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Published on: June 28, 2024
Changes in antioxidant defense systems induced by thiram in V79 Chinese hamster fibroblasts
E Grosicka-Maciag1, D Kurpios, H Czeczot
1Department of Biochemistry, Medical University of Warsaw, 02-097 Warszawa, Banacha 1, Poland.
Abstract:
The role of antioxidant defence systems in protection against oxidative damage of lipids and proteins induced by fungicide thiram during in vitro exposure was investigated in cultured Chinese hamster V79 cells with normal, depleted, and elevated glutathione (GSH) levels. We analyzed the catalytic activities of superoxide dismutases (SOD1 and SOD2), Se-dependent and Se-independent glutathione peroxidases (GSH-Px), glutathione reductase (GR), and catalase (CAT), as well as total glutathione/glutathione disulfide ratio (GSH(total)/GSSG). Thiram treatment resulted in an increase in activities of SOD1, Se-dependent GSH-Px, and GR at the highest tested dose (150 microM). On the contrary, inhibition of CAT and Se-independent GSH-Px activities, and no significant changes in the level of SOD2 activity was observed at any tested doses (100-150 microM). GSH(total)/GSSG ratio in the 100 microM thiram treated cells was not significantly changed comparing to the control, despite significant decrease of GSH total (50%). In 150 microM thiram treated cells the ratio falls to 43% of control value. Pretreatment with l-buthionine sulfoximine (L-BSO), an inhibitor of GSH synthesis, significantly enhanced decrease in CAT and Se-independent GSH-Px activities, as well as GSH(total)/GSSG ratio, and reduced Se-dependent GSH-Px activity, following exposure to thiram. Simultaneously, L-BSO pretreatment enhanced increase in SOD1 activity, and had no effect on SOD2, following thiram exposure. Pretreatment with N-acetyl cysteine (NAC), a GSH precursor, prevented enzymatic changes in CAT, Se-dependent GSH-Px, GR, SOD1 activities, and significantly decreased SOD2 activity following exposure to thiram. GSH(total)/GSSG ratio was restored to the control value. This study suggests that following the changes in antioxidant defense systems thiram can act through the production of free radicals.
Insights
The fungicide thiram induces oxidative damage by affecting antioxidant defense systems, including glutathione (GSH) levels and key enzymes like superoxide dismutases (SOD) and catalase (CAT). Thiram
Area of Science:
- Biochemistry
- Toxicology
- Cell Biology
Background:
- Fungicides like thiram can induce oxidative stress, impacting cellular components such as lipids and proteins.
- Antioxidant defense systems, involving enzymes like superoxide dismutases (SOD), glutathione peroxidases (GSH-Px), glutathione reductase (GR), and catalase (CAT), play a crucial role in mitigating oxidative damage.
- Glutathione (GSH) is a key intracellular antioxidant involved in various cellular defense mechanisms.
Purpose of the Study:
- To investigate the role of antioxidant defense systems in protecting against thiram-induced oxidative damage in cultured Chinese hamster V79 cells.
- To analyze the effects of varying glutathione (GSH) levels on cellular responses to thiram exposure.
- To elucidate the specific enzymatic activities and redox balance alterations induced by thiram.
Main Methods:
- Cultured Chinese hamster V79 cells were exposed to thiram with normal, depleted (using L-buthionine sulfoximine, L-BSO), and elevated (using N-acetyl cysteine, NAC) glutathione levels.
- Catalytic activities of SOD1, SOD2, Se-dependent and Se-independent GSH-Px, GR, and CAT were measured.
- The total glutathione/glutathione disulfide ratio (GSH(total)/GSSG) was analyzed to assess the cellular redox state.
Main Results:
- Thiram treatment increased SOD1, Se-dependent GSH-Px, and GR activities at higher doses, while inhibiting CAT and Se-independent GSH-Px.
- GSH(total)/GSSG ratio decreased significantly with thiram exposure, indicating oxidative stress.
- L-BSO pretreatment exacerbated thiram's negative effects on antioxidant enzymes and redox balance, while NAC pretreatment partially restored enzymatic activities and the GSH(total)/GSSG ratio.
Conclusions:
- Thiram induces oxidative damage in V79 cells, primarily through the production of free radicals, which alters the antioxidant defense system.
- Glutathione levels significantly modulate the cellular response to thiram-induced oxidative stress.
- The findings highlight the complex interplay between thiram exposure, antioxidant enzyme activity, and cellular redox homeostasis.