The study of the protective effect of mitochondrial uncouplers during acute toxicity of the fungicide difenoconazole in different organs of mice.

Pesticides represent a serious problem for agricultural workers due to their neurotoxic effects. The aim of this study was to evaluate the ability of pharmacological oxidative phosphorylation uncouplers to reduce the effect of the difenoconazole fungicide on mitochondrial DNA (mtDNA) of various organs in mice. Injections of difenoconazole caused cognitive deficits in mice, and the protonophore 2,4-dinitrophenol (2,4-DNP) and Azur I (AzI), a demethylated metabolite of methylene blue (MB), prevented the deterioration of cognitive abilities in mice induced by difenoconazole. Difenoconazole increased the rate of reactive oxygen species (ROS) production, likely through inhibition of complex I of the mitochondrial respiratory chain. After intraperitoneal administration of difenoconazole lungs, testes and midbrain were most sensitive to the accumulation of mtDNA damage. In contrast, the cerebral cortex and hippocampus were not tolerant to the effects of difenoconazole. The protonophore 2,4-DNP reduced the rate of ROS formation and significantly reduced the amount of mtDNA damage caused by difenoconazole in the midbrain, and partially, in the lungs and testes. MB, an alternative electron carrier capable of bypassing inhibited complex I, had no effect on the effect of difenoconazole on mtDNA, while its metabolite AzI, a demethylated metabolite of MB, was able to protect the mtDNA of the midbrain and testes. Thus, mitochondria-targeted therapy is a promising approach to reduce pesticide toxicity for agricultural workers.

The Relationship of p62 Gene Expression with Integrity of Mitochondrial DNA and the Level of Lipid Peroxidation Products in Skeletal Muscles of Rats of Different Ages Exposed to Different Feeding Protocols.

Sequestosome-1 (SQSTM1/p62) is one of the most important multifunctional proteins, which is necessary to maintain mitochondrial stability by eliminating damaged mitochondria through mitophagy. We studied the influence of age and diet on the expression of the p62 gene in the femoral and abdominal muscles of rats, as well as the integrity of some mitochondrial components. In the femoral muscles of 24-month-old rats receiving restricted ration, the expression of the p62 gene increased. We assume that activation of mitophagy contributed to a decrease in the levels of oxidative damage to mitochondrial DNA and LPO intensity in the femoral muscles of 24-month-old rats.

The Effect of Methylene Blue and Its Metabolite-Azure I-on Bioenergetic Parameters of Intact Mouse Brain Mitochondria.

Methylene blue, a phenothiazine dye, that is widely used in medicine and is under clinical trials as an agent for treatment of Alzheimer's disease. One of the factors of the unique therapeutic effect of methylene blue is its redox properties, allowing implementation of alternative electron transport: the dye accepts electrons from reducing equivalents in mitochondria and transfer them to other components of the respiratory chain or molecular oxygen. Azure I, an N-dimethylated metabolite of methylene blue, is potentially a more effective compound than methylene blue, but its ability for alternative electron transport has not been studied yet. We have shown that in contrast to methylene blue, azure I is unable to restore the membrane potential in isolated mouse brain mitochondria, inhibited by rotenone and, therefore, is unable to perform bypass of the respiratory chain complex I. Moreover, addition of azure I does not affect the rate of mitochondrial respiration in contrast to methylene blue, which increases the rate of non-phosphorylation respiration. At the same time, both dyes stimulate an increase in H2O2 production. Thus, only methylene blue is capable of alternative electron transport, while azure I does not produce complex I bypass. This limits its therapeutic application only as a mitochondrial-targeted agent, but does not question its antidepressant effects.

[Effect of methylene blue and its metabolite - azure I - on bioenergetic parameters of intact mice brain mitochondria]. / Vliianie metilenovogo sinego i ego metabolita ­ azura I ­ na bioénergeticheskie parametry izolirovannykh mitokhondrii mozga myshei.

Methylene blue is a phenothiazine dye that is widely used in medicine and clinical trials for the treatment of Alzheimer's disease. One of the factors of the unique therapeutic effect of methylene blue is its redox properties, allowing implementation of alternative electron transport - the dye accepts electrons from reducing equivalents in the mitochondria and transfer it them to other components of the respiratory chain or molecular oxygen. Azure I, an N-dimethylated metabolite of methylene blue, is potentially a more effective compound than methylene blue, but its ability for alternative electron transport has not been studied. We have shown that azure I, unlike methylene blue, is unable to restore the membrane potential in isolated mouse brain mitochondria, inhibited by rotenone and, therefore, is unable to perform bypass of the respiratory chain Complex I. Moreover, the addition of azure I does not affect the rate of mitochondrial respiration in contrast to methylene blue, which increases the rate of non-phosphorylation respiration. At the same time, both dyes stimulate an increase in H2O2 production. As a consequence, only methylene blue is capable of alternative electron transport, while azure I does not produce complex I bypass. This limits its therapeutic application only as a mitochondrial-targeted drug, but not as a substance with a potentially powerful antidepressant effect.

