Effect of gold nanoparticles on superoxide dismutase and indoleamine 2, 3-dioxygenase in various rat tissues.

Gold nanoparticles have diverse applications and are being used in food and cosmetic industry, for drug delivery and in the diagnosis and treatment of cancer. However there is a need to study their biochemical mode of action. In this study, in vivo effect of gold nanoparticles on the activities of the two antioxidant enzymes -superoxide dismutase (SOD) and indoleamine 2,3-dioxygenase (IDO) was investigated in various tissues of rats. Rats were injected with 20 microg/kg body wt of 20 nm gold nanoparticles for three consecutive days through intraperitoneal route. The animals were sacrificed by CO2 asphyxiation 24 h after the last dose of gold nanoparticles. Results showed that treatment with gold nanoparticles caused no significant change in SOD activity in most of the tissues, except kidneys. In kidneys, gold nanoparticles caused a significant increase in SOD activity, when compared to the activity in control rats. However, treatment with gold nanoparticles altered the expression pattern of SOD activity in various tissues. For example, in control rats highest SOD activity was demonstrated in heart and least in kidneys and spleen. But, in gold nanoparticles treated rats, maximum SOD activity was observed in liver and the lowest in spleen. Gold nanoparticles caused no significant change in IDO activity in the studied tissues.