[Dependence of lipid peroxidation changes and antioxidant activity in myocardium under acute and chronic stress from...

In experiments on 122 unbreed white male rats with body weight 250-300 g investigated influence of thyroid status on evoked by chronic stress (CS--immobilization on 3 h during 5 days) and acute stress (AS--once immobilization during 3 h) changes of lipid peroxidation (LP) intensivity and antioxidant activity (AOA) in myocardium. It was shown that chronic stress, which decreases triiodothyronine and thyroxine levels in blood, leads to more market LP activation and lowering of superoxiddismutase activity in myocardium than acute stress, which reducts only T3 concentration. Close correlation between T3 and T4 concentration in blood and LP speed, level of its products, general AOA in myocardium was founded in both stresses. Hypothyrosis (1.2 mg/kg body weight during 14 days intragastrally) leads to more market accumulation of initial lipid peroxidation products and general AOA depression in myocardium under acute and, especially, chronic stress. Like to physiological doses of thyroxine (from 5.0 to 8.0 mkg/kg body weight during 28 days same way) prevent LP activation and limit AOA decreasing in myocardium under both stresses.