Showing papers by "Christer Hogstrand published in 2011"

Cerebral gene expression in response to single or combined gestational exposure to methylmercury and selenium through the maternal diet.

Abstract: Controversy remains regarding the safety of consuming certain types of seafood, particularly during pregnancy. While seafood is rich in vital nutrients, it may also be an important source of environmental contaminants such as methylmercury (MeHg). Selenium (Se) is one essential element present in seafood, hypothesised to ameliorate MeHg toxicity. The aim of the present study was to ascertain the impact of Se on MeHg-induced cerebral gene expression in a mammalian model. Microarray analysis was performed on brain tissue from 15-day-old mice that had been exposed to MeHg throughout development via the maternal diet. The results from the microarray analysis were validated using qPCR. The exposure groups included: MeHg alone (2.6 mg kg−1), Se alone (1.3 mg kg−1), and MeHg + Se. MeHg was presented in a cysteinate form, and Se as Se–methionine, one of the elemental species occurring naturally in seafood. Eight genes responded to Se exposure alone, five were specific to MeHg, and 63 were regulated under the concurrent exposure of MeHg and Se. Significantly enriched functional classes relating to the immune system and cell adhesion were identified, highlighting potential ameliorating mechanisms of Se on MeHg toxicity. Key developmental genes, such as Wnt3 and Sparcl1, were also identified as putative ameliorative targets. This study, utilising environmentally realistic forms of toxicants, delivered through the natural route of exposure, in association with the power of transcriptomics, highlights significant novel information regarding putative pathways of selenium and MeHg interaction in the mammalian brain.

Scientific Opinion on the safety and efficacy of selenium in the form of organic compounds produced by the selenium-enriched yeast Saccharomyces cerevisiae NCYC R645 (SelenoSource AF 2000) for all species

Abstract: SelenoSource AF 2000 is a selenium-containing inactivated yeast (Saccharomyces cerevisiae NCYC R645) enriched during the fermentation process with selenium, intended to be used as nutritional additive for all animal species and categories. Saccharomyces cerevisiae qualifies per se for Qualified Presumption of Safety (QPS); however, the FEEDAP Panel retains that, in this case, the mixture of selenocompounds in the additive is the subject of the evaluation, therefore the QPS approach does not apply. In the absence of data specific to the additive under consideration, and the very limited published data made available by the applicant on the tolerance of animal species to selenised yeast, the FEEDAP Panel is unable to conclude on the safety of SelenoSource AF 2000 in target animals. The FEEDAP Panel reiterates its former conclusion that the use of any selenised yeast would result in similar selenium deposition in animal tissues and products. To ensure consumer safety from consumption of tissues and products of animals treated with SelenoSource AF 2000, the FEEDAP Panel concludes that dietary selenium supplementation from this additive, as for other selenised yeasts, should not exceed a maximum of 0.2 mg Se/kg complete feed. In the absence of relevant information, the FEEDAP Panel could not assess the safety for the user. The use of SelenoSource AF 2000 in feed does not pose a additional risk to the environment, compared to other sources of selenium for which it will substitute. Based on the response of glutathione peroxidase activity and tissue/product deposition of selenium in poultry and pigs, the FEEDAP Panel considers SelenoSource AF 2000 an effective source of selenium for all species. © European Food Safety Authority, 2011

Cerebral gene expression and neurobehavioural development after perinatal exposure to an environmentally relevant polybrominated diphenylether (BDE47)

Abstract: Nutrients in seafood are known to be beneficial for brain development. Effects of maternal exposure to 2,2′,4,4′ tetrabromo diphenylether (BDE47) was investigated, alongside the potential ameliorating impact of seafood nutrients, through assessment of neurobehaviour and gene expression in brain and liver. Developing mice were exposed during gestation and lactation via dams dosed through casein- or salmon-based feed, spiked with BDE47. Two concentrations were used: a low level (6 μg/kg feed) representing an environmentally realistic concentration and a high level (1,900 μg/kg feed) representing a BDE47 intake much higher than expected from frequents consumption of contaminated seafood. Experimental groups were similar with respect to reproductive success, growth and physical development. Minor, transient changes in neurobehavioural metrics were observed in groups given the highest dose of BDE47. No significant differences in behaviour or development were seen on postnatal day 18 among maternally exposed offspring. Cerebral gene expression investigated by microarray analyses and validated by RT-qPCR showed low fold changes for all genes, despite dose-dependent accumulation of BDE47 in brain tissue. The gene for glutamate ammonia ligase was upregulated compared to control in the casein-based high BDE47diet, suggesting potential impacts on downstream synaptic transmission. The study supported a previously observed regulation of Igfbp2 in brain with BDE47 exposure. Genes for hepatic metabolic enzymes were not influenced by BDE47. Potential neurotoxic effects and neurobehavioural aberrations after perinatal exposure to high levels of BDE47 were not readily observed in mice pups with the present experimental exposure regimes and methods of analysis.