Rats receiving fluoride during the whole pregnancy up to the 9th day of lactation showed, when isolated at 10th day of life, a reduced rate of ultrasonic vocalizations (UV) in male pups (NaF 5.0 mg) and, in 90th days male rats, an increase of the Pre-Pulse Inhibition (PPI) with a reduction of the Peak response to the Startle stimulus given alone. Newborn rat reactivity could represent a useful and validated model in anxiety studies which could be moored with the Acoustic Startle Reflex (ASR) and PPI, appropriate models to study, in adulthood, particular neurological and psychiatric disorders showing deficits in attention and sensory-motor gating (Tourettes' syndrome, obsessive compulsive disorders, Huntington's disease and schizophrenia).

Formaldehyde (FA), a volatile organic compound, is a ubiquitous air pollutant that is classified as 'Carcinogenic to humans (Group 1)' by IARC (2006). As a well-recognized human carcinogen, its carcinogenic mechanisms are still poorly understood. Previous studies have emphasized on genetic changes. However, little is known about the epigenetic mechanisms of FA exposure. In this study, We not only characterized the epigenomic response to long-term low-dose FA exposure in 16HBE cells, but also examined the expression of DNA methyltransferases (DNMTs) and the methyl-CpG-binding protein DNA-binding domain protein 2 (MBD2). Each week the 16HBE cells were treated with 10μM FA for 24 h (h). After 24 weeks (W) of exposure to FA, the level of genomic DNA methylation gradually decreased in a time-related manner. Moreover, our results showed that FA exposure down-regulated the expression of DNMT3a and DNMT3b at both mRNA and protein level, and up-regulated the levels of DNMT1 and MBD2 at both mRNA and protein level. Our study indicated that long-term FA exposure could disrupt genomic DNA methylation, which may be one of the possible underlying carcinogenic mechanisms of FA.

The biological responses of aluminum oxide (Al2 O3 ) nanoparticles (NPs) and nanowires (NWs) in cultured fibroblasts (L929) and macrophages (RAW264) were evaluated from their cytotoxicities and micromorphologic properties. Cultured cells were exposed to Al2 O3 NPs (13 nm diameter) and Al2 O3 NWs (2-6× 200-400 nm). Cytotoxicity and genotoxicity were examined by immunostaining with fluorescence microscopy, and nanomaterial localization was studied by using scanning electron microscopy and transmission electron microscopy. The NPs were cytotoxic and genotoxic, whereas the NWs were not. The scanning electron microscopy images showed that the NPs aggregate more on the cell surface than do the NWs. The transmission electron microscopy images showed that the NPs were internalized into the vesicle and nuclei, for both cell types. In contrast, numerous solid NWs were observed as large aggregatesin vesicles, but not in nuclei. Nuclear damage was confirmed by measuring cell viability and by immunostaining for NPs. The chemical changes induced by the NPs in the vesicles or cells may cause cell damage because of their large surface area per volume. The extent of NW entrapment was not sufficient to lower the viability of either cell type.

Nicotine has been reported to cause acute toxicity and to present long-term risks, such as chromosomal damage and genetic instability. The genotoxicity of nicotine may be mediated partly by an oxidative mechanism. We have evaluated the effects of the antioxidant vitamin C on nicotine-induced genotoxicity in mice. The comet assay and the micronucleus test were used to assess the effects of nicotine (15mg/kg) at different exposure times (2, 4, and 24h in the comet assay; 24h in the micronucleus test). Pretreatment with vitamin C 24h before nicotine exposure strongly protected mice against nicotine-induced DNA damage.