Rapid and sensitive neurotoxicity test based on the morphological changes of PC12 cells with simple computer-assisted image analysis

In order to develop a rapid and sensitive bioassay for the screening of che micals with possible neurotoxicity, a computer-assisted simple image-analys is system was developed to quantify small changes In the specific morpholog y of the cultured pheochromocytoma cell Line, PC12. This cell forms a neuro nlike microfibril network (neurites) in response to a nerve growth factor ( NGF) stimulation in vitro. Dichrolvos (DDVP) and methylmercury chloride (MM C) were employed as model neurotoxicants. In DDVP treatment, there was no l arge difference in the ED(50)s (effective dose that reduces the morphologic al index by 50%) among the toxicities determined from various morphological indices, but they were significantly lower than those observed by whole-ce ll-area-based toxicity assay using the hepatoblastoma cell line, Hep G2. In contrast, in MMC treatment, neurite-length-based toxicity was observed as early as 2 h, and at 48 h this was lower by over three orders of magnitude compared with whole-cell-area-based one (2.06 x 10(-7) mM vs. 6.42 x 10(-4) mM). These results demonstrate that the developed bioassay using image ana lysis of nerve-tissue-derived cell morphology allows us to screen possible neurotoxic chemicals very rapidly with highly enhanced sensitivity, particu larly for some chemicals that preferentially act on nerve fibers.