Intra-carotid cold magnesium sulfate infusion induces selective cerebral hypothermia and neuroprotection in rats with transient middle cerebral artery occlusion

Local hypothermia induced by intra-arterial infusion of cold saline reduces brain injury in ischemic stroke. Administration of magnesium sulfate through the internal carotid artery is also known to reduce ischemic brain damage. The neuroprotective effects of combination therapy with local endovascular hypothermia and intra-carotid magnesium sulfate infusion has not been evaluated. The aim of the study was to determine whether infusion of intra-carotid cold magnesium offers neuroprotective efficacy superior to cold saline infusion alone. Sixty-eight Sprague-Dawley rats were subjected to 3 h of middle cerebral artery occlusion and were randomly divided into six groups: sham-operated group; stroke control group; local cold magnesium infusion group; local cold saline infusion group; local normothermic magnesium infusion group; and local normothermic saline infusion group. Before reperfusion, ischemic rats received local infusion or no treatment. Infarct volume, neurological deficit, and brain water content were evaluated at 48 h after reperfusion. Selective brain hypothermia (33-34 A degrees C) was successfully induced by intra-carotid cold infusion. Local cold saline infusion and local cold magnesium infusion reduced the infarct volumes by 48 % (p < 0.001) and 65 % (p < 0.001), respectively, compared with stroke controls. Brain water content was decreased significantly in animals treated with local cold magnesium infusion. Furthermore, the rats given a local cold magnesium infusion had the best neurological outcome. Local normothermic infusion failed to improve ischemic brain damage. These data suggest that local hypothermia induced by intra-carotid administration of cold magnesium is more effective in reducing acute ischemic damage than infusion of cold saline alone.