Lead, age and aggression in male mice

The impact of eleven weeks of ingestion of a 0.5% lead acetate solution on agonistic behavior of male Binghamton Heterogeneous stock mice (either 120 or 660 days of age) was examined. Similar aged mice were paired for aggression testing. Not surprisingly, younger mice, regardless of fluid history fought more vigorously than older mice. However, when mice of similar fluid history were paired together, lead ingestion decreased the latency to fight only in older mice. Regardless of their prior fighting history, when lead treated mice fought similar aged controls, the lead exposed mice in younger pairs were typically subordinate; but in older pairs, lead exposed mice were dominant. These results, coupled with extant literature concerning age-related changes in endocrine function, pituitary-adrenal activity, and lead-induced changes in hippocampal function suggest that future work directed at mechanism(s) underlying lead-induced alterations in agonistic behavior should consider life span changes in biobehavioral profiles.