Pathological changes occurring in nervous system were systemically examined after treatment with various drugs or chemicals. Low-dose and chronic treatment mostly produced distal axonopathy either in central nervous system (by chinoform or its related compound, 5, 7-dichloro-8-hydroxyquinoline), or in peripheral nervous system (by 2-methylaminocarbothioyl-2-(2-pyridyl) tetrahydrothiophene), or even in both (by 2, 5-hexanedione (2, 5-HD) and acrylamide (ACR)). Many of these axonopathies were characterized by accumulation of certain organella, neurofilaments by 2, 5-HD or ACR, or vesicular and tubular organelles by 2-methylaminocarbothioyl-2-(2-pyridyl) tetrahydrothiophene, while no characteristic feature was detected in the axonopathy by chinoform. High-dose and short-term treatment, on the other hand, commonly induced edematous or necrotic changes in the particular regions, such as hippocampus by chinoform, cerebellar and vestibular nuclei by 2, 5-HD or misonidazole, entopeduncular nuclei by misonidazole, and cerebellar cortex by misonidazole or ACR. It is considered necessary to find a common and diverse molecular structure or biochemical feature among many neurotoxic chemicals concerning patterns of morphologic changes in order to evaluate the pathogenesis of neurotoxicity.
