Chemiluminescent and Respiratory Responses Related to Thyroid Hormone-Induced Liver Oxidative Stress

Abstract

Chemiluminescent and respiratory responses were studied in the liver of rats treated with 0.1 mg of triiodothyronine (T3)/kg for 1 to 7 days. Hyperthyroidism resulted in significant increments in the spontaneous chemiluminescence of the in situ liver in animals exhibiting a calorigenic response. Microsomal NADPH-dependent oxygen uptake was enhanced by T3 treatment for 2 days, an effect that was completely abolished by the antioxidant cyanidanol. A similar microsomal antioxidant-sensitive respiratory component was observed in this situation after the addition of t-butyl hydroperoxide (t-BHP). However, basal rates of microsomal oxygen uptake and light emission in liver homogenates and microsomes were decreased by t-BHP, probably related to thyroid hormone-induced diminution in the content of cytochrome P-450 (Fernández et al.) In addition, liver superoxide dismutase and catalase activities as well as the total content of glutathione were depressed by T3. These results indicate that the calorigenic response in the hyperthyroid state is accompanied by the development of an hepatic oxidative stress characterized by enhanced spontaneous chemiluminescence, enhanced NADPH-dependent microsomal respiration and a decreased antioxidant cellular activity.

Inhibition of lipid peroxidation and iron (II)-dependent DNA damage by extracts of Pothomorphe peltata (L.) Miq

“…Although all the extracts tested showed the ability to reduce lipid peroxidation by this method (Table 2), no significant differences were observed between them. Hydroperoxide-initiated chemiluminescence was more sensitive than TBARS production to determine changes in lipid peroxidation, as reported previously (24)(25)(26). Similarly, catechin was highly effective in inhibiting the hydroper- Table 1 -Antioxidant activity in extracts of P. peltata using the hydroperoxide-initiated chemiluminescence assay.…”

Oxidative Stress and Antioxidant Status in Hypo- and Hyperthyroidism

“…Total SOD was found to decrease in liver [180] and increase in heart from young [120,157] but not from old [120] hyperthyroid rats.…”

“…In some studies, it has been reported that SOD activity was significantly increased [12,179,181]. On the contrary, several authors reported that SOD activity were reduced in patients with hyperthyroidism [180,182].…”

“…This not only confirms the main role of the thyroid hormones in regulating the oxidative stress in target cells, but also is in agreement with previous data. GSH depletion, a major hepatic alteration induced by hyperthyroidism in experimental animals [199] and [180] and man [217], is determined by both loss of tripepetide into the blood and higher intracellular catabolism, despite the enhancement in the rate of GSH synthesis and in the GSH turnover rate triggered in the liver [199,218]. Enhanced production of free radicals and the increase of antioxidant enzymes activities have been suggested as possible mechanisms to explain hyperthyroid-induced oxidative damage [219].…”

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

“…Hyperthyroidism has been associated with free radicalmediated damage to muscular tissues (7) and liver (20). Oxidative tissue injury is a secondary phenomenon to increased production of active oxygen species.…”