Glutathione correlates with lipid peroxidation in liver mitochondria of triiodothyronine‐injected hypophysectomized rats

The temporal relationship of changes in state 3 respiration, lipid peroxidation, and glutathione (GSH) content was investigated in liver mitochondria of hypophysectomized rats after an injection of 3,3',5‐triiodo‐ l ‐thyronine (T 3 ). Lipid peroxidation induced by ADP/Fe 3+ /NADPH was determined by the amount of malondialdehyde formed. Hypophysectomy decreased respiration and lipid peroxidation (from 19.88 ± 3.04 to 14.19 ± 1.14 nmol malondialdehyde · mg protein −1 · 10 min −1 ) but increased GSH content (from 7.06 ± 2.08 to 12.46 ± 3.58 nmol/mg protein). Daily injections of a low dose (5 μg/100 g) of T 3 for 7 days restored the parameters. Time course (up to 96 h) of these changes was followed after one injection of a moderate (100 μg/100 g) and high (1000 μg/100 g) dose of the hormone. Respiration showed a significant increase at 24 h and declined slightly at 96 h. There was a slow loss of respiratory control ratio after 24 h. Lipid peroxidation remained unchanged at 24 h and showed a gradual increase, becoming significantly higher at 72‐96 h depending on the hormone dosage. Changes in GSH content followed a time course similar to that of lipid peroxidation except that it showed a decrease instead of an increase. There was a high degree of inverse linear correlation between lipid peroxidation and GSH (correlation coefficient = 0.95). Because GSH is required for detoxification of hydroperoxides generated by the respiratory chain, it is suggested that lipid peroxidation may play a major role in the modulation of intramitochondrial GSH.— M addaiah , V. T. Glutathione correlates with lipid peroxidation in liver mitochondria of triiodothyronine‐injected hypophysectomized rats. FASEB J. 4: 1513‐1518; 1990.