Hexachlorophene intoxication: Characterization of myelin and myelin related fractions in the rat during early postnatal development

Neonatal rats were intoxicated with hexachlorophene in order to investigate its effect during the peak period of CNS myelin formation. The white matter showed diffuse vacuolation and splitting of myelin sheaths, but the number and sizes of myelin sheaths were not significantly reduced. Myelin and a myelin-related fraction were isolated and characterized both morphologically and biochemically from 22-day-old brains. The yield of purified myelin from hexachlorophene intoxicated rats was greatly decreased, but the composition of the myelin was normal. An abnormal "floating fraction" was recovered during myelin purification from the hexachlorophene-treated animals. This fraction was probably derived from damaged myelin sheaths, and the sum of the floating fraction plus hexachlorophene-myelin represented 88% of the yield of control myelin. The floating fraction contained myelin whorls with an altered periodicity in some areas. Single membranes and vesicular profiles were also present. With the exception of the major myelin-associated glycoprotein which was absent or greatly reduced, typical myelin constituents were present in substantial amounts in this fraction. These results suggest that the myelin glycoprotein could be particularly susceptible to degradation following hexachlorophene intoxication.