Perinatal exposure to lead induces morphological, ultrastructural and molecular alterations in the hippocampus

Area of Science:

• Neuroscience
• Toxicology
• Developmental Biology

Background:

• Lead (Pb) exposure during development is a significant public health concern.
• Understanding the impact of low-level lead exposure on the developing brain is crucial for cognitive health.
• Apoptosis and necroptosis are critical cell death pathways affected by neurotoxicants.

Purpose of the Study:

• To investigate the effects of pre- and neonatal lead exposure on apoptosis and necroptosis in the developing rat brain.
• To determine if low-level lead exposure alters neuronal cell death pathways and brain structure.
• To examine the impact on specific brain regions like the forebrain cortex, cerebellum, and hippocampus.

Main Methods:

• Pregnant rats and their offspring were exposed to lead acetate in drinking water.
• Analyzed Caspase-3 activity, AIF translocation, DNA fragmentation, Bax/Bcl-2 expression, and BDNF levels.
• Utilized microscopic examination and molecular analysis in specific brain regions (forebrain cortex, cerebellum, hippocampus).

Main Results:

• Lead exposure at levels below 10 μg/dL reduced hippocampus neuron count and caused ultrastructural alterations.
• No significant evidence of severe apoptosis or necrosis (e.g., active Caspase-3, AIF translocation) was observed.
• Reduced levels of Brain-Derived Neurotrophic Factor (BDNF) were noted, alongside a potentially protective decrease in the Bax/Bcl-2 ratio.

Conclusions:

• Neonatal lead exposure, even at sub-threshold levels, can lead to a reduction in hippocampus neurons and structural changes.
• The developing brain may exhibit resilience against severe apoptosis/necrosis, but subtle neurodevelopmental impacts occur.
• Further research is needed to elucidate the role of the Bax/Bcl-2 ratio in mitigating lead-induced neurotoxicity.