Neurotoxicity in rats sub-chronically exposed to low levels of lead

Pregnant rats (for prenatal exposure), 5-day-old rats, and 5-week-old rats were exposed orally to lead acetate daily for 10 weeks. Lead values in the brain of animals from all three lead-exposed groups were similar. Brain norepinephrine (NE) and GABA levels and glutamate decarboxylase (GAD) activity were decreased, and brain glutamate (glu), glutamine + asparagine (gln/asn), and tyrosine (tyr) levels, and monoamine oxidase (MAO) activities were increased in rats prenatally or 5 days postnatally exposed to lead. Brain ammonia, alanine (ala), aspartic acid (asp), and dopamine (DA) values were not affected by the prenatal or 5-day-postnatal lead treatment. Brain uptake index (BUI) values for glu were significantly elevated in rats exposed to lead prenatally or 5 days after birth. Exposure of 5-week-old rats to lead did not affect the brain catecholamine and amino acid levels. These results suggest that the brains of young rats were more sensitive to lead exposure than the brains of adult rats, although the accumulation of lead in brain was not affected by age.