O.A. Safonova, T.N. Popova, L. Saidi

The investigation of free-radical oxidation (FO) processes intensity and activities of enzymes-antioxidants - superoxide dismutase (SOD) and catalase, in rats tissues at citrate introduction under experimental thyrotoxicosis (ET) was carried out. Because of oxidative stress development under thyroid hormones (TG) high concentrations in organism, investigation of opportunity of antioxidants application for increase of this disease therapy effectiveness is urgent. Antioxidant properties may be displayed by endogenous metabolite - citrate, due to chelating of prooxidants: Fe2+ ions, as well as of Ca2+ ions. ET at males of white rats was induced by intraperitoneal triiodothyronine introduction in 1 mg/kg of weight dose three times in 6 days. Citrate was introduced in 50 mg/kg dose 3 times. FO processes level and the general antioxidant activity was estimated by biochemiluminescence (BCL) method. The activity of enzymes was registered spectrophotometrically. The decrease of BCL parameters, enlarging under ET, was estimated in rats tissues at citrate introduction on the pathology development background. So, BCL lightsum (S) in the liver reduced in 1.2 times, in heart and blood serum - in 1.4 times; BCL maximum flash intensity (Imax) ? in liver in 1.5 times, in heart and blood serum in 1.3 times concerning the data under pathology. These BCL parameters changes, reflecting FO level, to the side of control meanings testify about these processes inhibition in animals tissues after citrate introduction. Change of BCL kinetic curve fall angle tangent (tgα2), reflecting general antioxidant system activity, in tissue of liver, heart and blood serum to the side of control was observed at citrate introduction to the animals with ET: its decrease in 1.1, 1.2 and 1.9 times accordingly concerning level at the pathology was revealed. In this time SOD and catalase specific activities, increasing under thyrotoxicosis development, also decreased. So, SOD activity in liver reduced in 1.3 times, in heart and blood serum - in 1.2 times; catalase activity fell in liver on 10 %, in heart on 16 %, in blood serum on 13 % compared with that under ET. It may be assumed, that FO level reduces in connection with citrate antioxidant properties display, that apparently is accompanied by decrease of load on the antioxidants, in particular, on SOD and catalase compared with the pathology. Binding of participating in free-radical processes development Fe2+ and Ca2+ ions by carboxyl groups of citrate may lie in the basis of this substance antioxidant action. Thus, citrate is apparent to promote metabolic processes normalization, in particular, free-radical homeostasis, in organism in conditions of TG in high concentrations damaging action.