period of 6 weeks for evidence of locomotor recovery in an open field and kinematic analysis of fine motor control using the DigiGait Image Analysis System. At the end of the testing period, spinal cord reconstruction was performed to obtain nonbiased stereological measures of tissue sparing. The results of this study demonstrate that Neu2000 treatment significantly reduced the production of mitochondrial free radicals and improved locomotor outcomes that were associated with a significant increase in the volume of spared spinal cord tissue.