Tri-iodothyronine alters superoxide dismutase expression in a teleost Anabas testudineus

393-398The effect of tri-iodothyronine (T₃) on superoxide dismutase (SOD) expression was evaluated in a teleost Anabas testudineus (euthyroid fish) by native gel electrophoresis and Western blot analysis. SOD is an essential enzyme for the survival of oxygen-utilizing organisms. Its expression is altered by the stress, presumably due to the increase in concentration of superoxide radical in cells. Variations of thyroid hormone levels are the major physiological modulators of cellular oxidative stress. T₃ administration generates an oxidative stress, which to some extent is neutralized by the changed activity of enzymes like SOD. T₃ treatment decreased CuZn SOD density in liver and brain of A. testudineus. The activity of CuZn SOD in liver and brain was confirmed by native gel analysis. The different physiological states of thyroid influenced the CuZn SOD activity. Western blot analysis further confirmed that liver and brain CuZn SOD decreased after T₃ treatment. From these findings, it was clear that T₃ treatment in euthyroid fish created an oxidative stress condition and thyroid hormone effectively maintained antioxidant status to overcome this situation in teleosts