The neurotoxicity of dithiocarbamates has been previously reported, however the detailed mechanism underlying the neurotoxicity is still not fully understood Among the dithiocarbamates, we investigated thiram and ziram in a neuronal-like pheochromocytoma (PC12) cells. Thiram and ziram strongly induced cell death in both dose- and time-dependent manners with the LC50 of 0.3 and 2 muM, respectively. The cell death showed typical apoptotic features, such as DNA fragmentation and an increase of subdiploidy nuclei. Interestingly, both thiram and ziram induced rapid and sustained increases of intracellular Ca2+ in PC12 cells, which were almost completely blocked by flufenamic acid (FFA), an inhibitor of non-selective cation channel. BAPTA-AM, an intracellular Ca2+ chelator inhibited the thiram- and ziraminduced apoptotic cell death. These results suggest that thiram and ziram induce apoptotic neuronal cell death by Ca2+ influx through non-selective cation channels. The present study may provide a clue for understanding the mechanism of neurotoxicity of thiram and ziram. (C) 2003 Published by Elsevier Science Inc