Endothelin-A receptor antagonist BQ123 potentiates acetaminophen induced hypothermia and reduces infarction following focal cerebral ischemia in rats

Endothelin antagonists are being investigated to prevent neuronal loss after cerebral ischemia. Acetaminophen has been tried in stroke patients to produce hypothermia so that injury following cerebral ischemia can be reduced. The aim of this study was to assess the effect of BQ123, an endothelin-A receptor antagonist, alone and in combination with acetaminophen on neurological outcome, oxidative stress and infarct volume in rats subjected to focal ischemia by occlusion of the middle cerebral artery. In normal rats, acetaminophen decreased, while BQ123 did not produce any change in body temperature, but rats treated with BQ123 and acetaminophen produced a significantly greater (41%) hypothermic response compared to acetaminophen group. In rats subjected to middle cerebral artery occlusion, neurologic deficit was observed; acetaminophen alone did not improve, but BQ123 alone and in combination with acetaminophen produced a significant improvement in neurological deficit. The level of malondialdehyde (MDA) increased and reduced glutathione (GSH) decreased in the brain following ischemia; acetaminophen did not but BQ123 alone and in combination with acetaminophen decreased MDA and increased GSH levels in ischemic rats. Cerebral ischemia produced significant infarction, the infarct volume decreased in response to BQ123 and its combination with acetaminophen. The infarct volume, MDA level and neurological deficit in ischemic rats significantly improved in rats treated with both BQ123 and acetaminophen compared to BQ123 alone. The results demonstrate that a combination of acetaminophen and BQ123 is more effective in reducing the neuronal damage following cerebral ischemia, and this combination may be worth investigating in stroke patients. (C) 2010 Elsevier BM. All rights reserved.