Related Experiment Video
Updated: Aug 17, 2026
Quantification of three DNA Lesions by Mass Spectrometry and Assessment of Their Levels in Tissues of Mice Exposed to Ambient Fine Particulate Matter
Published on: May 29, 2019
Susceptibility of DNA to oxidative stressors in young and aging mice
Norma E López-Diazguerrero1, Armando Luna-López, María C Gutiérrez-Ruiz
1Departamento de Ciencias de la Salud, División de Ciencias Biológicas y de la Salud, UAM-Iztapalapa, A.P. 55-535, México, D.F. 09340, México.
Abstract:
The changes that accompany aging may be a result of oxidative damage to DNA that accumulates as a result of aging and age-related illnesses. Furthermore, a higher susceptibility is thought to be more common among elderly than young individuals. In the present study, we examined the severity of DNA damage caused by carbon tetrachloride (CCl4) and H2O2 in cells from young (2 month old) and older (14 month old) mice using both in vivo and in vitro exposures. CCl(4) is known to generate radical oxidative species (ROS) throughout its biotransformation in the liver. Therefore, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxdGuo) was quantified in liver DNA obtained from young and older mice treated with CCl4. In addition, DNA single-strand breaks were measured by the Comet assay in primary lung fibroblasts cultured from young and older mice and treated in vitro with H2O2. Intracellular ROS production and mitochondrial enzyme activity were determined in parallel. 8-oxodGuo levels were significantly higher in older mouse liver DNA than younger, and increased significantly with CCl4 treatment. When the basal DNA damage was subtracted, the net damage was almost equal for both. In addition, untreated cells cultured from older mice had significantly greater levels of strand breaks than cells derived from young mice. H2O2 increased the level of damage in both cell cultures. Our findings indicate that the DNA damage observed in older animals probably results from the accumulation of endogenous damage with age, perhaps due to insufficient repair, which enhances the injury caused by exposure to the toxic agents.
Insights
Aging increases susceptibility to DNA damage from oxidative stress. Older mice showed higher basal DNA damage, with similar increases to younger mice after toxic exposure, suggesting age-related repair deficits.
Area of Science:
- Gerontology
- Molecular Biology
- Toxicology
Background:
- Aging is associated with increased oxidative stress and DNA damage.
- Elderly individuals may be more susceptible to environmental toxins.
- Accumulated DNA damage is a potential driver of aging and age-related diseases.
Purpose of the Study:
- To investigate age-related differences in DNA damage response.
- To compare DNA damage severity in young versus aged mice exposed to carbon tetrachloride (CCl4) and hydrogen peroxide (H2O2).
Main Methods:
- In vivo and in vitro exposure of young (2-month-old) and old (14-month-old) mice to CCl4 and H2O2.
- Quantification of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) in liver DNA.
- Measurement of DNA single-strand breaks using the Comet assay in lung fibroblasts.
- Assessment of intracellular reactive oxygen species (ROS) production and mitochondrial enzyme activity.
Main Results:
- Older mice exhibited significantly higher basal levels of 8-oxodGuo in liver DNA compared to younger mice.
- CCl4 treatment significantly increased 8-oxodGuo levels in both age groups, with similar net increases after subtracting basal damage.
- Cultured fibroblasts from older mice showed significantly more DNA strand breaks than those from younger mice, even without toxicant exposure.
- H2O2 exposure increased DNA damage in cells from both young and old mice.
Conclusions:
- The heightened DNA damage in older animals likely stems from accumulated endogenous damage over time.
- Age-related declines in DNA repair mechanisms may contribute to increased susceptibility to toxic agents.
- Oxidative stress and DNA damage are critical factors in the aging process.
