Effects of chloroquine on the ependyma, choroid plexus and epiplexus cells in the lateral ventricles of rats

1-day-old postnatal rats were given daily intraperitoneal injections of chloroquine for 6 successive days and sacrificed at 7, 14 and 21 days of age. In rats killed at 7 and 14 days of age, the choroid plexus epithelial cells and ependymal cells lining the lateral ventricles showed a marked increase in number and size of lysosomes; some cells were extremely vacuolated. The epiplexus cells associated with the choroid plexus were also affected showing numerous vacuoles and lamellar bodies. Furthermore, their immunoreactivity with the antibodies OX-42, OX-18, OX-6 and EDI were augmented when compared with cells in the control rats. At 21 days of age the ultrastructural features of the various cell types in the chloroquine-injected rats resembled those in the corresponding control rats. The immunoreactivity of epiplexus cells was also comparable in the two groups of animals at this time point. It is concluded from this study that although chloroquine induces acute structural alterations of choroid plexus epithelial cells, ependymal cells and epiplexus cells, its effects are reversible since the cells regained their normal ultrastructure and immunohistochemical features following the discontinuation of the drug.