6-Hydroxydopamine and lipopolysaccharides induced DNA damage in astrocytes: involvement of nitric oxide and mitochondria.
The present study was conducted to investigate the effect of the neurotoxins 6-hydroxydopamine and lipopolysaccharide on astrocytes. Rat astrocyte C6 cells were treated with different concentration of 6-hydroxydopamine (6-OHDA)/lipopolysaccharides (LPS) for 24 h. Both neurotoxins significantly decreased the viability of astrocytes, augmented the expression of inducible nitric oxide synthase (iNOS) and the astrocyte marker--glial fibrillar acidic protein. A significantly decreased mitochondrial dehydrogenase activity, mitochondrial membrane potential, augmented reactive oxygen species (ROS) level, caspase-3 mRNA level, chromatin condensation and DNA damage was observed in 6-OHDA/LPS treated astroglial cells. 6-OHDA/LPS treatment also caused the significantly increased expression of iNOS and nitrite level. Findings showed that 6-OHDA/LPS treatment caused mitochondrial dysfunction mediated death of astrocytes, which significantly involve the nitric oxide. Since we have observed significantly increased level of iNOS along with mitochondrial impairment and apoptotic cell death in astrocytes, therefore to validate the role of iNOS, the cells were co-treated with iNOS inhibitor aminoguanidine (AG, 100 μM). Co-treatment of AG significantly attenuated the 6-OHDA/LPS induced cell death, mitochondrial activity, augmented ROS level, chromatin condensation and DNA damage. GFAP and caspase-3 expression were also inhibited with co-treatment of AG, although the extent of inhibition was different in both experimental sets. In conclusion, the findings showed that iNOS mediated increased level of nitric oxide acts as a key regulatory molecule in 6-OHDA/LPS induced mitochondrial dysfunction, DNA damage and apoptotic death of astrocytes.
Toxicology Division, CSIR-CDRI, Lucknow 226031, India.
Sonam
S
Gupta
Toxicology Division, CSIR-CDRI, Lucknow 226031, India.
Poonam
P
Goswami
Toxicology Division, CSIR-CDRI, Lucknow 226031, India.
Joyshree
J
Biswas
Center for Gene Regulation in Health and Disease, Department of Biological Sciences, Cleveland State University, Cleveland, OH, USA; Department of Genetics, Harvard Medical School, Boston, MA, USA.
Neeraj
N
Joshi
Toxicology Division, CSIR-CDRI, Lucknow 226031, India.
Sharad
S
Sharma
Toxicology Division, CSIR-CDRI, Lucknow 226031, India.
C
C
Nath
Toxicology Division, CSIR-CDRI, Lucknow 226031, India. Electronic address: sarika_singh@cdri.res.in.
Sarika
S
Singh
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002843:Chromatin / Q000737:chemistry / Q000187:drug effects; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D006146:Guanidines / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000633:toxicity*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009498:Neurotoxins / Q000037:antagonists & inhibitors / Q000633:toxicity*; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016627:Oxidopamine / Q000037:antagonists & inhibitors / Q000633:toxicity*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
D002843:Chromatin; D004791:Enzyme Inhibitors; D005904:Glial Fibrillary Acidic Protein; D006146:Guanidines; D008070:Lipopolysaccharides; D009498:Neurotoxins; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D016627:Oxidopamine; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D053148:Caspase 3; C004479:pimagedine
6-OHDA; Aminoguanidine; Caspase-3; DNA damage; LPS; iNOS