Pathogenesis of Lead Encephalopathy: Uptake of Lead and Reaction of Brain Capillaries

Lead entry Into the central nervous system and effects on brain metabolism were studied in immature rats. Lead 210 readily enters the brain after intravenous injection; uptake is proportional to dose. Although blood levels fall rapidly after injection, brain lead retention is prolonged and unaffected by edetic acid therapy. In individuals who ingest lead episodically, progressive accumulation in the brain can occur without detection of changes in blood. Excessive lead deposition in the brain of nursing rat pups provokes severe hemorrhagic reactions limited to the cerebellum although lead concentrations are the same as in other brain regions. A prehemorrhagic stage of lead encephalopathy could be identified in the cerebellum by monitoring brain edema. This appears to be due to capillary dysfunction and suggests that cerebellar capillaries are more vulnerable to lead than capillaries elsewhere in the brain.