Abstract
Aim: To study bioenergetics disruption and oxidative stress as underlying mechanisms for lead induced cytotoxicity in human retinal pigmented epithelial (RPE) cells.
Methods: The cytotoxic effect of lead nitrate (Pb) on the human REP cells was evaluated by MTT assay using concentrations range 0.1-100 mu M in time points from 3-48 hours. The effect of Pb on ATP production, complexes I and III activities, Oxygen consumption rate and lactate production by the cells were evaluated using MTT estimated 1050. For oxidative stress studies, the effect of PB was on the treated cells' reactive oxygen species (ROS)production, catalase (CAT), superoxide dismutase (SOD), reduced glutathione, and lipid peroxidation was evaluated.
Results: Lead was found to be cytotoxic to the cultured HRPE cells with decreased ATP production in a concentration and exposure duration dependent patterns. Lead was found to significantly inhibits the activities of complexes I and III to about 65% and 80% of the control samples activities, respectively (P=0.0002 and 0.0024, respectively). Also, Lead was found to induce significant decrease in the treated cells OCR to about 72 % of the control OCR levels (P=0.0049) with a significant increase lactate production (p=0,004). Pb was found to significantly increase ROS production (p=0.006) with significant decrease in both CAT and SOD activities and intracellular reduced glutathione stores (p=0.0005, 0.0024, 0.003 respectively) and increased lipid peroxidation in (P=0.0052).
Conclusion: lead is cytotoxic to the retinal pigmented epithelial cells. Bioenergetics disruption and oxidative stress may play a major role in Pb induced retinal complications.