Effects of meso-2,3-dimercaptosuccinic acid on methylmercury-injured human fetal astrocytes in vitro

Adenine nucleotides in cultured brain cells after exposure to methyl mercury and triethyl lead

To obtain more information on the biochemical background, of methyl mercury (MeHg) and triethyl lead (Et3Pb) toxicity, the doses which were needed to alter the cellular content of adenine nucleotides were compared to doses which induced morphological alterations. Three-week-old cultures of brain cells from new-born rat were incubated for 5-60 min. with 28, 16, and 8 X 10(-6) M MeHg or with 3 X 10(-6) M Et3Pb in the nutrition medium. MeHg at 28 and 16 X 10(-6) M simultaneously changed the cell shape and reduced both the cellular content of adenine nucleotides and the relative level of ATP. In cells treated with 16 X 10(-6) M MeHg, a cellular increase in inosine and hypoxanthine and an unaltered content of adenine nucleotides in the nutrition medium, points to an intracellular degradation of adenine nucleotides. Incubation with 8 X 10(-6) M MeHg during the first hour of incubation, did not change the content of adenine nucleotides, however, MeHg induced a slowly progressing degeneration of cellular extensions. 3 X 10(-6) M Et3Pb induced morphological alterations but no changes in cellular nucleotide levels. The results show that morphological alterations occur in MeHg and Et3Pb treated cultures at concentrations of the compounds which are too low to change the content and composition of cellular adenine nucleotides.

Surface charge alterations in mouse fetal astrocytes due to methyl mercury: an ultrastructural study with cationized ferritin

A brief exposure of low dose methylmercuric chloride to monolayer cultures of mouse fetal astrocytes caused a marked shift in the distribution of anionic groups on the surface membrane as evidenced by irregular disruption of cationized ferritin. It is suggested that one of the earliest changes following methyl mercury exposure in embryonic astrocytes includes alterations in the surface charge which may in turn trigger cascading toxic actions of methyl mercury in the developing brain.

The comparative effects of methylmercuric chloride and mercuric chloride upon DNA synthesis in mouse fetal astrocytes in vitro

The relative effects of direct exposure to methylmercuric chloride (MMC) and mercuric chloride (MC) upon [3H]thymidine incorporation were determined using cultured mouse fetal astrocytes. The labeling indices of cells exposed to MMC were significantly lower than those of cells exposed to equimolar concentrations of MC. These results indicate that on a mole-for-mole basis, MMC is much more deleterious upon DNA synthesis of mouse fetal astrocytes than those of MC.

Differential responses to methylmercury exposure and recovery in neuroblastoma and glioma cells and fibroblasts

The effects of methylmercury (MeHg) on cytoplasmic microtubules in cultured neuroblastoma cells, glioma cells, and fibroblasts were compared. Neuroblastoma cells appeared to be more sensitive to disruption of microtubules by MeHg than the glioma cells or fibroblasts; cellular concentrations of mercury after MeHg were also higher in neuroblastoma cells. Recovery of microtubule structure was monitored in cells after removal of MeHg; addition of the chelating dimercaptosuccinic acid (DMSA) increased reassembly of microtubules. During MeHg treatment and early recovery, microtubule integrity was dependent on cellular mercury concentrations. However, after prolonged DMSA exposure, mercury appeared to reenter the cell, without causing dissociation of microtubules.

Interaction of methylmercury with microtubules in cultured cells and in vitro

The effects of methylmercury (MeHg) on cytoplasmic microtubules in cultured fibroblasts and on the in vitro polymerization of microtubules were examined. MeHg caused disruption of cellular microtubules in a concentration- and time-dependent manner. Addition of the metal-chelating agent, dimercaptosuccinic acid (DMSA), both prevented and reversed the effect of MeHg. Comparisons of the cellular levels of mercury and microtubule integrity indicated that microtubules dissociated at levels higher than 0.6 microgram Hg/mg protein. In vitro polymerization was also directly inhibited by MeHg; this effect was prevented by the addition of DMSA.