Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.99.3 (heme oxygenase)
 4,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of retinoic acid (RA) (50 micrograms/100 g body wt. per day) on hepatic heme oxygenase activity, delta-aminolevulinate synthase (ALAS) activity and on cytochrome P-450 content were determined in thyroidectomized rats treated with T3 (10 micrograms/100 g body wt. per day) or diluent. RA, when administered for 3 days, failed to influence significantly the activity of either heme oxygenase or ALAS, however, the retinoid depleted hepatic cytochrome P-450 content by 17% (P less than 0.01) and microsomal heme content by 47% (P less than 0.001). T3 administration enhanced heme oxygenase activity by 72% (P less than 0.001) and ALAS activity by 251% (P less than 0.001) above levels in diluent treated controls and depleted cytochrome P-450 levels by 55% (P less than 0.001) and heme levels by 75% (P less than 0.001). When RA and T3 were administered together, the retinoid markedly enhanced the T3 stimulation of heme oxygenase activity; 173% above controls (P less than 0.001), and 61% above T3 alone (P less than 0.001). However, RA failed to influence the effect of T3 on ALAS activity or cytochrome P-450 depletion. The results indicate that RA can influence the levels of hepatic cytochrome P-450 and can modulate the stimulation of heme oxygenase activity by thyroid hormone in vivo.
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PMID:Retinoic acid can enhance the stimulation by thyroid hormone of heme oxygenase activity in the liver of thyroidectomized rats. 165 72

The effects of 3,5,3'-triiodothyronine (T3) on heme oxygenase (EC 1.14.99.3) activity and cytochrome P-450 content in liver were examined in thyroidectomized rats. T3, when administered for 5 days at a dose of 6 micrograms/100 g of body weight, stimulated basal heme oxygenase activity approximately equal to 2-fold compared to diluent-treated animals. The induction of heme oxygenase by cobalt heme also was enhanced approximately equal to 3-fold in T3-treated animals. T3 treatment lowered cytochrome P-450 content by approximately equal to 50% and potentiated the depletion of this heme protein after cobalt heme administration. Reverse T3 had no effect either on cytochrome P-450 content or on heme oxygenase activity in liver. The time course of response to a single dose of T3 (50 micrograms/100 g of body weight) revealed that both basal and cobalt heme-induced heme oxygenase activity peaked at 48 hr and that cytochrome P-450 content declined to approximately equal to 40% of controls at 96 hr. Examination of microsomal proteins by polyacrylamide gel electrophoresis after T3 treatment disclosed that major bands in the Mr approximately equal to 50,000-55,000 region were diminished. The administration of T3 together with SKF-525A, a compound known to complex with the heme prosthetic group of cytochrome P-450, resulted in partial preservation of these proteins. These data indicate that thyroid hormone can regulate heme oxygenase activity and concomitantly can lower cytochrome P-450 content in liver. The hormone also can act in a synergistic fashion to enhance the response of hepatic heme oxygenase to a chemical inducer of the enzyme. Thyroid status thus may be a potentially significant determinant of the rate of heme oxidation in the liver.
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PMID:Thyroid hormone regulation of heme oxidation in the liver. 696 31