Assessment of Apoptosis in Thymocytes and Splenocytes from Mice Exposed to Arsenate in Drinking Water: Cytotoxic Effects of Arsenate on the Cells In Vitro

Abstract

This study provides an assessment of the level of apoptosis in thymocytes and splenocytes from mice exposed to arsenate in drinking water. To simulate the naturally occurring exposure conditions of humans, the animals were exposed to arsenate at the concentrations of 0.5, 5, and 50 mgAs/L. TUNEL method for staining of thymocytes and splenocytes isolated from the mice after 8 and 12 weeks revealed increased percentage of apoptotic cells in the exposed groups. Although statistically significant increases were observed only for the highest concentration of arsenate, the increases showed linear trend as a function of arsenate concentration in drinking water. {In vitro} experiments performed on isolated cells incubated for 24 hours with arsenate at 6.7–2000 μM showed very similar concentration-viability relationships for both cell populations (IC50 was 442 ± 15 μM and 427 ± 18 μM for thymocytes and splenocytes, respectively). Arsenate induced a concentration-dependent increase in the percentage of the cells undergoing apoptosis. At higher concentrations, apoptosis was the predominant mode of cell death. It can be speculated that proapoptotic effects of arsenate as observed in our {in vivo} study may contribute to some immunotoxic symptoms observed in people chronically exposed to arsenic in drinking water.

Keywords:

• Arsenate
• Thymocytes
• Splenocytes
• Apoptosis
• Drinking water
• Mouse

ACKNOWLEDGMENTS

The authors thank Mariola Włodarek and Barbara Pawlak for their excellent technical assistance.

Notes

*Statistically significant difference at p < 0.05.