Oral Exposure to the Herbicide Simazine Induces Mouse Spleen Immunotoxicity and Immune Cell Apoptosis

The authors investigated the toxic effects of simazine on mice spleen immune cells and the underlying mechanisms. Mice were given simazine at 0, 90, 200, or 400 mg/kg by gastric gavage for 3 weeks. The authors then measured immune cell proliferation and the expressions of apoptosis-related proteins (Bcl-2, Bax, Fas, and caspase-3), spleen cell intracellular [Ca2+], cellular oxidative stress level, and immune functions. After 3 weeks, mice exposed to simazine had reduced proliferation of both spleen T and B cells. The number of spleen CD4+ T lymphocytes decreased with simazine exposure, while CD8+ T cells remained unchanged. Exposure to simazine resulted in reduced immune function, higher intracellular [Ca2+], and oxidative stress. Finally, simazine induced spleen immune cells apoptosis by reducing Bcl-2, while increasing Fas and Caspase-3 level. Overall, the immunotoxicity of simazine may involve the induction of immune cell apoptosis and alterations in the immune and physiological functions of spleen cells.