Tri-iodo thyronine regulates antioxidant enzyme activities in different cell fractions through a mechanism sensitive to actinomycin D in a teleost, <i style="">Anabas testudineus</i> (Bloch)

Abstract

The present study evaluated the effects of hyperthyroid state on lipid peroxidation and antioxidant enzymes in the crude (CF), post nuclear (PNF) and mitochondrial fractions (MF) of the fish liver. The <i style="">in vivo</i> injection of T₃ (200ng) did not change the lipid peroxidation products, malondialdehyde (MDA) and conjugated dienes (CD), while actinomycin D (10mg), a potent mRNA inhibitor when administered with T₃ increased them. The antioxidant enzymes like superoxide dismutase (SOD) and catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) had an increased activity in CF and MF of hyperthyroid group to compete the increased oxidative stress, but actinomycin D partially inhibited the T₃‑ &nbsp;induced activity. SOD and CAT activities in PNF of hyperthyroid group had no change, the glutathione concentration varied depending on the GPx and GR activity. Hyperthyroidism decreased the protein content, while simultaneous administration of actinomycin D inhibited the T₃ action of elevating the protein content. The results suggest that the antioxidant defense status in <i style="">A. testudineus</i> is modulated by thyroid hormone, through an action sensitive to actinomycin D.