The effect of lead on mouse brain development

Nursing C57 black or Swiss-Webster albino mother mice were given doses ranging from 0.08 to 2% of lead in food (PbCO₃) or 0.5% in drinking water (PbAc₂) and the pups were maintained on the lead diet through 60 days of age. Daily measurements of food intake, body weight, and neurological status were performed. Pups were killed at 30, 42, and 60 days of age, and the dams were killed 2 weeks after weaning. The highly inbred C57 mice only rarely raised their litters if given 0.8% lead but the less inbred albino mice accepted up to 2% lead. The dams remained well on diets of 1% and less. A dose-related retardation as high as 50% of controls in body growth, brain development, and sexual and behavioral maturation was found. Although dams fed 0.4% or more of lead ate less than control mice, retardation at the various lead doses was better correlated with lead concentration in the diet than with food consumption. Undernutrition is probably not the major cause of the retardation since varying the litter size did not greatly affect the detrimental effect of the diet. The lead mice were weaned approximately 2 weeks later than the controls. Small brain size, marked retardation of brain maturation, and retardation of bone growth characterized the lead-fed animals.