Neuroprotective mechanisms of puerarin in middle cerebral artery occlusion-induced brain infarction in rats

摘要

Puerarin, a major isoflavonoid derived from the Chinese medical herb Radix puerariae (kudzu root),has been reported to be useful in the treatment of various cardiovascular diseases. In the presentstudy, we examined the detailed mechanisms underlying the inhibitory effects of puerarin oninflammatory and apoptotic responses induced by middle cerebral artery occlusion (MCAO) inrats. Treatment of puerarin (25 and 50 mg/kg; intraperitoneally) 10 min before MCAO dosedependentlyattenuated focal cerebral ischemia in rats. Administration of puerarin at 50 mg/kg,showed marked reduction in infarct size compared with that of control rats. MCAO-induced focalcerebral ischemia was associated with increases in hypoxia-inducible factor-1alpha (HIF-1alpha), induciblenitric oxide synthase (iNOS), and active caspase-3 protein expressions as well as the mRNAexpression of tumor necrosis factor-alpha (TNF-alpha) in ischemic regions. These expressions weremarkedly inhibited by the treatment of puerarin (50 mg/kg). In addition, puerarin (10~50 muM)concentration-dependently inhibited respiratory bursts in human neutrophils stimulated by formyl-Met-Leu-Phe. On the other hand, puerarin (20~500 muM) did not significantly inhibit thethiobarbituric acid-reactive substance reaction in rat brain homogenates. An electron spinresonance (ESR) method was conducted on the scavenging activity of puerarin on the free radicalsformed. Puerarin (200 and 500 muM) did not reduce the ESR signal intensity of hydroxyl radicalformation. In conclusion, we demonstrate that puerarin is a potent neuroprotective agent onMCAO-induced focal cerebral ischemia in vivo. This effect may be mediated, at least in part, by theinhibition of both HIF-1alpha and TNF-alpha activation, followed by the inhibition of inflammatoryresponses (i.e., iNOS expression), apoptosis formation (active caspase-3), and neutrophilactivation, resulting in a reduction in the infarct volume in ischemia-reperfusion brain injury. Thus,puerarin treatment