title: Increased DNA double-strand break was associated with downregulation of repair and upregulation of apoptotic factors in rat hippocampus after alcohol exposure.
abstract: Binge drinking is known to cause damage in critical areas of the brain, including the hippocampus, which is important for relational memory and is reported to be sensitive to alcohol toxicity. However, the roles of DNA double-strand break (DSB) and its repair pathways, homologous recombination (HR), and non-homologous end joining (NHEJ) in alcohol-induced hippocampal injury remain to be elucidated. The purpose of this first study was to assess alcohol-induced DNA DSB and the mechanism by which alcohol affects DSB repair pathways in rat hippocampus. Male Sprague-Dawley rats (8-10 weeks old) were put on a 4-day binge ethanol treatment regimen. Control animals were maintained under similar conditions but were given the vehicle without ethanol. All animals were humanely euthanized 24 h after the last dose of ethanol administration and the hippocampi were dissected for immunoblot and immunohistochemistry analysis. Ethanol exposure caused increased 4-hydroxynonenal (4-HNE) staining as well as elevated γH2AX and 53BP1 foci in hippocampal cells. Immunoblot analysis showed decreased Mre11, Rad51, Rad50, and Ku86 as well as increased Bax and p21 in samples from ethanol-treated rats. Additionally, we also observed increased activated caspase3 staining in hippocampal cells 24 h after ethanol withdrawal. Taken together, our data demonstrated that ethanol concurrently induced DNA DSB, downregulated DSB repair pathway proteins, and increased apoptotic factors in hippocampal cells. We believe these findings will provide the impetus for further research on DNA DSB and its repair pathways in relation to alcohol toxicity in brain.
authors: Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA.
authors: Shubhankar
authors: S
authors: Suman
authors: Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA.
authors: Santosh
authors: S
authors: Kumar
authors: Department of Pediatrics, Georgetown University Medical Center, Washington, DC 20057, USA.
authors: Prosper
authors: P
authors: N'Gouemo
authors: Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA. Electronic address: kd257@georgetown.edu.
authors: Kamal
authors: K
authors: Datta
mesh_terms: D000447:Aldehydes / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D004260:DNA Repair / Q000187:drug effects*; D015536:Down-Regulation / Q000187:drug effects*; D000431:Ethanol / Q000633:toxicity*; D006624:Hippocampus / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D000072200:Ku Autoantigen / Q000378:metabolism; D000076228:MRE11 Homologue Protein / Q000378:metabolism; D008297:Male; D010750:Phosphoproteins / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D000071857:Tumor Suppressor p53-Binding Protein 1 / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000447:Aldehydes; D006657:Histones; C512690:Mre11 protein, rat; D010750:Phosphoproteins; D000071857:Tumor Suppressor p53-Binding Protein 1; D051028:bcl-2-Associated X Protein; C577575:gamma-H2AX protein, rat; D000431:Ethanol; D051135:Rad51 Recombinase; D000076228:MRE11 Homologue Protein; D053148:Caspase 3; D020741:rho GTP-Binding Proteins; D000072200:Ku Autoantigen; C027576:4-hydroxy-2-nonenal
keywords: Alcohol; DNA damage; DNA double-strand break; DNA repair; Hippocampus; Non-homologous end joining