Stimulation of oxidative metabolism by thyroid hormones in an apodan amphibian, Gegenophis carnosus (Beddome).
Administration of different doses of L-thyroxine (T4) and triiodo-L-thyronine (T3) in vivo in G. carnosus stimulated the activities of cytochrome oxidase, alpha-glycerophosphate dehydrogenase (alpha-GPDH), succinate dehydrogenase (SDH), and Mg2+ adenosine triphosphatase (Mg2+ ATPase) and inhibited the activity of malate dehydrogenase (MDH). While a low dose of thiouracil administration produced a stimulatory effect on cytochrome oxidase and alpha-GPDH activities, a higher dose of thiouracil significantly inhibited the activities of cytochrome oxidase, alpha-GPDH, SDH, Mg2+ ATPase, and MDH. Injection of T4 or T3 into thiouracil-treated animals significantly restored the stimulatory effect of thyroid hormones on oxidative enzyme activities. It is suggested that thyroid hormones in vivo increase and that thiouracil decreases the oxidative capacity of hepatic mitochondria of G. carnosus.
Sutharam
K K
KK
Department of Zoology, University of Kerala, Trivandrum, India.
Peter
M C
MC
Oommen
O V
OV
D000663:Amphibians / Q000378:metabolism*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors / Q000378:metabolism; D005260:Female; D005993:Glycerolphosphate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology*; D010084:Oxidation-Reduction; D013385:Succinate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013889:Thiouracil / Q000008:administration & dosage / Q000494:pharmacology; D013974:Thyroxine / Q000008:administration & dosage / Q000494:pharmacology*; D014284:Triiodothyronine / Q000008:administration & dosage / Q000494:pharmacology*
D014284:Triiodothyronine; D013889:Thiouracil; D005993:Glycerolphosphate Dehydrogenase; D008291:Malate Dehydrogenase; D013385:Succinate Dehydrogenase; D003576:Electron Transport Complex IV; D017301:Ca(2+) Mg(2+)-ATPase; D013974:Thyroxine