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Functional changes in rat liver mitochondria on administration of 2-methyl-4-dimethylaminoazobenzene
Abstract:
Administration of 2-methyl-4-dimethylaminobenzene in the diet (0.1%, w/w) for 85-90 days doubled the content of mitochondria in the livers of rats. The azodye was covalently bound to liver proteins, and about 15% of the amount found in liver was associated with the mitochondrial fraction. Mitochondria isolated from the livers of azodye-fed animals showed drastically lowered ability to oxidize NAD+-linked substrates. The inhibited electron-transfer step was the reduction of ubiquinone. The organelles showed a large increase in succinate oxidase activity. The activity of cytochrome oxidase and the content of cytochrome aa3 were substantially higher in these organelles. Azodye-fed animals showed depressed serum cholesterol concentrations. The content of ubiquinone in liver also registered a small increase.
Insights
Dietary administration of an azodye (2-methyl-4-dimethylaminobenzene) significantly increased liver mitochondria content and altered their function in rats. This study investigated the effects on mitochondrial respiration and key enzyme activities.
Area of Science:
- Biochemistry
- Toxicology
- Cell Biology
Background:
- Mitochondria are crucial for cellular energy production.
- Azodyes are synthetic chemicals with potential toxicological impacts.
- Understanding chemical effects on liver mitochondria is vital for assessing toxicity.
Purpose of the Study:
- To investigate the impact of dietary 2-methyl-4-dimethylaminobenzene on rat liver mitochondria.
- To determine the effects on mitochondrial content, protein binding, and respiratory function.
- To assess changes in specific enzyme activities and biochemical markers.
Main Methods:
- Rats were fed a diet containing 0.1% azodye for 85-90 days.
- Liver mitochondria were isolated and analyzed for content and protein binding.
- Mitochondrial respiratory function, including NAD+-linked substrate oxidation and succinate oxidase activity, was measured.
- Activities of cytochrome oxidase and levels of cytochrome aa3 were quantified.
- Serum cholesterol and liver ubiquinone levels were determined.
Main Results:
- Dietary azodye administration doubled liver mitochondria content.
- Azodye was covalently bound to liver proteins, with 15% associated with mitochondria.
- Mitochondria from exposed rats showed reduced NAD+-linked substrate oxidation, with inhibited ubiquinone reduction.
- Succinate oxidase, cytochrome oxidase activities, and cytochrome aa3 content were significantly increased.
- Serum cholesterol concentrations decreased, and liver ubiquinone content slightly increased.
Conclusions:
- Dietary 2-methyl-4-dimethylaminobenzene alters liver mitochondria biogenesis and function in rats.
- The azodye disrupts specific mitochondrial electron transport chain steps, particularly ubiquinone reduction.
- Increased succinate oxidase and cytochrome oxidase activities suggest adaptive responses or toxicity.
- Observed changes in cholesterol and ubiquinone warrant further investigation into metabolic pathways.