Effect of Chronic Lead Intoxication on Risky Behavior in Mice

With industrialization of human societies, pollutants like lead have entered in the life cycle, causing harmful effects on body organs. No sufficient studies have been done on the effects of pollutants on behavior. The aim of this study was to investigate possible effects of lead on some measurable behaviors of an animal model. Forty eight male adult mice were divided into 4 groups of 12 each. Lead acetate was added at concentrations of 0, 5, 50, or 500 ppm to the drinking water of the animals for 4 weeks (28 days). On day 29, animals were placed on an Elevated Plus maze (EPM) for 5 min and the time in sec spent was measured on closed arms, open arms and the end 1/3rd of the open arms. Increased time on open arms, particularly the end 1/3rd was considered to reflect an enhanced risk-accepting behavior. In this study, it was shown that lead exposure caused an increased number of entrance (P=0.006) and time spent (P=0.034) by mice on open arms of the EPM. There was a positive correlation between the concentration of lead acetate and those two effects. The present study demonstrated that lead poisoning may decrease normal anxiety in mice and increase risky behavior in this species. Clinical studies on human subjects with risky behavior are strongly suggested in order to find a possible relation between chronic exposures to lead as well as plasma concentration of lead with the extent of this kind of behavior.