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Hepatic glutathione biosynthetic capacity in hyperthyroid rats
1Departamento de Bioquímica, Facultad de Medicina, Universidad de Chile, Santiago-7, Chile.
Toxicology Letters
|December 16, 1996
Summary
Hyperthyroidism depletes liver glutathione (GSH) by increasing its utilization more than synthesis. This leads to lower GSH levels in hyperthyroid rats, impacting liver function.
Area of Science:
- Biochemistry
- Endocrinology
- Hepatology
Background:
- Glutathione (GSH) is a critical tripeptide antioxidant in the liver.
- Hyperthyroidism is associated with altered metabolic states and potential oxidative stress.
Purpose of the Study:
- To investigate the effect of hyperthyroidism on hepatic glutathione (GSH) synthesis.
- To elucidate the mechanism behind GSH depletion in hyperthyroid states.
Main Methods:
- Administered 3,3',5-tri-iodothyronine (T3) to rats to induce hyperthyroidism.
- Assessed hepatic GSH biosynthetic capacity using simultaneous gamma-glutamylcysteinyl synthase and GSH synthase assays.
- Utilized L-buthionine sulfoximine to inhibit GSH synthesis.
Main Results:
- T3 treatment caused a significant 56% depletion of liver GSH.
- The rate of GSH synthesis increased in hyperthyroid rats but was insufficient to maintain normal levels.
- Hepatic GSH turnover rate was 3.2-fold higher in hyperthyroid rats.
Conclusions:
- Hyperthyroidism enhances hepatic GSH utilization beyond the capacity of increased GSH synthesis.
- This imbalance results in a low steady-state concentration of GSH in the liver of hyperthyroid animals.
- The findings suggest impaired antioxidant defense in the liver during hyperthyroidism.