Methylene blue elicits non-genotoxic H₂O₂ production and protects brain mitochondria from rotenone toxicity

Abstract

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.

High Doses of Pesticides Induce mtDNA Damage in Intact Mitochondria of Potato In Vitro and Do Not Impact on mtDNA Integrity of Mitochondria of Shoots and Tubers under In Vivo Exposure

“…When evaluating the results of an in vitro experiment, it was found that the damage to mtDNA obtained after treatment with metribuzin and imidacloprid at a concentration of 200 µM is equivalent to the damage induced by treatment with H 2 O 2 at a concentration of 500 µM (Figure 2A, Table 1). We have previously shown similar results when treating mouse brain mitochondria with 500 µM H 2 O 2 and 1 µM rotenone pesticide, where rotenone caused even slightly more damage than H 2 O 2 [52]. It is believed that mtDNA damage is mainly initiated by ROS [53].…”

Effect of long-term methylene blue treatment on the composition of mouse gut microbiome and its relationship with the cognitive abilities of mice

“…The studies in rats have shown that the optimal concentration for the injection is 1 to 4 mg/kg [24,25]. Single injections of 50-100 mg/kg MB suppressed the running wheel behavior [26] but did not cause a genotoxic effect [27]. When MB was taken orally with drinking water, a positive effect was observed in the MB concentration range from 15 to 40 mg/kg/ day [28][29][30].…”

Hereditary Spastic Paraplegia and Future Therapeutic Directions: Beneficial Effects of Small Compounds Acting on Cellular Stress

“…MB is a nootropic agent that inhibits acetylcholinesterase activity and at large doses also monoamine oxidase, thus increasing the levels of catecholamines and acetylcholine ( Pfaffendorf et al, 1997 ; Ramsay et al, 2007 ; Delport et al, 2017 ). Moreover, MB has an important role in mitochondrial energy through the modulation of respiration; it accepts electrons from NADPH (becoming leukomethylene blue MBH) and transfers them to cytochrome c. Therefore, MB is used to enhance mitochondrial function, acting as an alternative electron carrier in the electron transport chain in the mitochondria ( Wen et al, 2011 ; Gureev et al, 2019 ). MB also stimulates glucose metabolism, increasing glucose uptake and ATP production, providing more cellular energy for a better overall brain function including cognition, mood, and memory ( Atamna et al, 2008 ; Rojas et al, 2012 ; Alda et al, 2017 ; Sonntag et al, 2017 ).…”