Cell death is associated with reduced base excision repair during chronic alcohol administration in adult rat brain.
The cell death cascades in different brain regions namely hippocampus and frontal cortex of rats fed with 10% (v/v) ethanol for 12 weeks, was examined. After Western blotting, different cell death associated proteins displayed differential activation in the two regions observed. In hippocampus, activated caspase-3 and caspase-7 resulted in subsequent cleavage of poly(ADP-ribose) polymerase-1 (PARP-1). Cytochrome c release to cytosol and apoptosis inducing factor (AIF) translocation to nucleus was marginal. B-cell leukemia/lymphoma-2 (Bcl-2) translocation to cytosol was significant whereas Bcl-2-associated X protein (Bax) and Bcl-associated death protein (Bad) were largely located in cytosol. Further, upregulation of N-methyl D-aspartate receptor subunit 1 (NMDAR1), N-methyl D-aspartate receptor subunit 2B (NMDAR2B), N-methyl D-aspartate receptor subunit 2C (NMDAR2C) and activation of calpains were observed. In frontal cortex, caspase-3 activation, cleavage of PARP-1 and nuclear translocation of AIF were more pronounced. Moreover, cytochrome c release to cytosol, Bcl-2 translocation to cytosol was evident. However, levels of Bax, Bad, NMDA receptor subunits, and calpains were unaffected. Apoptosis was further substantiated by in situ staining for terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL). Results of the current study revealed that frontal cortex exhibits a higher level of ethanol-induced apoptosis relative to hippocampus. DNA polymerase beta assay and immunoblot showed significant loss in base excision repair in ethanol treated group.
Bhupanapadu Sunkesula
Solomon Raju
SR
Centre for Biotechnology and Department of Animal Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India.
Swain
Umakanta
U
Babu
Phanithi Prakash
PP
D000437:Alcoholism; D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism* / Q000473:pathology*; D002154:Calpain / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000502:physiology*; D004260:DNA Repair; D004789:Enzyme Activation; D000431:Ethanol / Q000008:administration & dosage* / Q000378:metabolism; D006801:Humans; D020287:In Situ Nick-End Labeling; D008297:Male; D021122:Protein Subunits / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013347:Subcellular Fractions / Q000737:chemistry
D021122:Protein Subunits; D016194:Receptors, N-Methyl-D-Aspartate; D000431:Ethanol; D002154:Calpain; D020169:Caspases