Effects of lead (Pb) exposure on anxiety in rats

Anxiety is one of the most common but treatable mental disorders. Lead (Pb) seems to be involved in the etiology of some psychological disorders including anxiety. This study investigated the effects of chronic Pb exposure on anxiety during different stages of rat's development. In order to conduct this study, Wistar rats were exposed to 500 ppm of lead (Pb) in their drinking water in the three stages: embryonic, pre-weaning, and post-weaning stages. The first group received Pb since the the beginning of their embryonic stage until the end of this period through addition to the drinking-water of their mothers. The second group received it from their birth until weaning, and the third group from weaning until 42nd day after birth. By using elevated plus-maze anxiety level in the male rats, each weighing 250-300 g, was studied. For data analysis, variance analysis followed by Tukey test was used. Exposure to Pb can decrease the entrance into and staying at open arms exploration (from 41% to 23%), and staying time (from 119 to 60 S). These changes in the embryonic group was greater than the other groups (P<0.01) It was found that Pb exposure during developmental stage has an anxiogenic effect on rats during their first developmental stage. The present study supports the hypothesis that animals are sensitive to neurotoxic effects of Pb exposure in the early stages of developmental period of the central nervous system.