Acute CCl4-induced intoxication reduces complex I, but not complex II-based mitochondrial bioenergetics – protective role of succinate

The main therapeutic strategy for the treatment of patients with toxic liver failure is the elimination of the toxic agent in combination with the targeted mitigation of pathological processes that have been initiated due to the toxicant. In the current research we evaluated the strategy of metabolic supplementation to improve mitochondrial bioenergetics during acute liver intoxication. In our study, we have shown that acute CCl4-induced intoxication negatively affects Complex I (in the presence of glutamate-malate as energy substrates) based respiration, generation of mitochondrial membrane potential (ΔΨm), mitochondrial NAD(P)H pool and NADH redox index, mitochondrial calcium retention capacity (CRC) and structure and functions of the liver. Boosting of mitochondrial bioenergetics through the complex II, using succinate as metabolic substrate in vitro, significantly improved mitochondrial respiration and generation of ΔΨm, but not mitochondrial CRC. Co-application of rotenone along with succinate, to prevent possible reverse electron flow, didn’t show significant differences compared to the effects of succinate alone. Treatment of animals with acute liver failure, using a metabolic supplement containing succinate, inosine, methionine and nicotinamide improved Complex I based respiration, generation of ΔΨm, mitochondrial NAD(P)H pool and NADH redox index, mitochondrial CRC and slightly decreased the level of oxidative stress. These changes resulted in averting destructive and dystrophic changes in the structure of rat liver tissue caused by CCl4 intoxication, concomitantly enhancing hepatic functionality. Thus, we propose that metabolic supplementation targeting complex II could serve as a potential adjunctive therapy in the management of acute liver intoxication.