Neuropathology of the antischistosomal agent amoscanate administered in high oral doses to rats

Amoscanate is a highly effective antischistosomal agent when administered as a 5% absorbable aqueous suspension. This preparation produces lesions in the brains of young adult rats given extremely high oral doses. Lesions are confined to areas adjacent to the lateral ventricles and are dominated by necrosis of the neuropil of the medial striatum, with relative sparing of bundles of myelinated fibers in the necrotic zone. There is a striking accumulation of calcium-containing microgranules in these areas. The ependyma survives on the ventricular wall overlying the necrotic zone, but pyknosis and increased extracellular space are apparent among ependymal and subependymal cells in the region. Occasionally, fibers of the fornix are focally damaged in immediate proximity to the lateral ventricle; the corpus callosum is rarefied, and microhemorrhages also occur. It is hypothesized that high concentration of the toxic agent in ventricular cerebrospinal fluid plays an important role in pathogenesis. The neuropil of the medial striatum is selectively vulnerable.