Adaptation of Rats to Selenium Intake

Abstract

Changes of liver selenium after intake of organic selenium at different levels and for various lengths of time were studied in 236 young rats. In litters born to mothers fed a diet containing 4.5 ppm selenium (in seleniferous sesame press cake) and kept on this diet after weaning, the liver levels decreased steadily; these levels increased in stock rats fed the same diet. The graphical presentation of these changes resulted in two straight lines, crossing each other. When the selenium diet was fed to dams 5 to 7 days prior to parturition and thereafter, the liver levels of the litters rose rapidly; liver levels increased at a slower rate in rats born to females fed the diet 15 to 19 days prior to birth and decreased in litters from mothers kept on the diet prior to mating. When litters from stock females were nursed by dams fed the seleniferous diet during pregnancy and changed to the stock ration after the birth of their litters, the liver selenium levels rose rapidly for about 3 weeks after weaning and then decreased. On a diet containing 10 ppm selenium, liver values in rats from the stock colony rose for 2 to 3 weeks to high levels and then decreased. Animals bred on the diet containing 4.5 ppm selenium exhibited a slower, more continuous rise of liver selenium when the high selenium diet was fed. The results suggest the existence of an adaptation mechanism which allows rats exposed to chronic selenium ingestion to store less of this element than previously unexposed controls.