In Scu On Cerebral Ischemia And Reperfusion Injury In Rats And To Parp / Aif-mediated Apoptotic Pathway Inhibition

Increasing evidence has shown that brain injury can develop as a result of cerebral ischemia-reperfusion due to stroke and other cardiovascular diseases. Cerebral ischemia/reperfusion(I/R) triggers a complex series of biochemical and molecular mechanisms that impairs neurological functions through breakdown of cellular integrity mediated by excitotoxic glutamatergic signaling, ionic imbalance, free-radical reactions.Scutellarin (Scu) is the major active principle (flavonoid) extracted from Erigeron breviscapus. Hand.-Mazz, a Chinese herbal medicine, which is a Ca2+ channels blocking agent used in the clinical therapy of cerebrovascular disorders. Studies have shown the protective effects of Scu on brain injury induced by cerebral ischemia /reperfusion through interaction with a wide variety of targets because of its anti-oxidation, anti-inflammatory and attenuating neuronal damage. The aim of this study is to investigate the effects of Scu on brain injury through the inhibition of AIF-mediated apoptosis induced by transient focal brain ischemia in rats.Part I The protective effects of Scu on cerebral injury induced by brain ischemia-reperfusionRats were pretreated with Scu 25, 50, 75 mg·kg-1 for 7 d and then subjected to cerebral ischemia/reperfusion injury induced by a middle cerebral artery occlusion (MCAO). After 2 h ischemia and 22 h reperfusion, the neurological outcome was evaluated by the Longa's method; the infarct volume was assessed by TTC staining. Hematoxylin-Eosin (HE) staining was employed to determine the level of neuron damage. The results showed that Scu (50, 75mg·kg-1) significantly reduced the cerebral infarct volume and ameliorated the neurological deficit (P<0.05), and reduced the numbers of HE-positive staining cells after 22h reperfusion. These results showed that pretreatment with Scu could attenuate brain injury after cerebral ischemia/reperfusion.Part II The mechanism of Scu on apoptosis induced by transient focal cerebral ischemia in ratsRats were pretreated with Scu for 7 d and then subjected to brain ischemia/reperfusion injury induced by a middle cerebral artery occlusion (MCAO). After 2 h ischemia and 22 h reperfusion, in situ end-labeling of nuclear DNA fragmentation (TUNEL) were employed to determine the level of neuron apoptosis.NAD content and PARP activity in brain homogenate were determined. The expression of AIF in the mitochondria and in the nucleus were analyzed by western blot. The data showed that The increase numbers of HE-positive staining cells were significantly observed at 22 h after reperfusion, whiles the immunoreactivity was inhibited by Scu (50, 75 mg·kg-1) (P<0.05,vs vehicle-treated). At the meantime, Scu (50, 75 mg·kg-1)-treatment reverse brain NAD depletion, and inhibited PARP over activation and AIF translocation from the mitochondria to the nucleus following cerebral I/R.Conclusions:These findings suggested that the neuroprotective effects of Scu on brain ischemic injury-induced apoptosis were associated with inhibiting PARP-dependent mitochondrial dysfunction and subsequent translocation of AIF.