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Age-dependent pulmonary response of rats to ozone exposure
Insights
Younger rats (7-12 days) showed decreased lung function and increased mortality from ozone (O3) exposure, indicating higher susceptibility. Older rats (60-90 days) exhibited a greater O3-induced biochemical response, suggesting increased responsiveness to lung injury.
Area of Science:
- Environmental Toxicology
- Pulmonary Physiology
- Developmental Biology
Background:
- Ozone (O3) is a significant air pollutant with known respiratory effects.
- The impact of O3 exposure on lung development and function across different age groups is not fully understood.
Purpose of the Study:
- To investigate the influence of age on the effects of ozone exposure in Sprague-Dawley rats.
- To assess age-related differences in lung biochemical responses and susceptibility to O3-induced stress.
Main Methods:
- Eight age groups of rats (7 days to 90 days old) were exposed to 0.8 ppm O3 for 3 days.
- Lung weight, total lung protein and DNA content, and marker enzyme activities were measured.
- Biochemical parameters were analyzed relative to age-matched controls.
Main Results:
- A biphasic O3 effect was observed across age groups.
- Neonatal rats (7-12 days) showed decreased lung biochemical parameters and increased mortality, indicating high susceptibility.
- Infant (24-30 days) and adult (60-90 days) rats exhibited increased lung biochemical parameters, with older rats showing a greater response, suggesting higher responsiveness to O3 injury and repair.
Conclusions:
- Age significantly influences the lung's response to ozone exposure.
- Neonatal rats are more susceptible to O3 stress, while adult rats are more responsive to O3-induced lung injury and repair processes.
- These findings highlight critical age-dependent vulnerabilities and responses to air pollution.
Abstract:
The influence of age on O3 effects in the lung was studied in 8 groups of Sprague-Dawley rats: 7, 12, and 18 d of age (neonatal); 24, 30, and 45 d of age (infant); and 60 and 90 d of age (adult). Lung weight, total lung protein and DNA contents, and a series of marker enzyme activities in lung tissue were determined. After exposure of rats from each group to 0.8 ppm (1568 microgram/m3) O3 continuously for 3 d, a biphasic effect was noted. The biochemical parameters, expressed per lung, in O3-exposed rats relative to their corresponding controls decreased in the 7- and 12-d-old groups, increased or remained unchanged in the 18-d-old group, and increased in the 24- to 90-d-old groups. However, the increases were much greater for 60- to 90-d-old rats than for 24- to 30-d-old rats. The increase in lung biochemical parameters is thought to occur in response to lung injury and subsequent repair processes, and greater increases in the lungs of older rats suggest that they are more responsive to O3 exposure than younger rats. The decrease in lung biochemical parameters and increased mortality in 7- and 24-d-old neonatal rats suggest that they are more susceptible to O3 stress than infant and adult rats.