Exposure to
mercury can lead to several
injuries in mammals, including immune system dysfunction, and
pyrrolidine dithiocarbamate (
PDTC), as a
metal chelator and
antioxidant, has been indicated to increase the cytotoxic effects of toxic metals. However, the toxicological effects and possible mechanisms of
mercury in combination with
PDTC are mostly unclear. In this study, we showed that
PDTC dramatically increase the cytotoxic effect of HgCl(2) on cultured murine macrophages (RAW 264.7 cells).
PDTC augmented HgCl(2)-induced cytotoxic effects by facilitating the entry of
mercury into the cells. The Hg(2+)/
PDTC complex significantly and rapidly increased the formation of
reactive oxygen species (ROS) and decreased intracellular
glutathione (GSH) levels in these cells. Flow cytometry analysis showed that the numbers of sub-G1 hypodiploid cells and
annexin V-FITC binding cells increased after Hg(2+)/
PDTC complex exposure, and several features of mitochondria-dependent apoptosis were also induced, including mitochondrial membrane depolarization, cytosolic
cytochrome c release,
poly(ADP-ribose) polymerase (PARP) and
caspase 3/7 activation, and DNA fragmentation. Moreover, both apoptotic and necrotic cells were detected using
acridine orange/
ethidium bromide dual staining. Meanwhile, depleted intracellular
ATP levels and increased
lactate dehydrogenase (LDH) release were observed, suggesting the induction of necrotic cell death processes. These Hg(2+)/
PDTC complex-induced cytotoxicity-related signals could be reversed by pretreatment with the
antioxidant N-acetylcysteine. In conclusion, these results suggest that Hg(2+)/
PDTC complex-induced oxidative stress causes macrophage cell death via both apoptosis and
necrosis. These findings imply for the first time that
PDTC dramatically increases the uptake and toxicological effects of Hg(2+) instead of detoxification.