Thyroid hormone-inducible monoamine oxidase inhibitor in rat liver cytosol.
An endogenous inhibitor of monoamine oxidase (MAO) was separated by gel-filtration from 105,000 g supernate of T4-treated rat liver cytosol. The inhibition by this inhibitor was concentration-dependent and more potent for A-form MAO than for B-form MAO. The mode of inhibition was competitive either with 5-hydroxytryptamine or beta-phenylethylamine. The molecular weight of this inhibitor was estimated to be 600-700 by gel filtration. The pI value was determined to be 3.0 by isoelectric focusing. This inhibitor was proved to be heat-stable and resistant to protease treatment. MAO inhibition activity was much lower in the cytosol of thyroidectomized, non-T4-treated rats than T4-treated rats, suggesting that this inhibitor is induced by thyroid hormone T4. MAO activity in rat liver might be regulated by the level of this inhibitor.
Obata
T
T
Department of Pharmacology, Medical College of Oita, Japan.
Tamura
M
M
Yamanaka
Y
Y
D000818:Animals; D003600:Cytosol / Q000032:analysis*; D007526:Isoelectric Point; D008099:Liver / Q000032:analysis*; D008297:Male; D008996:Monoamine Oxidase Inhibitors / Q000302:isolation & purification* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013974:Thyroxine / Q000494:pharmacology*
D008996:Monoamine Oxidase Inhibitors; D013974:Thyroxine