title: Genotoxic effect and rat hepatocyte death occurred after oxidative stress induction and antioxidant gene downregulation caused by long term fluoride exposure.
abstract: Studies focusing on possible genotoxic effects of excess fluoride are contradictory and inconclusive. Currently, studies have reported a probable link to oxidative stress, DNA damage and apoptosis induced by fluoride in rat hepatocytes. We developed an in vivo study administering three doses of fluoride by gavage given to rats for 60 day. Micronucleus test was applied to investigate genotoxic potential of fluoride. The TUNEL method determined DNA fragmentation and apoptosis. Biochemical parameters to investigate mitochondrial swelling and oxidative stress. Semi-quantitative RT-PCR and immunostaining to determine mRNA and protein expression of antioxidant enzymes. Analyses of the hepatic function and morphology were performed. Our results revealed the genotoxic potential of fluoride but did not confirm mitochondrial swelling nor an increase of positive TUNEL labelling induced by fluoride, indicating absence of apoptosis. Oxidative stress induction was confirmed and is probably associated to DNA damage. Cell death events such as empty nuclear spaces, cytoplasm degeneration, nuclear pyknosis, karyorrhexis and karyorrhexis followed by karyolysis were observed. Hepatic function did not appear to be significantly modified makes no evidence of necrosis and suggesting other cell death pathway, the autophagic. In conclusion, prolonged fluoride intake at chosen concentrations caused imbalance of the cellular oxidative state, affected DNA and disrupted cellular homeostasis. It is recommended that fluoride supplementation requires a fresh consideration in light of the current study.
authors.affiliation: São Paulo State University (UNESP), Department of Biology, Institute of Biosciences, Avenida 24-A, nº 1515, Bela Vista, CEP 13506-900, Rio Claro, São Paulo, Brazil.
authors.forename: F D
authors.initials: FD
authors.lastname: Campos-Pereira
authors.affiliation: Heath Sciences Nucleus, Hermínio Ometto University Center, UNIARARAS, Avenida Dr. Maximiliano Barutto, nº 500, Jd. Universitário, Araras, São Paulo, CEP 13607-339, Brazil.
authors.forename: L
authors.initials: L
authors.lastname: Lopes-Aguiar
authors.affiliation: Heath Sciences Nucleus, Hermínio Ometto University Center, UNIARARAS, Avenida Dr. Maximiliano Barutto, nº 500, Jd. Universitário, Araras, São Paulo, CEP 13607-339, Brazil.
authors.forename: F L
authors.initials: FL
authors.lastname: Renosto
authors.affiliation: Heath Sciences Nucleus, Hermínio Ometto University Center, UNIARARAS, Avenida Dr. Maximiliano Barutto, nº 500, Jd. Universitário, Araras, São Paulo, CEP 13607-339, Brazil.
authors.forename: G A S
authors.initials: GA
authors.lastname: Nogueira
authors.affiliation: Heath Sciences Nucleus, Hermínio Ometto University Center, UNIARARAS, Avenida Dr. Maximiliano Barutto, nº 500, Jd. Universitário, Araras, São Paulo, CEP 13607-339, Brazil.
authors.forename: E F D
authors.initials: EF
authors.lastname: Costa
authors.affiliation: Heath Sciences Nucleus, Hermínio Ometto University Center, UNIARARAS, Avenida Dr. Maximiliano Barutto, nº 500, Jd. Universitário, Araras, São Paulo, CEP 13607-339, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Barbieri Pulz
authors.affiliation: Structural and Functional Biology Laboratory (LABEF), Federal University of São Carlos - UFSCAR, Rodovia João Leme dos Santos, Km 110 - SP-264, CEP 18052-780, Sorocaba, São Paulo, Brazil.
authors.forename: E C M
authors.initials: EC
authors.lastname: Silva-Zacarin
authors.affiliation: Graduate Program in Biomedical Sciences, Hermínio Ometto University Center, UNIARARAS, Avenida Dr. Maximiliano Barutto, nº 500, Jd. Universitário, CEP 13607-339, Araras, São Paulo, Brazil.
authors.forename: C A
authors.initials: CA
authors.lastname: Oliveira
authors.affiliation: Heath Sciences Nucleus, Hermínio Ometto University Center, UNIARARAS, Avenida Dr. Maximiliano Barutto, nº 500, Jd. Universitário, Araras, São Paulo, CEP 13607-339, Brazil.
authors.forename: A A
authors.initials: AA
authors.lastname: Pigoso
authors.affiliation: Reproductive Biology Laboratory, Structural and Functional Biology Department, State University of Campinas - UNICAMP, CP. 6109, Campinas, São Paulo, CEP 13083-863, Brazil. Electronic address: grazielaguiar@terra.com.br.
authors.forename: G D C
authors.initials: GD
authors.lastname: Severi-Aguiar
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects*; D015536:Down-Regulation / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005982:Glutathione Transferase / Q000235:genetics; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D008297:Male; D015162:Micronucleus Tests; D009153:Mutagens / Q000008:administration & dosage / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012969:Sodium Fluoride / Q000008:administration & dosage / Q000633:toxicity*; D013482:Superoxide Dismutase / Q000235:genetics
chemical_list: D005982:Glutathione Transferase; D009153:Mutagens; D012969:Sodium Fluoride; D013482:Superoxide Dismutase
keywords: Cell death; Hepatic injury; Micronuclei; Mitochondrial swelling; Oxidative stress