Behavioral changes in mice following lead administration during several stages of development

How lead ingestion during different developmental periods influences activity of mice was investigated. Binghamton Heterogenous Stock (HET) mice were assigned to one of four groups defined by a 2 X 2 factorial in which the only available drinking fluid was either lead (L) or water (C) from the time of mating to birth or from birth to the end of the experiment. Thus, a control group (CC) received water throughout, whereas the other three groups received a 0.5% lead acetate solution at the time they were mated (LC) or when pups were discovered (group CL), or throughout the experiment (group LL). The effects of these exposure regimes on activity were assessed in an open field or a running wheel when the mice were 25 days of age and then again when they were 55 days old. Aspects of agonistic behavior were also examined in these animals. Mice that received lead only following birth (CL group) appeared most affected in the open field and in running wheels. But, both the direction and degree of this effect were influenced by the specific test situation and measures as well as by the age of the mouse when tested. For example, the CL group crossed the most squares in the open field at both ages. However, the CL group was less active during their first day in the running wheels when 25 days old, but not when 55 days old. In general, activity of the LC group was least affected by administration of lead, but the effects of continued exposure to this toxic substance (LL group) were not simply additive. In contrast to measures of activity, agonistic testing at 60 days of age showed that all groups that had been or were being exposed to lead (CL, LC, LL) displayed a shorter latency to fight when compared to the control group (CC).