Morphological changes in the optic nerve after chronic exposure of neonatal rats to cocaine and amphetamine.

We determined the effects of cocaine hydrochloride (15 mg/kg body weight/day) or amphetamine sulfate (25 mg/kg body weight/day) on the optic nerve in groups of rats exposed from postnatal day 1 to 30. Qualitative and quantitative studies of cross-sections of the optic nerves showed different patterns of organization, namely the presence of degenerative features in drug-treated animals and significant differences in the proportion of the nerve occupied by glial cells and their processes and nerve fiber bundles. No significant differences of the total number of fibers were found. Taken together, these data indicate that the optic nerve is vulnerable to early exposure to cocaine and amphetamine which cause developmental changes in this link of the visual pathways.