Fatty acyl-CoA oxidase in rat kidney and liver after application of thyroxine

Male rats were fed a standard diet containing 2.5 mg% L-thyroxine. After 10 and 20 days, in postnuclear fractions of the kidney the specific activity of fatty acyl-CoA oxidase, the enzyme responsible for the rate-limiting first step of peroxisomal fatty acid beta-oxidation, was increased by 100 and 160%, respectively. A similar effect was found in the liver. It is suggested that thyroxine essentially affects only this step of the fatty acid beta-oxidation sequence. Presumably the elevation of fatty acyl-CoA oxidase is one reason for the beneficial action of thyroid hormones in toxic lesions of the kidney.