Selenoprotein W, Selenium and Glutathione Peroxidase in Rat and Sheep Brains and in Brain Cell Cultures

The effects of various selenium (Se) levels on seleno-protein W (SeW) content, Se concentration and glutathione peroxidase (GPX) activity in various parts of the brain from sheep and rats, and in glial and neuronal cells from rats were determined. Se concentration and GPX activity were significantly lower in whole brains from Se deficient lambs than from those receiving Se, but the SeW levels were not different. This is in contrast to the heart and muscle where SeW levels were significantly lower in deficient lambs. As the Se status of lambs increased, GPX and SeW increased in the brain cortex, cerebellum and thalamus. Different patterns from the lambs were noted for the increase of GPX and SeW levels in the cortex and cerebellum from rats fedvarious levels of Se. SeW increased at a faster rate in glial cells than either in L8 muscle or neuronal cells but a different pattern was found for GPX activity. Although GPX activity increased with Se content, the differences between cells were not as great as with SeW. The rate of decline was different for SeW levels and GPX activity upon removal of Se from the media with the three types of cells. SeW and GPX activity decreased at about the same rate in L8 muscle cells, GPX activity decreased faster than SeW in neuronal cells, but SeW decreased faster than GPX activity in glial cells when Se was removed from the medium. Thus, Se appears to be metabolized differently by various parts of the brain and by different brain cells.