Effect of Triiodothyronine and Thyroxine on Malic Enzyme Activity and Protein and Nucleic Acid Contents of Liver and Muscle of Toad,Bufo melanostictus

Effect of Triiodothyronine and Thyroxine on Mitochondrial α-Glycerophosphate Dehydrogenase Activity and Mitochondrial Protein Content of Liver, Muscle and Brain of Toad,Bufo melanostictus

“…In search of organ-wise responsiveness to thyroid hormone and as a sequel of earlier investigations on the effect of triiodothyronine and thyroxine on some enzyme systems in different organs of adult toad, the present experiments have been undertaken to show the changes in mitochondrial aglycerophosphate dehydrogenase activity and mitochondrial protein content of liver, muscle and brain after injection of triiodothyronine and thyroxine. In previous reports from our laboratory it has been indicated that thyroid hormone-induced changes in protein and nucleic acid metabolisms and NADP-dependent cytosolic malic enzyme activity in liver and muscle of adult toad occur {Ray and Medda 1974; Dey et al 1989). It was evident from the present data that T3 and T4 administration was effective in inducing the a-GPD activity and in enhancing the mitochondrial protein content of liver and muscle of toad.…”

“…Although there are informations of relative unresponsiveness of the adult amphibia to thyroid hor-mone (Gallon 1983;1985), the thyroid gland of such unresponsive adult frog can synthesize thyroxine (T4) and triiodothyronine (T3) {Leloup and Fontaine 1960; Ceusters, Darras and Kuhn 1978), and increase in oxygen consumption has been found after T4 administration to frogs and toads acclimated above 20 °C {McNabb 1969;May and Packer 1976) and also in isolated liver slices from these animals (Packard and Packard 1973;1975). In an earlier report from our laboratory, the changes in protein and nucleic acid metabolism in adult toad liver and muscle after T4 treatment have been shown (Ray and Medda 1974), and recently we have also reported the responsiveness of adult toad to T3 and T4 with respect to the increase in the activity of NADP-dependent cytosolic malic dehydrogenase in liver and muscle, suggesting the possible role of thyroid hormone in the metabolism of adult toad (Dey, Dasmahapatra, Ray and Medda 1989). Accordingly the changes in the activity of mitochondrial a-glycerophosphate dehydrogenase and mitochondrial protein content of liver, muscle and brain of adult toad Bufo melanostictus, after T3 and T4 treatment are reported in this communication which support the involvement of thyroid hormone in the metabolism of some specific organs.…”

“…Some toads also received propylthiouracil (PTU, Sigma Chemical Company, USA) injections at the dose of 10 ug/g with and without T4 (1 ug/g) for six consecutive days, the injection was started two days before the first T4 injectionsi. e.,on days -2,-1,0, l,2and3.The T3 group of animals were sacrificed on day 3 and the T4 group on day 4 after hormone injection as followed earlier (Dey et al 1989).…”

L-Thyroxine (T4) Elevates the Free Amino Acid Pool of Haemolymph Plasma of Tasar Silkworm, Antheraea mylitta Drury (Lepidoptera: Saturniidae)

“…Thyroid hormone elevates the level of FAA in the liver of gold fish, Carassius auratus (Thornburn and Matty 1963). Thyroxine being a vertebrate hormone is naturally responsible for various metabolic events in different vertebrates (Barsano and DeGroot 1983;De, Ray and Medda 1988;Dey, Dasmahapatra, Ray and Medda 1989;Dasmahapatra, Ray and Medda 1990). However, its involvement in silkworm life processes has created a new chapter to be explored concerning how this vertebrate hormone alone influences a number of metabolic processes in different organs of invertebrates without thyroid.…”