Protective Effects of Scutellarin Against Cerebral Ischemia in Rats: Evidence for Inhibition of the Apoptosis-Inducing Factor Pathway

Abstract

Scutellarin (Scu) is the major active principle (flavonoid) extracted from Erigeron breviscapus (Vant.) Hand-Mazz, a Chinese herbal medicine. In this paper, we investigated the effects of Scu on brain injury through the inhibition of AIF-mediated apoptosis induced by transient focal brain ischemia in rats. Rats were treated with Scu for 7 d and then subjected to cerebral ischemia/reperfusion (I/R) injury induced by a middle cerebral artery occlusion (MCAO). After 2 h of ischemia and 22 h of reperfusion, the infarct volume and the neurological deficit were determined by TTC staining and Longa’s score. In situ end-labeling of nuclear DNA fragments (TUNEL) was employed to determine the degree of DNA fragmentation. NAD content and PARP activity in brain homogenate were determined. The expression of AIF in the nucleus was analyzed by Western blot. The present study showed that Scu significantly reduced the infarct volume and ameliorated the neurological deficit. An increase in the number of TUNEL-positive cells and a decrease in the NAD level were also observed after 2 h of ischemia and 22 h of reperfusion. At the same time, Scu (50 and 75 mg kg⁻¹, i. g.) treatment reversed brain NAD depletion and reduced DNA fragmentation. Scu also inhibited PARP overactivation and AIF translocation from the mitochondria to the nucleus following cerebral I/R. These findings suggested that the neuroprotective effects of Scu on brain ischemic injury-induced apoptosis might be associated with inhibition of PARP-dependent mitochondrial dysfunction and subsequent translocation of AIF.

apoptosis - apoptosis-inducing factor - scutellarin - Erigeron breviscapus (Vant.) Hand-Mazz (Compositae) - cerebral ischemia - poly (ADP-ribose) polymerase

