Omega 3-lipid peroxides injure CaCo-2 cells: relationship to the development of reduced glutathione antioxidant systems.
OBJECTIVE
Dietary polyunsaturated fats are significant sources of luminal lipid hydroperoxides whose accumulation can be injurious to the intestinal epithelium. The current study examines the cytotoxicity of peroxidized fish oil to CaCo-2 cells.


METHODS
Chromate release from cells was used as an index of CaCo-2 injury, and day 1 and day 7 postconfluent monolayers were used to represent the immature and mature states, respectively.


RESULTS
Air oxidation of fish oil yielded equimolar quantities of hydroperoxyeicosapentaenoic (20:5) and docosahexaenoic (22:6) acids. Their cytotoxicity were time- and concentration-dependent and were related to the developmental stages. A 100-mumol/L dose of hydroperoxides caused a 40% and a 15% 51Cr release from day 1 and day 7 cells, respectively. Cellular glutathione (GSH), GSH redox enzyme, and gamma-glutamyl cysteine synthetase activities were significantly lower in day 1 than in day 7 cells, indicating that hydroperoxide metabolism in immature cells is rate limited by reductant supply. GSH supplementation increased cell GSH in day 7 cells (twofold) but not in day 1 cells, suggesting a limited ability of immature cells to use exogenous GSH.


CONCLUSIONS
These results show that nondifferentiated cells are more sensitive to oxidant-induced injury than mature cells. This enhanced susceptibility is associated with a lower GSH-dependent detoxication capacity of the immature cells.
Department of Physiology and Biophysics, Louisiana State University Medical Center, Shreveport.
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D000975:Antioxidants; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D002851:Chromatography, High Pressure Liquid; D003110:Colonic Neoplasms / Q000737:chemistry / Q000378:metabolism / Q000473:pathology*; D004305:Dose-Response Relationship, Drug; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology* / Q000633:toxicity; D005395:Fish Oils / Q000494:pharmacology / Q000633:toxicity; D005954:Glucosephosphate Dehydrogenase / Q000032:analysis / Q000502:physiology; D005978:Glutathione / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D005979:Glutathione Peroxidase / Q000032:analysis / Q000502:physiology; D005980:Glutathione Reductase / Q000032:analysis / Q000502:physiology; D006801:Humans; D008054:Lipid Peroxides / Q000494:pharmacology* / Q000633:toxicity; D010084:Oxidation-Reduction; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000187:drug effects
D000975:Antioxidants; D015525:Fatty Acids, Omega-3; D005395:Fish Oils; D008054:Lipid Peroxides; D005954:Glucosephosphate Dehydrogenase; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D005978:Glutathione