Methazolamide and melatonin inhibit mitochondrial cytochrome C release and are neuroprotective in experimental models of ischemic injury.

BACKGROUND AND PURPOSE The identification of a neuroprotective drug for stroke remains elusive. Given that mitochondria play a key role both in maintaining cellular energetic homeostasis and in triggering the activation of cell death pathways, we evaluated the efficacy of newly identified inhibitors of cytochrome c release in hypoxia/ischemia induced cell death. We demonstrate that methazolamide and melatonin are protective in cellular and in vivo models of neuronal hypoxia. METHODS The effects of methazolamide and melatonin were tested in oxygen/glucose deprivation-induced death of primary cerebrocortical neurons. Mitochondrial membrane potential, release of apoptogenic mitochondrial factors, pro-IL-1beta processing, and activation of caspase -1 and -3 were evaluated. Methazolamide and melatonin were also studied in a middle cerebral artery occlusion mouse model. Infarct volume, neurological function, and biochemical events were examined in the absence or presence of the 2 drugs. RESULTS Methazolamide and melatonin inhibit oxygen/glucose deprivation-induced cell death, loss of mitochondrial membrane potential, release of mitochondrial factors, pro-IL-1beta processing, and activation of caspase-1 and -3 in primary cerebrocortical neurons. Furthermore, they decrease infarct size and improve neurological scores after middle cerebral artery occlusion in mice. CONCLUSIONS We demonstrate that methazolamide and melatonin are neuroprotective against cerebral ischemia and provide evidence of the effectiveness of a mitochondrial-based drug screen in identifying neuroprotective drugs. Given the proven human safety of melatonin and methazolamide, and their ability to cross the blood-brain-barrier, these drugs are attractive as potential novel therapies for ischemic injury.