References

• 1 Liu P K. Ischemia-reperfusion-related repair deficit after oxidative stress: implications of faulty transcripts in neuronal sensitivity after brain injury.  J Biomed Sci. 2003;  10 4-13
• 2 Hurn P D, Vannucci S J, Hagberg H. Adult or perinatal brain injury: does sex matter?.  Stroke. 2005;  36 193-5
• 3 Lennmyr F, Karlsson S, Gerwins P, Ata K A, Terent A. Activation of mitogen-activated protein kinases in experimental cerebral ischemia.  Acta Neurol Scand. 2002;  106 333-40
• 4 Kao H, Takasawa R, Fukuda K, Shiokawa D, Sadanaga-Akiyoshi F, Ibayashi S. et al . DNA fragmentation in ischemic core and penumbra in focal cerebral ischemia in rats.  Mol Brain Res. 2001;  91 112-8
• 5 Chan P H. Reactive oxygen radicals in signaling and damage in the ischemic brain.  J Cereb Blood Flow Metab. 2001;  21 2-14
• 6 Yu S W, Wang H, Poitras M F, Coombs C, Bowers W J, Federoff H J. et al . Mediation of poly(ADP-ribose) polymerase-1-dependent cell death by apoptosis-inducing factor.  Science. 2002;  297 259-63
• 7 Cipriani G, Rapizzi E, Vannacci A, Rizzuto R, Moroni F, Chiarugi A. Nuclear poly (ADP-ribose) polymerase-1 rapidly triggers mitochondrial dysfunction.  J Biol Chem. 2005;  280 17 227-34
• 8 Ju B G, Solum D, Song E J, Lee K J, Rose D W, Glass C K. et al . Activating the PARP-1 sensor component of the groucho/TLE1 corepressor complex mediates a CaMKinase IIdelta-dependent neurogenic gene activation pathway.  Cell. 2004;  119 815-29
• 9 Daugas E, Susin S A, Zamzami N, Ferri K F, Irinopoulou T, Larochette N. et al . Mitochondrio-nuclear translocation of AIF in apoptosis and necrosis.  FASEB J. 2000;  14 729-39
• 10 Cheung E C, Melanson-Drapeau L, Cregan S P, Vanderluit J L, Ferguson K L, McIntosh W C. et al . Apoptosis-inducing factor is a key factor in neuronal cell death propagated by BAX-dependent and BAX-independent mechanisms.  J Neurosci. 2005;  25 1324-34
• 11 Plesnila N, Zhu C, Culmsee C, Groger M, Moskowitz M A, Blomgren K. Nuclear translocation of apoptosis-inducing factor after focal cerebral ischemia.  J Cereb Blood Flow Metab. 2004;  24 458-66
• 12 Culmsee C, Zhu C, Landshamer S, Becattini B, Wagner E, Pellechia M. et al . Apoptosis-inducing factor triggered by poly (ADP-ribose) polymerase and Bid mediates neuronal cell death after oxygen-glucose deprivation and focal cerebral ischemia.  J Neurosci. 2005;  25 10 262-72
• 13 Liu H, Yang X L, Wang Y, Tang X Q, Jiang D Y, Xu H B. Protective effects of scutellarin on superoxide-induced oxidative stress in rat cortical synaptosomes.  Acta Pharmacol Sin. 2003;  24 1113-7
• 14 Yang X F, He W, Lu W H, Zeng F D. Effects of scutellarin on liver function after brain I/R in rats.  Acta Pharmacol Sin. 2003;  24 1118-24
• 15 Hu X M, Zhou M M, Zeng F D. Neuroprotective effects of scutellarin on rat neuronal damage induced by cerebral ischemia/reperfusion.  Acta Pharmacol Sin. 2005;  26 1454-9
• 16 Zea Longa E, Weinstein P R, Carlson S, Cummins R. Reversible middle cerebral artery occlusion without craniotomy in rats.  Stroke. 1989;  20 84-91
• 17 Nisselbaum J S, Green S. A simple ultramicro method for determination of pyridine nucleotides in tissues.  Anal Biochem. 1969;  27 212-7
• 18 Cao G, Pei W, Ge H, Liang Q, Luo Y, Sharp F R. et al . In vivo delivery of a Bcl-xL fusion protein containing the TAT protein transduction domain protects against ischemic brain injury and neuronal apoptosis.  J Neurosci. 2002;  22 5423-31
• 19 Wang H, Yu S W, Koh D W, Lew J, Coombs C, Bowers W. et al . Apoptosis-inducing factor substitutes for caspase executioners in NMDA-triggered excitotoxic neuronal death.  J Neurosci. 2004;  24 10 963-73
• 20 Nakajima H, Kakui N, Ohkuma K, Ishikawa M, Hasegawa T. A newly synthesized poly (ADP-ribose) polymerase inhibitor, 2-methyl-3, 5, 7, 8-tetrahydrothiopyrano [4, 3-d] pyrimidine-4-one (DR2313): pharmacological profiles, neuroprotective effects and therapeutic time window in cerebral ischemia in rats.  J Pharmacol Exp Ther. 2004;  1 472-81
• 21 LaPlaca M C, Zhang J, Raghupathi R, Li J H, Smith F, Bareyre F M. et al . Pharmacologic inhibition of poly (ADP-ribose) polymerase is neuroprotective following traumatic brain injury in rats.  J Neurotrauma. 2001;  18 369-76
• 22 Hong S J, Dawson T M, Dawson V L. Nuclear and mitochondrial conversations in cell death: PARP-1 and AIF signaling.  Trends Pharmacol Sci. 2004;  25 259-64
• 23 Li X, Nemoto M, Xu Z, Yu S W, Shimoji M, Andrabi S A. et al . Influence of duration of focal cerebral ischemia and neuronal nitric oxide synthase on translocation of apoptosis-inducing factor to the nucleus.  Cell Neurosci. 2007;  144 56-65
• 24 Alberto C hiarugi. Poly (ADP-ribosyl)ation and stroke.  Pharmacol Res. 2005;  52 15-24
• 25 Ye H, Cande C, Stephanou N C, Jiang S, Gurbuxani S, Larochette N. et al . DNA binding is required for the apoptogenic action of apoptosis inducing factor.  NatuStruct Mol Biol. 2002;  9 680-4