Effect of perinatal lead exposure on rat behaviour in open-field and two-way avoidance tasks

In view of conflicting results in literature concerning lead exposure associated with behavioural alterations, this study investigated behaviour in the open-field and shuttle avoidance, for as well as tissue lead burdens of pre- and postnatally lead-exposed rats. Rats were exposed to the metal from conception to weaning by giving the dams 0.5, 2.0 or 4.0 mM lead acetate in drinking water. This regimen did not affect body weight gain of dams or offspring development and had no effect on cerebral weights nor on haematological parameters of 23-day-old rats. In 1-day-old rats, lead accumulated in the blood but not in the brain, whereas both in 23-day-old rats and in dams lead accumulated in blood, kidney and cerebral cortex. In the open-field, lead-exposed groups showed higher locomotor activity in the test session as compared to controls and did not show any decrease in rearing responses in the test, indicating less habituation. Lead-treated rats subjected to a shuttle avoidance task showed no significant increase in avoidance responses between sessions as compared to control, indicating less retention. Moreover, only the control group presented a significant reduction of the footshock escape latency along testing session, suggesting a lead effect on footshock escape acquisition. In the shuttle box, intertrial crossing responses were not affected by lead treatment. The behavioural alterations occurred in animals with blood lead levels in the range 11-50.6 micrograms/dl.