[The effect of L-carnitine depletion induced by long-term therapy of mice with meldonium on brain mitochondrial balance]. / Vliianie istoshcheniia L-karnitina pri dlitel'noi terapii mel'doniem na mitokhondrial'nyi balans v mozge myshei.

Meldonium is a metabolic drug used for treatment of coronary heart disease. The effect of the drug lies in its ability to inhibit synthesis and transport of L-carnitine. At the same time, a long-term deficiency of L-carnitine can theoretically negatively affect the activity of the transcription factor Nrf2, which is extremely important for maintaining mitochondrial balance in cells. We have shown that meldonium therapy for 3 months at a dose of 100 mg/kg in mice causes a decrease in the expression of the Nrf2 gene in the brain. A decrease in the Nrf2 level causes suppression of mitochondrial biogenesis, which is manifested in a decrease in the level of mtDNA and the level of Cox1 expression. However, no negative effect of meldonium on the bioenergetics parameters of mitochondria was found, as evidenced by the maintenance of a stable mitochondrial potential and the level of production of reactive oxygen species. Jne mohth after the end of the meldonium therapy, expression of the genes responsible for mitochondrial biogenesis and mitophagy (p62, Pink1, Tfam) was observed and the expression level of genes responsible for mitochondrial fusion returned to control values. These changes may be associated with the normalization of the level of L-carnitine in brain cells.

[The fenofibrate effect on genotoxicity in brain and liver and on the expression of genes regulating fatty acids metabolism of mice]. / Vliianie fenofibrata na genotoksichnost' v mozge i pecheni i na ékspressiiu genov, reguliruiushchikh metabolizm zhirnykh kislot, u myshei.

Fibrates are well-known agonists of the PPAR family (peroxisome proliferator-activated receptors). This class of drugs is used for the treatment of dyslipidemia and atherosclerosis. Fenofibrate is one of the members of this class of synthetic PPARα receptor ligands. The oral administration of 0.3% fenofibrate caused a decrease in strength due to loss of body weight in laboratory animals when improving behavioural features. Analysis of the mitochondrial DNA of liver cells showed a genotoxic effect of fenofibrate, due to accumulation of reactive oxygen species, which could be attributed to activation of peroxisomal ß-oxidation processes, as well as to the lack of increase in the expression of genes encoding antioxidant defense proteins. Treatment with fenofibrate did not cause brain mtDNA damage. It has been shown that fenofibrate induced mitochondrial ß-oxidation in the brain, as indicated by the increased expression of the Acadm and Cpt1a and Ppargc1a and Ppara. The study found no effect of fenofibrate on the increase of mitochondrial biogenesis in brain and liver cells. Thus, we can conclude that fenofibrate significantly affects lipid metabolism in the liver and brain, but in the liver it is associated with an increase of oxidative stress, resulting in mtDNA oxidative damage. However, fenofibrate-induced increase in the expression of Ppargc1a is not associated with an increase of mitochondrial biogenesis. This is consistent with the recent suggestion that PGC-1α might not be a master regulator of mitochondrial biogenesis.

[The effect of fenofibrate on expression of genes involved in fatty acids beta-oxidation and associated free-radical processes]. / Vliianie fenofibrata na ékspressiiu genov beta-okisleniia zhirnykh kislot i sviazannye s nim svobodnoradikal'nye protsessy.

Fenofibrate is a synthetic ligand for peroxisome proliferator-activated receptors subtype alpha (PPARa); it is used for the treatment of a wide range of metabolic diseases such as hypertriglyceridemia, dyslipidemia, diabetes and various neurodegenerative diseases. We have studied the effect of fenofibrate on b-oxidation of fatty acids and related free-radical processes. The most effective concentration of fenofibrate (0.3%) added to the chow caused a significant decrease of the body weight of mice. The data obtained by quantitative PCR demonstrated increased hepatic gene expression responsible for b-oxidation of fatty acids in peroxisomes and mitochondria. Enhancement of oxidative processes caused a 2-fold increase in the rate of reactive oxygen species (ROS) production, as evidenced by determination of the level of lipid peroxidation (LPO) products in the liver. Mitochondrial antioxidant systems are more sensitive to elevated ROS production, as they respond by increased expression of SOD2 and PRDX3 genes, than cytoplasmic and peroxisomal antioxidant systems, where expression of CAT1, SOD1, PRDX5 genes remained unaltered.