Studies on the mechanism of lithium action: preliminary report.

Preliminary observations in a small animal sample reveal that chronic lithium treatment in rats produced significant changes in the microvillous processes on the cell surface of the choroid plexus. These alterations may be associated with increased intracellular choroidal volume. The type of changes noted by SEM suggest an alteration in movement of water into the extracellular areas of the brain. This basic alteration produced by lithium in the secretory/absorptive capacity of the chorid plexus is probably reversible.