Systemic genotoxic effects of tobacco-related nitrosamines following oral and inhalational administration to Sprague-Dawley rats

Abstract

An ex vivo model to detect nonspecific DNA damage in different rat tissues has been developed and employed to study systemic properties of tobacco-specific N-nitrosamines. One hour after treatment of rats with the carcinogens, primary, intact cells were isolated from various organs. Viability of the cells was monitored by trypan blue exclusion. Genotoxicity was determined by alkaline elution, in situ nick translation or microgel electrophoresis. We found that oral application of 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces genotoxic effects in the liver (3.125-50 mg/kg), whereas N-nitrosonornicotine (NNN) is only moderately active (50-100 mg/kg). Furthermore, oral administration of NNK, NNN, and of N-nitrosodimethylamine (NDMA), induces DNA damage in the nasal cavity. In peripheral blood lymphocytes genotoxicity of NDMA (less than 2 mg/kg), but not of NNK (50 mg/kg), was observed. NDMA and NNK are just as genotoxic in the liver when administered by inhalation as orally (effective doses: 0.1-1 and 50 mg/kg, respectively). For human cancer, these results indicate that in addition to the susceptibilities in local organs (oral cavity after snuff dipping and lung after tobacco smoke inhalation), these nitrosamines also pose a risk systemically for more remote organs.

Tobacco Constituents and Additives

“…These reactions may develop into malignant changes. In rats, too, exposure to the tobacco-specific nitrosamines NNK and NDMA has led to DNA damage to cells of the nasal mucosa and to lymphocyte changes, with the overall result that these animal studies indicate genotoxic effects of tobacco constituents not only in the nose, but also in the liver [102].…”

Assessment of the DNA Damage in Human Sperm and Lymphocytes Exposed to the Carcinogen Food Contaminant Furan with Comet Assay

“…The cells were checked for their viability before the start and after the completion of the experiment using trypan blue dye (Pool-Zobel et al 1992). Preparation of the slides for the comet assay and subsequent electrophoresis, and staining were carried as previously described (Anderson et al, 1994) for the lymphocytes and the sperm (WHO 2000; Anderson et al 1997a,b), using a modification of the methods of Singh et al 1988Singh et al , 1989.…”

Chemopreventive effect of bilberry (Vaccinium myrtillus) against cisplatin-induced oxidative stress and DNA damage as shown by the comet assay in peripheral blood of rats

“…Lymphocytes were isolated by Biocoll separating solution. Cell viability was determined by the trypan blue exclusion technique (Pool-Zobel et al 1992). Cell viability was 98%.…”