3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors protect cortical neurons from excitotoxicity

3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors, or statins, reduce the incidence of strokes and reduce infarct volume after cerebral ischemia in mice. Excitoxicity caused by overstimulation of glutamate receptors is a major cause of neuronal death after an ischemic brain insult. Experiments presented here explored whether statins protect cultured neurons from excitotoxic death caused by the glutamate receptor agonist NMDA. Treatment with statins preserved NMDA receptor-expressing cortical neurons and potently and substantially reduced lactate dehydrogenase release caused by exposure of embryonic mouse neocortical cultures to NMDA. The rank order of neuroprotective potency was rosuvastatin = simvastatin > atorvastatin = mevastatin > pravastatin, which is similar to the known rank order of potency for inhibition of the HMG-CoA reductase enzyme. Resistance of cultures to NMDA excitotoxicity developed after several days of statin exposure. Neuroprotection by rosuvastatin was coincident with a decrease in cell sterols and occurred with a similar potency as inhibition of cholesterol biosynthesis. Neuroprotection was substantially attenuated by cotreatment with either mevalonate or cholesterol and was mimicked by acute treatment with the cholesterol-extracting agent beta-cyclodextrin, suggesting that neuroprotection was mediated by depletion of a cellular pool of cholesterol because of the inhibition of cholesterol biosynthesis. These results suggest the possibility that, in addition to effects on cerebrovascular function, statins have the potential to render cortical neurons more resistant to NMDA-induced excitotoxic death as a result of changes in cell cholesterol homeostasis.