Tri-n-butyltin delays the cell death induced by hydrogen peroxide in rat thymocytes

Abstract Tri- n -butyltin (TBT), one of environmental pollutants accumulated in mollusks, at nanomolar concentrations decreases cellular content of glutathione (GSH), suggesting that TBT increases cell vulnerability to oxidative stress because GSH has a role in catabolizing hydrogen peroxide (H 2 O 2 ). In order to examine this possibility, the effect of tri- n -butyltin chloride (TBTCl) on rat thymocytes suffering from oxidative stress induced by H 2 O 2 was examined using a flow cytometer with four fluorescent probes; ethidium bromide, 2′,7′-dichlorofluorescin diacetate, 5-chloromethylfluorescein diacetate and annexin-V-FITC. TBTCl at concentrations ranging from 100 nM to 1 μM attenuated H 2 O 2 -induced decrease in cell viability in a dose-dependent manner. It was unlikely that TBTCl reduced H 2 O 2 -induced oxidative stress because TBTCl failed to affect H 2 O 2 -induced oxidation of intracellular molecule (2′,7′-dichlorofluorescin) and H 2 O 2 -induced decrease in cellular content of GSH. Results suggest that TBTCl may inhibit the pathway of cell death induced by H 2 O 2 or that TBTCl may induce a protective substance against the oxidative stress produced by H 2 O 2 .