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THE ORGANOPHOSPHOROUS INSECTICIDE FENTHION DOES NOT AFFECT PHAGOCYTOSIS OF ROD OUTER SEGMENTS BY RETINAL PIGMENT EPITHELIUM CELLS IN CULTURE.
Citation:
Geller, A M. AND L. Sutton. THE ORGANOPHOSPHOROUS INSECTICIDE FENTHION DOES NOT AFFECT PHAGOCYTOSIS OF ROD OUTER SEGMENTS BY RETINAL PIGMENT EPITHELIUM CELLS IN CULTURE. Presented at Society of Toxicology, New Orleans, LA, March 06 - 10, 2005.
Description:
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Exposure to the organophosphorous insecticide fenthion has been associated with retinal degeneration in occupational studies. It has also been associated with pigmentary changes of the retina. Because retinal degeneration and pigmentary changes may be due to dysfunction of the retinal pigment epithelium (RPE) at the back of the eye, we tested RPE cell function and viability with exposure to fenthion. Human-derived RPE cells, ARPE-19, were grown to confluence in 12 well plates. Cells were exposed for 24 hours to 10-7 - 10-5 M fenthion, a range of concentrations that has been shown to affect cell viability and function in other neurally-derived cell lines. Cell viability was assayed with a propidium iodide/calcein live/dead (L/D) assay. The ability of the RPE cells to phagocytize rod outer segments (ROS), one of the important homeostatic functions of the RPE, was tested by co-incubating the cells with ROS labeled with fluorescein isothiocyanate, then evaluating them with fluorescent phase microscopy. Phagocytosis was also evaluated under conditions that enhance (incubation with insulin) or inhibit this function (incubation in cold or in serum-free medium). ARPE-19 cells showed no decrease in viability after treatment with 10-7 - 10-5 M fenthion. Positive control experiments with hydrogen peroxide demonstrated the sensitivity of the L/D assay. This concentration range of fenthion also had no notable effect on phagocytosis of ROS. Phagocytosis could be enhanced by incubation with insulin or inhibited by cold or incubation in serum-free medium. Exposure to the OP fenthion did not produce dramatic effects on RPE cell viability or their ability to phagocytize ROS. Further work will establish the sensitivity of these cells to the oxon metabolite of fenthion. ARPE-19 cells appear to be less sensitive than neuroblastoma and PC-12 cells to the effects of fenthion. This abstract does not reflect US EPA policy.