Abstract
Selenium is an essential element with a narrow margin between beneficial and toxic effects. This study was aimed to determine the neurobehavioral changes resulted from the prenatal exposure of mice to high doses of sodium selenite during fetal and early postnatal development. Atomic absorption for monitoring the placental transfer of selenium to offspring was employed. The developmental observations as well as the behavioral tests, such as sensory motor reflexes, and learning and memory test in automatic reflex conditioner (shuttle box) (active avoidance responses) were applied. Adult mice was assigned into three groups: the first group was remained as a control group given phosphate buffered saline; the second and the third groups were orally administrated sodium selenite at doses of 1 mg/kg and 4 mg/kg of the diet, respectively started from the 7(th) day to the end of the gestation period. Appearance of body hair and opening of eyes of the pups from treated mothers were delayed in a dose-dependent manner. The body weight gain came significantly lower than those of the control especially at the higher dose. Selenite also inhibited the sensory motor reflexes in all elements of acts and postures in a dose dependent manner. The active avoidance training-test indicated that selenite exposure was associated with learning impairment. Acetylcholine recorded a significant decrease in almost all the period of this study. By using atomic absorption, we found a significant high concentration of selenium in the brain, liver and kidney until the 40(th) postnatal day, indicating active transfer of selenium from mothers to embryos.