Selective vulnerability of the developing brain to lead

Environmental lead exposure in young children who ingest household paint du st or other sources impairs their potential intelligence in a linear, dose- dependent fashion in contrast to its far more subtle effects on other neuro logic functions. Basic investigations have identified three interrelated st eps in synaptic neurotransmission at which low levels of lead can disrupt s ignal processing. Lead enhances background transmitter release, but impairs stimulated release, inhibits function at the N-methyl-D-aspartate-type glu tamate receptor and stimulates background levels of the intracellular messe nger protein kinase C. Taken together these effects have the effect of dimi nishing the synaptic signal to noise ratio. The ability of lead to enhance 'synaptic noise' during a critical early period of postnatal development ma y permanently disrupt the architecture of cortical processing units by depr iving them of high resolution environmental signals needed to refine synapt ic connections. Curr Opin Neurol 11:689-693. (C) 1998 Lippincott Williams & Wilkins.