Abstract

The present studies were designed to test the effects of early exposure to low doses of lead on aggressive behavior in male golden hamsters. Litters of hamsters were exposed to lead acetate (either 0 or 100 ppm) from embryonic day 8, through weaning on postnatal day 25 (P-25), until P-42. Play fighting behavior was tested on P-19 and P-20 around the developmental onset of the behavior. During the first day of testing, lead-exposed hamsters displayed less play fighting activity. However, this difference disappeared by P-20. Around the same time, lead-exposed animals were around 20% lighter than the controls, suggesting a delayed maturation in these hamsters. Blood lead levels assayed on P-42 ranged between 10 and 15 microg/dL. Aggressive behavior was tested in early adulthood (P-45) in a resident/intruder paradigm. Lead exposure affected aggressive behavior, because lead-exposed male hamsters were faster and more likely to attack and bite their intruders. These results support the possibility that early exposure to low doses of lead during development is capable of enhancing aggressive behavior in males.