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Property of thimerosal-induced decrease in cellular content of glutathione in rat thymocytes: a flow cytometric study
T Ueha-Ishibashi1, T Tatsuishi, K Iwase
1Laboratory of Cellular Signaling, Faculty of Integrated Arts and Sciences, The University of Tokushima, Minami-Jyosanjima 1-1, Tokushima 770-8502, Japan.
Summary
Thimerosal, a vaccine preservative, reduced glutathione in rat cells in a dose-dependent manner. L-cysteine mitigated these effects, suggesting low in vivo risk due to typical thimerosal exposure levels.
Area of Science:
- Biochemistry
- Toxicology
- Immunology
Background:
- Thimerosal is a mercury-containing preservative used in vaccines.
- Concerns exist regarding potential adverse health effects of thimerosal on infants.
Purpose of the Study:
- To investigate the impact of thimerosal on cellular glutathione levels.
- To assess thimerosal's cytotoxic effects on thymocytes.
Main Methods:
- Rat thymocytes were treated with varying concentrations of thimerosal.
- Cellular glutathione content was measured using flow cytometry and 5-chloromethylfluorescein diacetate.
- Apoptosis and intracellular calcium were also assessed.
Main Results:
- Thimerosal reduced glutathione in a concentration-dependent manner, with complete depletion at 30 microM.
- L-cysteine treatment attenuated thimerosal's effects on glutathione and calcium.
- Prolonged thimerosal exposure induced apoptosis, and its cytotoxicity was enhanced by oxidative stress.
Conclusions:
- Thimerosal depletes cellular glutathione and can induce apoptosis in thymocytes.
- L-cysteine may offer protection against thimerosal's cellular effects.
- In vivo risks are likely low given typical vaccine thimerosal concentrations and blood thiol levels.