In a new study, researchers have established how exposure to lead during early brain development in children can damage it.
They found that exposure to lead during the formation of synapses alters the levels of several key proteins involved in neurotransmitter release.
Effective brain function depends on the efficient signalling from one neuron to the next, a process that depends on a quick release of neurotransmitters at synapses.
It was known that during a child's early brain development, exposure to lead during synaptogenesis affects the release of these critical neurotransmitters but the reason was unclear.
Tomas Guilarte, chair of Environmental Health Sciences at Columbia University's Mailman School of Public Health suggests that these changes are mediated by the inhibition of the N-methyl-D-aspartate receptor (NMDAR), disrupting the release of the trans-synaptic signaling neurotrophin, brain-derived neurotrophic factor (BDNF).
During early brain development, packets of pre-assembled proteins arrive at presynaptic active zones (PAZ), which are highly specialized regions designed to provide fast efficient neurotransmitter release. Disruption of this normal developmental process can impair brain function throughout life-as is the case with early lead exposure.
"What this work shows is that we are beginning to understand a comprehensive mechanism by which lead exposure alters the basic molecular biology of brain synapses," says Guilarte, who is also Leon Hess Professor of Environmental Health Sciences.
"Our results are the first to explain precisely how the vesicular release of neurotransmitters is impaired."
The study appears in the current issue of Toxicological Sciences.