Studies on the decrease of liver cytochrome P-450 content by triiodothyronine

• Published in: Biochimica et biophysica acta Vol. 1074; no. 1; pp. 172 - 177
• Main Authors: Kleiman de Pisarev, Diana L., Ferramola de Sancovich, Ana Maria, Sancovich, Horacio A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 24.05.1991; Elsevier
• Subjects: 5-Aminolevulinate Synthetase - metabolism; Aminolevulinic Acid - metabolism; Animals; Biological and medical sciences; Cell physiology; Cytochrome P-450; Cytochrome P-450 Enzyme System - metabolism; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; Heme - metabolism; Hormonal regulation; Humans; Hydroxymethylbilane Synthase - metabolism; Male; Microsomes, Liver - drug effects; Microsomes, Liver - enzymology; Molecular and cellular biology; Porphobilinogen Synthase - metabolism; Proteins - metabolism; Rat liver; Rats; Rats, Inbred Strains; Serum Albumin - metabolism; Triiodothyronine; Triiodothyronine - pharmacology; Rat liver; ALA; T 3; Cytochrome P-450; ALA-Synthase; PBGase; Triiodothyronine; T 8; Hemoprotein; Rat; Gel electrophoresis; Cytochrome P450; Liver; Rodentia; Aminoacid derivative hormone; Microsome; Vertebrata; Mammalia; Enzymatic activity; Hormonal regulation; Thyroid hormone
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/0304-4165(91)90057-N

In the rat liver, the microsomal content of cytochrome P-450 decreased by 50% after triiodothyronine (T 3) administration. The molecular basis for the decreased cytochrome P-450 levels was investigated. The activities of the enzymes involved in heme synthesis or degradation were not altered by thyroid hormone administration. The incorporation of 3H-δ-aminolaevulinate into the liver microsomal heme was markedly reduced in T 3-treated rats. The latter appeared not to reflect a lowered binding affinity of the apoprotein moiety of cytochrome P-450 for heme. The sodium dodecyl sulfate gel electrophoresis of the microsomal preparation showed a decrease in apocytochrome P-450. It is suggested that the amount of the apocytochrome may be the primary event affected in the formation of cytochrome P-450, by triiodothyronine treatment of thyroidectommized rats.