Chronic lead intoxication: Effects on developing optic nerve

The effects of chronic lead intoxication were studied by examining the optic nerves of mice given lead‐containing mother's milk from the day 1 to day 21 of life. Biochemical assays for myelin basic protein, 2′,3′‐cyclic nucleotide phosphodiesterase, and cerebroside sulfotransferase showed that the total amount of myelin produced by the lead‐exposed animals was decreased. Lead exposure did not alter the number of oligdendroglia or the relationship between axons and myelin sheaths. The hypomyelination was paralleled by a reduction in size of optic axons in the lead‐exposed animals. The data suggest that chronic exposure to lead in developing mice results in a primary effect on neurons and that hypomyelination is secondary to reduction in axon size.