title: Poly(ADP-ribose) polymerase inhibition prevents both apoptotic-like delayed neuronal death and necrosis after H(2)O(2) injury.
abstract: Toxic reactive oxygen species (ROS) such as hydrogen peroxide, nitric oxide, superoxide, and the hydroxyl radical are generated in a variety of neuropathological conditions and cause significant DNA damage. We determined the effects of 3-aminobenzamide (AB), an inhibitor of the DNA repair enzyme poly(ADP-ribose) polymerase (PARP), on cell death in differentiated PC12 cells, a model of sympathetic neurons, after H(2) O(2) injury. Exposure to 0.5 mm H(2) O(2) resulted in a significant decrease in intracellular NAD(H), NADP(H), and ATP levels. This injury resulted in the death of 90% of the cells with significant necrosis early (2 h) after injury and increased apoptosis (12-24 h after injury), as measured by PS exposure and the presence of cytoplasmic oligonucleosomal fragments. Treatment with 2.5 mm AB restored pyridine nucleotide and ATP levels and ameliorated cell death (65% versus 90%) by decreasing the extent of both necrosis and apoptosis. Interestingly, we observed that H(2) O(2) -induced injury caused a delayed cell death exhibiting features of apoptosis but in which caspase-3 like activity was absent. Moreover, pretreatment with AB restored caspase-3-like activity. Our results suggest that apoptosis and necrosis are both triggered by PARP overactivation, and that maintenance of cellular energy levels after injury by inhibiting PARP shifts cell death from necrosis to apoptosis.
authors.affiliation: Department of Anatomy and Neurosciences, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0652, USA.
authors.forename: Kasie K
authors.initials: KK
authors.lastname: Cole
authors.forename: J Regino
authors.initials: JR
authors.lastname: Perez-Polo
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001549:Benzamides / Q000494:pharmacology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000633:toxicity*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D009336:Necrosis; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D018696:Neuroprotective Agents / Q000494:pharmacology; D016716:PC12 Cells; D011064:Poly Adenosine Diphosphate Ribose / Q000096:biosynthesis; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D051381:Rats
chemical_list: D001549:Benzamides; D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D009243:NAD; D011064:Poly Adenosine Diphosphate Ribose; D009249:NADP; C025160:3-aminobenzamide; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D011065:Poly(ADP-ribose) Polymerases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases