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Inhibition of mitochondrial DNA synthesis by aflatoxin B1 and dimethylnitrosamine
Abstract:
The acute and subchronic effects of aflatoxin B1 and dimethylnitrosamine (DMN) on in vitro incorporation of thymidine-3H into DNA (mt-DNA) from mouse liver mitochondria were studied after single injection or after one month or three months of weekly injection. Both carcinogens induced 50% decreases in mt-DNA synthesis acutely, with a 50% decrease in synthesis of high molecular weight mt-DNA. Subchronic administration of aflatoxin B1 inhibited mt-DNA synthesis by 54% with elution profiles similar to the controls. DMN showed only a 29% inhibition of mt-DNA synthesis at one month increasing to 55% at three months.
Insights
Both aflatoxin B1 and dimethylnitrosamine (DMN) significantly reduced mitochondrial DNA (mt-DNA) synthesis in mice. DMN
Area of Science:
- Toxicology
- Molecular Biology
- Carcinogenesis
Background:
- Aflatoxin B1 and dimethylnitrosamine (DMN) are known carcinogens.
- Mitochondrial DNA (mt-DNA) plays a crucial role in cellular energy production and is susceptible to damage.
- Understanding the impact of toxins on mt-DNA synthesis is vital for assessing carcinogenic potential.
Purpose of the Study:
- To investigate the acute and subchronic effects of aflatoxin B1 and DMN on mouse liver mitochondrial DNA (mt-DNA) synthesis.
- To determine the impact of these carcinogens on high molecular weight mt-DNA synthesis.
- To compare the dose-dependent effects of aflatoxin B1 and DMN on mt-DNA synthesis over time.
Main Methods:
- Mice were administered single or weekly injections of aflatoxin B1 or DMN for one or three months.
- In vitro incorporation of thymidine-3H into mt-DNA from mouse liver mitochondria was measured.
- Elution profiles of mt-DNA synthesis were analyzed.
Main Results:
- Both aflatoxin B1 and DMN caused a 50% acute decrease in mt-DNA synthesis and high molecular weight mt-DNA synthesis.
- Subchronic aflatoxin B1 administration resulted in a 54% inhibition of mt-DNA synthesis.
- Subchronic DMN administration showed a 29% inhibition at one month, increasing to 55% at three months.
Conclusions:
- Aflatoxin B1 and DMN are potent inhibitors of mitochondrial DNA synthesis.
- DMN exhibits a time-dependent increase in its inhibitory effect on mt-DNA synthesis.
- These findings highlight the potential of these carcinogens to disrupt mitochondrial function.