Oxidative stress by inorganic arsenic: modulation by thyroid hormones in rat.

Arsenic toxicity is attributed mainly to lipid peroxidation and oxidative stress. We therefore studied the modulatory effects of thyroid hormones on arsenic toxicity in rat on lipid peroxidation and oxidative stress. Thyroid hormones, through a mechanism unknown at present, inhibit arsenic accumulation in liver and kidney. Mobilization of arsenic apparently diminishes lipid peroxidation and improves reduced glutathione status, two biochemical demands of combating arsenic toxicity. Results are discussed in reference to the effect of thyroid hormones on microsomal metabolism of arsenic. Arsenic is less toxic in hyperthyroid than in hypothyroid rats. A physiological antagonism between arsenic and thyroxine is discussed.