title: Diadenosine tetraphosphate protects against injuries induced by ischemia and 6-hydroxydopamine in rat brain.
abstract: Diadenosine tetraphosphate (AP4A), an endogenous diadenosine polyphosphate, reduces ischemic injury in the heart. In this study, we report the potent and protective effects of AP4A in rodent models of stroke and Parkinson's disease. AP4A, given intracerebroventricularly before middle cerebral artery (MCA) ligation, reduced cerebral infarction size and enhanced locomotor activity in adult rats. The intravenous administration of AP4A also induced protection when given early after MCA ligation. AP4A suppressed terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) induced by hypoxia/reperfusion in primary cortical cultures, and reduced both ischemia-induced translocation of mitochondrial cytochrome c and the increase in cytoplasmic caspase-3 activity in vivo. The purinergic P2/P4 antagonist di-inosine pentaphosphate or P1-receptor antagonist sulfonylphenyl theophylline, but not the P2-receptor antagonist suramin, antagonized the effect of AP4A, suggesting that the observed protection is mediated through an anti-apoptotic mechanism and the activation of P1- and P4-purinergic receptors. AP4A also afforded protection from toxicity induced by unilateral medial forebrain bundle injection of 6-hydroxydopamine (6-OHDA). One month after lesioning, vehicle-treated rats exhibited amphetamine-induced rotation. Minimal tyrosine hydroxylase immunoreactivity was detected in the lesioned nigra or striatum. No KCl-induced dopamine release was found in the lesioned striatum. All of these indices of dopaminergic degeneration were attenuated by pretreatment with AP4A. In addition, AP4A reduced TUNEL in the lesioned nigra 2 d after 6-OHDA administration. Collectively, our data suggest that AP4A is protective against neuronal injuries induced by ischemia or 6-OHDA through the inhibition of apoptosis. We propose that AP4A may be a potentially useful target molecule in the therapy of stroke and Parkinson's disease.
authors.affiliation: National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA. ywang@intra.nida.nih.gov
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Chen-Fu
authors.initials: CF
authors.lastname: Chang
authors.forename: Marisela
authors.initials: M
authors.lastname: Morales
authors.forename: Yung-Hsiao
authors.initials: YH
authors.lastname: Chiang
authors.forename: Brandon K
authors.initials: BK
authors.lastname: Harvey
authors.forename: Tsung-Ping
authors.initials: TP
authors.lastname: Su
authors.forename: Li-I
authors.initials: LI
authors.lastname: Tsao
authors.forename: Suyu
authors.initials: S
authors.lastname: Chen
authors.forename: Christoph
authors.initials: C
authors.lastname: Thiemermann
mesh_terms: D000818:Animals; D017209:Apoptosis; D001794:Blood Pressure; D002545:Brain Ischemia / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D015687:Cell Hypoxia; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000098:blood supply; D002544:Cerebral Infarction / Q000517:prevention & control; D015226:Dinucleoside Phosphates / Q000627:therapeutic use*; D004298:Dopamine / Q000378:metabolism; D018476:Hypokinesia / Q000517:prevention & control; D008124:Locomotion; D009474:Neurons / Q000166:cytology / Q000187:drug effects; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D016627:Oxidopamine; D010302:Parkinson Disease, Secondary / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control*; D051381:Rats; D011983:Receptors, Purinergic / Q000378:metabolism; D012039:Regional Blood Flow; D020521:Stroke / Q000503:physiopathology
chemical_list: D015226:Dinucleoside Phosphates; D018696:Neuroprotective Agents; D011983:Receptors, Purinergic; C020733:diadenosine tetraphosphate; D016627:Oxidopamine; D004298:Dopamine