Teuta Murati

Lindane-induced cytotoxicity and the role of vitamin E in Chinese hamster ovary (CHO-K1) cells

Lindane, a toxic insecticide from the persistent organic pollutants (POP’s) group, may act as an endocrine disrupter affecting crucial tissues of reproductive system. In this study a Chinese Hamster Ovary cell line (CHO-K1) was applied to assess the potential of lindane cytotoxicity at the cellular level. The methods of Trypan blue exclusion, MTT and Kenacid blue assays were used to assess cytotoxicity and confirmed a decrease in the number of viable CHO-K1 cells at 34.4–344 μM lindane during 24, 48 and 72 hours of exposure. The cell proliferation tests showed significant inhibition (p < 0.025–0.001 vs control) and a progressive increase in toxicity with increasing lindane concentrations. Corresponding IC50 values were determined with each applied method. After 72 h of lindane exposure, IC50 values were 184 μM according to the Trypan blue method and 272 and 256 μM with the Kenacid blue and MTT assays, respectively. Morphological changes induced by the cytotoxicity of lindane were followed by the fluorescence microscopy and only necrotic cells were detected. Vitamin E (25 and 50 μg/mL) was used for protection of ovarian cells against lidane-induced oxidative stress damage, and lipid peroxidation was postulated as a possible mechanism of lindane toxicity. The viability of cells pre-incubated with vitamin E was significantly enhanced (up to p < 0.025) compared to the results observed in cells exposed to lindane only, but vitamin E treatment could not prevent complete lindane-induced cytotoxicity. Results suggest that vitamin E may exert a slightly protective role in cell defense against lipophilic pro-oxidant xenobiotics such as lindane.

PCB 77 action in ovary cells--toxic effects, apoptosis induction and cell cycle analysis.

Abstract Context: PCB 77 (3,3′,4,4′-tetrachlorobiphenyl), a non-ortho congener with planar configuration, has been identified as potential endocrine disrupter capable to increase the risk of reproductive and developmental failure. Objective: In the present study, in vitro PCB 77 toxic potential, apoptosis induction and cell cycle alterations were investigated to reveal direct toxic effects on ovarian cells. Methods: Chinese Hamster Ovary (CHO-K1) cell line was selected as a model system and decreased cell viability was confirmed by application of four bioassays. Cellular morphology and quantitative analysis of apoptotic, necrotic and viable cells were determined with fluorescent microscopy and cell cycle phase distributions by measuring DNA content using flow cytometry. Results: We have indicated Trypan blue exclusion assay as the most sensitive for quantifying cytotoxicity of PCB 77 in terms of IC50 values, while the results obtained by other methods pointed to a possible localized effect on the lysosomes/endosomes (Neutral red), compromised intracellular metabolic processes (MTT) and possible interferation with the rate of protein synthesis (Kenacid blue). The loss of cell viability, as a consequence of treatment with 10–100 μM PCB 77, fundamentally was due to induction of apoptosis with observed common series of specific morphological changes characteristic to apoptotic phenomenon. The level of alterations of normal cell cycle progression was low without significant changes at analyzed time intervals. Conclusion: These results indicate toxic outcomes of PCB 77 at ovarian cellular level with regard to potential direct adverse effects to female reproductive system.