Tag Archives: SH-groups
Free radical processes in the liver mitochondria of rats exposed to diethyl phthalate
O. V. Ketsa*, A. P. Husliakova, M. M. Marchenko
Yuriy Fedkovych Chernivtsi National University, Chernivtsi, Ukraine;
*e-mail: o.ketsa@chnu.edu.ua
Received: 11 October 2023; Revised: 28 November 2023;
Accepted: 01 February 2024; Available on-line: 26 February 2024
Diethyl phthalate (DEF) is a synthetic chemical widely used as plasticizer and additive in personal care and pharmaceutical products. Low-dose exposure to this xenobiotic over a long period contributes to its intake into the human body in a high doses. To date, studies of DEF influence on free radical processes in liver cells, in which it is not only metabolized but can also have a prooxidant effect, remain limited. The aim of our research was to determine ROS formation, the intensity of oxidative modification of proteins (OMP) and proteolytic activity in the mitochondrial fraction of liver tissue of rats exposed to diethyl phtalate. The experimental white outbred rats were divided into three groups: I – intact animals (control), II and III – rats administered DEF orally for three weeks at a doses that reflect the dose levels received by humans, namely 2.5 and 5.4 mg/kg b.w. respectively. The animals were euthanized on the 14th and 21st day after xenobiotic administration. The mitochondrial fraction from the rat liver was isolated and the level of superoxide and hydroxyl radicals, protein carbonyl derivatives, SH-groups and Schiff bases was determined. Proteolytic activity was assessed in the test of hemoglobin cleavage. It was shown that administration of DEF in a dose of 2.5 mg/kg initiated ROS generation and OMP intensification in the rat liver mitochondria only with prolonged administration for 21 days, whereas its administration in a dose of 5.4 mg/kg led to intensification of these processes already on day 14th followed by further amplification on day 21st. The activity of proteolytic enzymes in the mitochondrial fraction was found to be depended on the degree of DEF–induced OMP and was increased with minor OMP intensification but decreased with significant intensification of proteins free radical oxidation.
Proteins oxidative modification and antioxidant enzymes activity in the liver mitochondria of rats under laser irradiation and administration of ω-3 polyunsaturated fatty acids
O. V. Ketsa*, M. O. Zelinska, M. M. Marchenko
Fedkovich Chernovtsy National University, Chernovtsy, Ukraine;
*e-mail: o.ketsa@chnu.edu.ua
Received: 12 August 2021; Accepted: 21 January 2022
The effect of laser irradiation of rats combined with omega-3 polyunsaturated fatty acids (ω-3 PUFA) administration on the proteins oxidative modification and superoxide dismutase and catalase activity in the mitochondrial fraction of the liver was investigated. Animals were irradiated with a 650 nm laser diode in the abdomen daily for 4 min at the distance of 10 cm from the skin surface. ω-3 PUFA were administered per os at a daily dose of 120 mg/kg of the body weight. Fatty acids in the fish oil were identified by gas chromatography. Animals were divided into five groups (12 animals in each group): I – intact rats (control); II – rats exposed to the daily laser irradiation for 7 or 14 days ; III – rats that received ω-3 PUFA two hours after irradiation; IV – rats that received ω-3 PUFA two hours before irradiation; V – rats that received ω-3 PUFA for 7 days before irradiation. The mitochondrial fraction of rat liver was obtained by differential centrifugation. The increase in the content of protein carbonyl derivatives and a decrease of protein thiol groups in the liver mitochondrial fraction were detected after seven-day laser irradiation of rats. As the duration of irradiation increases, superoxide dismutase and catalase activity was decreased, indicating a depletion of mitochondrial antioxidant reserves. No antioxidant effect was observed when ω-3 PUFA were administrated after laser irradiation and a slight antioxidant effect was shown when ω-3 PUFA were administrated two hours before irradiation. Preliminary seven-day administration ω-3 PUFA before laser irradiation was the most effective, as it reduced the level of protein carbonyl derivatives and O2•--generation, increased proteins SH-groups content and antioxidant enzymes activity.
The effect of nitric oxide on synaptic vesicle proton gradient and mitochondrial potential of brain nerve terminals
A. S. Tarasenko
Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: tas@biochem.kiev.ua
The effect of nitric oxide on synaptic vesicle proton gradient and membrane potential of rat brain nerve terminals was studied. It has been shown that nitric oxide in the form of S-nitrosothiols at nanomolar concentrations had no effect on the studied parameters, but caused a rapid dissipation of synaptic vesicle proton gradient and depolarization of mitochondrial membrane in the presence of a SH-reducing compound such as dithiothreitol. Both processes were reversible and the rate of H+-gradient restoration depended on the redox potential of nerve terminals, namely the molar ratio of reductant/oxidant. This facts, as well as insensitivity of the studied processes to the inhibitor of NO-sensitive guanylate cyclase such as ODQ, allow suggesting that post-translational modification of thiol residues of the mitochondrial and synaptic vesicle proteins underlies the effect of nitric oxide on the key functional parameters of presynaptic nerve terminals.