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

Abstract

The responsiveness of the adult toad to triiodothyronine (T3) and thyroxine (T4) was studied by measuring the mitochondrial alpha-glycerophosphate dehydrogenase activity and mitochondrial protein content of liver, muscle and brain of toad. Both T3 and T4 increased the alpha-GPD activity and mitochondrial protein content of liver and muscle of toad. The extent of increase in the alpha-GPD activity and mitochondrial protein content were more pronounced with T3 than with T4. Further that the muscle exhibited more alpha-GPD activity than liver, whenever liver showed greater mitochondrial protein content than that of muscle. Brain showed no significant change in the alpha-GPD activity and mitochondrial protein content. Injections of cycloheximide showed inhibition of T3 induced changes in liver and muscle. Injection of propylthiouracil also counteracted the T4 induced effects of liver and muscle.

Influence of Chronically Altered Thyroid Status on the Activity of Liver Mitochondrial Glycerol-3-phosphate Dehydrogenase in Female Inbred Lewis Rats

“…Thyroid hormones especially induce a considerable increase in GPDH activity in the liver [3 ± 5]. As in mammals, toad liver showed GPDH responsiveness to both thyroxine (T 4 ) and triiodothyronine (T 3 ) [6]. Lee and Lardy [3] showed that feeding 2 % desiccated thyroid gland mixed with laboratory chow for 10 days in-creased the activity of rat liver GPDH by up to twenty times control values.…”