3,5,3'-Triiodothyronine (T3) and 3',5'-Diiodothyrone (T2) Have Short-Term Effects on Lipid Metabolism in a Teleost Anabas testudineus (Bloch): Evidence From Enzyme Activities

Abstract

As thyroid hormones are known to have long-term and short-term effects on metabolism and only the long term effects been examined in detail, in the present investigation a comparative study has been mad to elucidate the short-term effects of T₃ and T₂ on enzymes of lipid metabolism in a fish Anabas testudineus. The time dependent studies involved assays of specific, activities of lipogenic enzymes and membrane ATPase- Anabas responded to T₃ treatment with a significant increase in the liver malic enzyme activity (after 1 hr) and the activity pattern was reversed after 6 hrs in low dose (0.25µg T₃) treated group. T₂ treatment also increased the malic enzyme activity within one hour after administration. T₂ caused an Increase, in the activity of glucose-6-phosphate dehydrogenase under both time courses, HMG-CoA Reductase activity was reduced upon T₃ and T₂ administration except for T₂ at one hour. T₃ treatment significantly enhanced Na⁺K⁺-ATPase activity while T₂ decreased it except by low dose at one hour. Both T₃ and T₂ treatment influenced the activities of enzymes of lipid synthesis in a dose and time dependent manner emphasising a short-term effect of these thyroid hormones in Anabas.