Statistical data showing the acute and chronic effects of HgCl
on cell viability of developing and mature cortical network. A. To evaluate the effect of HgCl2 on neurite initiation and network formation during the early stage of neuronal development, rat cortical cells were cultured in the absence (control) or presence of HgCl2, at 25 nM, 100 nM, and 25 μM, for 3 days. Cell viability/cytotoxicology assay were performed on day 3. The number of live and dead cells in randomly chosen areas of 1 mm2 was counted. The percentage of live cells is presented in the bar graph. These data show that cultures in the presence of HgCl2 at 25 μM, but not 25 or 100 nM, exhibited significant reduction of cell viability. B. To evaluate the acute effect (< 24 hrs) of HgCl2 exposure on the newly developed network, 4 day old cortical cultures were exposed to HgCl2, at 25 nM, 100 nM, and 25 μM, for 16 to 24 hrs. Subsequent live/dead cell assay showed that acute exposure to higher concentration of HgCl2 at 25 μM significantly reduced the cell viability. C. To evaluate the chronic effect (7 days) of HgCl2 exposure on the neuronal network, cells were grown for 10 days and were maintained for another 7 days in the absence or presence of HgCl2. Phase contrast images of neurons in the same area of 0.33 mm2 were taken on day 10 and day 17. The statistic data show that the numbers of neurons were significantly reduced by exposure to HgCl2 for 7 days at all concentrations examined. Statistical significance was determined using ANOVA (A &B) and Student’s paired t-test (C). Post hoc analysis was conducted using Tukey’s test. ** P < 0.01. *** P < 0.001. Error bars indicate SEM for all figures.