Methylene blue (MB) is a promising compound with a broad range of neuroprotective activity. One of therapeutic effects is the activation of mitochondrial biogenesis via Nrf2/ARE signaling cascade. Probably, mild oxidative stress caused by MB-depended H 2 O 2 production is a trigger for activation of this signaling cascade. So mechanistically, MB can be regarded as prooxidant. We investigated the dose-dependent H 2 O 2 production in intact brain mitochondria and showed the increase in the H 2 O 2 production after adding as little as 50 nM MB. We have not found genotoxic effect of therapeutic concentration of MB to mitochondrial genome. 100 μM MB selectively damaged fragments of mitochondrial DNA, which correlated with the number of purine-T-G-purine (RTGR)-sequences in studied fragments. Furthermore, 20 μM MB combined with the red light caused the formation of singlet oxygen, which strongly damaged mitochondrial DNA in all studied fragments. We did not observe mitochondrial DNA lesions in brain after single intraperitoneal injection of MB in the concentration of 50 mg/kg. Furthermore, we showed the neuroprotective properties of MB pretreatments after rotenone injection. Therefore, we suggest that MB-induced mild oxidative stress does not have genotoxic effect on mitochondrial DNA.

In this research, we compared the cognitive parameters of 2-, 7-, and 15-month-old mice, changes in mitochondrial DNA (mtDNA) integrity and expression of genes involved in the nuclear erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE) signaling pathway. We showed an age-related decrease in the Nfe2l2 expression in the cerebral cortex, not in the hippocampus. At the same time, we find an increase in the mtDNA copy number in the cerebral cortex, despite the lack of an increase in gene expression, which is involved in the mitochondrial biogenesis regulation. We suppose that increase in mtDNA content is associated with mitophagy downregulation. We supposed that mitophagy downregulation may be associated with an age-related increase in the mtDNA damage. In the hippocampus, we found a decrease in the Bdnf expression, which is involved in the pathways, which play an essential role in regulating long-term memory formation. We showed a deficit of working and reference memory in 15-month-old-mice in the water Morris maze, and a decrease in the exploratory behavior in the open field test. Cognitive impairments in 15-month-old mice correlated with a decrease in Bdnf expression in the hippocampus, Nfe2l2 expression, and an increase in the number of mtDNA damage in the cerebral cortex. Thus, these signaling pathways may be perspective targets for pharmacological intervention to maintain mitochondrial quality control, neuronal plasticity, and prevent the development of age-related cognitive impairment.

No abstract

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 β-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 β-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.

В работе рассматривается метод сбора конденсата выдыхаемого воздуха (КВВ) из выдыхаемой воздушной смеси с учетом сорбционного взаимодействия с пластиком пробирок типа Фалькон.Показано, что ключевым фактором, повышающим эффективность сбора перекиси водорода, являетсяохлаждение пробирки для сбора образцов. По-видимому, это способствовало снижению сорбционного воздействия H2O2 с полипропиленовой поверхностью пластика и соответственно приводило к снижению скорости его распада до воды. В результате работы нами был модифицирован метод измерения концентрации H2O2 в КВВ с использованием реагента Amplex® Ultra Red. Применяя данный метод, установлено, что у пациентов с раком легкого уровень H2O2 в КВВ 9 раз выше, чем у здоровых людей. Полученные данные свидетельствуют о том, что концентрация H2O2 в КВВ может являться потенциальным маркером для ранней диагностики рака легкого