Brain biochemistry of infant mice and rats exposed to lead

Rats receiving 1% of lead in the diet from birth were studied from an age of 0.5 to 12 months. In a preliminary experiment, mice given 0.1 or l mg/ml of lead in the drinking water were followed up to 1 month. The following parameters in brain were investigated. DNA, protein, OH-proline, sialic acid, lipids, cathepsin D, β-glucuronidase, acid phosphatase, δ-aminolevulinic acid dehydratase (ALAD), peroxides and peroxidation, serotonin, noradrenaline, dopamine, histamine, uptake of α-amino isobutyrate (AIB) and blood flow on the basis of 15 μm muspheres captured. Blood flow and AIB uptake were also studied in other organs. The most important findings in mice were, a retardation in body growth and development in brain DNA, a decrease in brain ALAD and sialic acid and a decrease in AIB uptake by brain. In rats, cathepsin was enhanced at almost all times, OH-proline increased from 4 months, peroxides and peroxidation increased in many samples. A raise in serotonin and - when all samples were considered together - in noradrenaline was also noted. AIB uptake by brain and particularly by kidney was decreased whereas brain blood flow increased. The observations suggest an important role of proteolytic processes and biogenic amines in lead encephalopathy.