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Activation of Poly(ADP‐Ribose) Polymerase in the Rat Hippocampus May Contribute to Cellular Recovery Following Sublethal Transient Global Ischemia
Author(s) -
Nagayama Tetsuya,
Simon Roger P.,
Chen Dexi,
Henshall David C.,
Pei Wei,
Stetler R. Anne,
Chen Jun
Publication year - 2000
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2000.0741636.x
Subject(s) - poly adp ribose polymerase , nad+ kinase , microbiology and biotechnology , western blot , ischemia , polymerase , parp inhibitor , immunostaining , biology , blot , hippocampus , hippocampal formation , dna repair , messenger rna , endocrinology , medicine , enzyme , biochemistry , dna , immunology , immunohistochemistry , gene
We have investigated the role of poly(ADP‐ribose)polymerase (PARP) activation in rat brain in a model of sublethal transientglobal ischemia. Adult male rats were subjected to 15 min of ischemia withbrain temperature reduced to 34°C, followed by 1, 2, 4, 8, 16, 24, and 72h of reperfusion. PARP mRNA expression was examined in the hippocampus usingquantitative RT‐PCR, northern blot analysis, and in situ hybridization.Protein expression was assessed using western blot analysis. PARP enzymaticactivity was investigated by measuring nuclear [ 3 H]NADincorporation. The presence of poly(ADP‐ribose) polymers was assessedimmunocytochemically. Although PARP mRNA and protein expressions were notaltered after ischemia, enzymatic activity was increased 4.37‐fold at 1 h( p < 0.05 vs. sham) and 1.73‐fold ( p < 0.05 vs. sham)at 24 h of reperfusion. Immunostaining demonstrated the presence ofpoly‐(ADP‐ribose) polymers in CA1 neurons. Cellular NAD + levelswere not significantly altered at any time point. Furthermore, systemicadministration of 3‐aminobenzamide (30 mg/kg), a PARP inhibitor, prevented theincrease in PARP activity at 1 and 24 h of reperfusion, significantlydecreased the number of surviving neurons in the hippocampal CA1 region 72 hafter ischemia ( p < 0.01 vs. sham), and increased DNAsingle‐strand breaks assessed as DNA polymerase I‐mediated biotin‐dATPnick‐translation (PANT)‐positive cells ( p < 0.01 vs. sham).Furthermore, using an in vitro DNA repair assay, 3‐aminobenzamide (30 mg/kg)was shown to block DNA base excision repair activity. These data suggest thatthe activation of PARP, without subsequent NAD + depletion, following mild transient ischemia may be neuroprotective in the brain.