Heat exposure and hypothyroid conditions decrease hydrogen peroxide generation in liver mitochondria

Abstract

Exposure of rats to heat (39 +/- 1 degree C) decreased H2O2 generation in mitochondria of the liver, but not of the kidney or the heart. The effect was obtained with three substrates, succinate, glycerol 1-phosphate and choline, with a decrease to 50% in the first 2-3 days of exposure, and a further decrease on longer exposure. The dehydrogenase activity with only glycerol 1-phosphate decreased, which is indicative of the hypothyroid condition, whereas choline dehydrogenase activity remained unchanged and that of succinate dehydrogenase decreased on long exposure. The serum concentration of thyroxine decreased in heat-exposed rats. Thyroxine treatment of rats increased H2O2 generation. Hypothyroid conditions obtained by treatment with propylthiouracil or thyroidectomy caused a decrease in H2O2 generation and changes in dehydrogenase activities similar to those with heat exposure. Treatment of heat-exposed or thyroidectomized rats with thyroxine stimulated H2O2 generation by a mechanism apparently involving fresh protein synthesis. The results indicate that H2O2 generation in mitochondria of heat-exposed animals is determined by thyroid status.

Oxidative Stress and Antioxidant Status in Hypo- and Hyperthyroidism

“…GSH: GSSG in tissue is now considered one of the important markers of oxidative stress. The decrease in its ratio and the restoration to its normal value by T3 administration confirms the critical role of thyroid hormone in regulating mitochondrial oxidative stress [13].…”

“…In hypothyroidism, a decrease in free radical production is expected because of the metabolic supression brought about by the decrease in thyroid hormone levels [12,13,14].…”

Flow‐cytometric analysis of reactive oxygen species in peripheral blood mononuclear cells of patients with thyroid dysfunction

“…Studies conducted in rat models have also demonstrated an increase in free radical production and lipid peroxide levels during hypermetabolic state (4,7,8), while the hypometabolic state induced by hypothyroidism is associated with a decrease in free radical production (9) and lipid peroxidation products (10). However, alterations in ROS levels have not been demonstrated in the cells or tissues of patients having thyroid dysfunction.…”

Gestational Prooxidant-Antioxidant Imbalance may be at Higher Risk for Postpartum Thyroid Disease

“…On the other hand, hypothyroidism is associated with cellular ionic imbalance, augmented oxidative stress, and decreased GSH and glutathione-Stransferase (GST) [2,5,6,[39][40][41]. Also, a reduction in the levels of free radical is predictable on account of the metabolic inhibition by the hypothyroid state [42][43][44]. This disturbance has deleterious effect on the health of the newborns and adulthood [5-10].…”