Table 3 Summary of the results.
From: In vitro biochemical assessment of mixture effects of two endocrine disruptors on INS-1 cells
Assay | Triclosan (T) | 4-tert-Octylphenol (O) | Triclosan + 4 tert-Octylphenol (Mix) | Comments |
|---|---|---|---|---|
Glucose-galactose differential cytotoxicity | Increased cytotoxicity in galactose medium indicative of potential mitochondrial toxicity | Higher IC50 in galactose than in glucose | Increased sensitivity to galactose at lower concentrations but more resistant at higher concentrations | T conforms to a potential mitochondrial toxin |
O cell death appears independent of mitochondrial involvement | ||||
Mix IC50 values are different suggestive of extra mitochondrial toxicity | ||||
Glucose uptake | Decreased glucose consumption at high concentration, increase at low concentration but not substantial compared with Blank | Consumption pattern as with T. No significant change in glucose consumption | The increased consumption relative to the blank was not substantial | T and O—no meaningful change in glucose consumption suggested cell death mechanism independent of mitochondrial function |
Mix—increased glucose consumption suggested that the combination enhances mitochondrial dysfunction | ||||
Oxidative stress | Dose dependent increase in ROS but variation high hampering statistical significance. Decreased glutathione levels corroborated ROS production | Dose dependent increase in ROS but variation high hampering statistical significance. Decrease glutathione levels corroborated ROS production | Increased ROS, but no clear dose dependency | T—significant reduction in GSH levels correlates with sustained oxidative stress |
O, Mix—Increased GSH was in response to oxidative challenge. Response not statistically significant | ||||
All treatments led to oxidative stress which may be expected as all treatments induced cell death | ||||
Annexin PI | TCS induced cell death by apoptosis | Cell death by 4-tOP was by necrosis | Mix induced cell death by apoptosis | Probably TCS and 4-tOP have different molecular targets in INS-1 cells |
Caspase 3 activation | Increase in caspase 3 activation not substantial | Increase in caspase 3 activation not substantial | Statistically significant increase in caspase 3 activation | Unlike the Mix, apoptotic cell death by TCS was not caspase mediated |
Mitochondrial mass | No substantial change in mitochondrial content at all the concentrations relative to the untreated cells | No substantial change in mitochondrial content at all concentrations relative to the untreated cells | No substantial change in mitochondrial content at all concentrations | The substantial increase in the mitochondrial mass was recorded for Mel and Etop in connection with increased ROS activity |
Mitochondrial membrane potential MMP | Significant decrease in MMP at the high concentration. only | The increase in MMP was not substantial | Significant decrease in MMP at the high concentration | Loss of MMP suggests potential mitochondrial toxin |
O, cell death independent of mitochondrial function, correlates with necrotic cell death | ||||
Robust decrease in MMP at higher concentration suggests possible synergistic interaction or secondary effect such as apoptosis. Caspase and mitochondrial toxicity in galactose medium seem to support apoptosis rather than a direct mitochondrial effect | ||||
Intracellular calcium levels | The reduction in glucose stimulated intracellular calcium flux was not substantial | No significant changes in glucose stimulated intracellular calcium levels | Reduction in glucose stimulated intracellular calcium flux at lower concentration though not substantial | T: Decreased efficacy of glucose stimulated intracellular calcium correlates with mitochondrial dysfunction as observed for MMP and glucose consumption data |
O: No significant effect on glucose stimulated calcium influx, however a significant increase in cellular calcium was evident in the absence of glucose which may influence the reliability of this data | ||||
Mix: Data does not correlate directly with that observed for MMP and glucose consumption. A complex interaction. Diazoxide and Glibenclamide significantly increased intracellular Calcium flux |
