Recovery from silver-nanoparticle-exposure-induced lung inflammation and lung function changes in Sprague Dawley rats

Abstract

In a previous study, the lung function, as indicated by the tidal volume, minute volume, and peak inspiration flow, decreased during 90 days of exposure to silver nanoparticles and was accompanied by inflammatory lesions in the lung morphology. Therefore, this study investigated the recovery from such lung function changes in rats following the cessation of 12 weeks of nanoparticle exposure. Male and female rats were exposed to silver nanoparticles (14–15 nm diameter) at concentrations of 0.66 × 10⁶ particles/cm³ (49 μg/m³, low dose), 1.41 × 10⁶ particles/cm³ (117 μg/m³, middle dose), and 3.24 × 10⁶ particles/cm³ (381 μg/m³, high dose) for 6 h/day in an inhalation chamber for 12 weeks. The rats were then allowed to recover. The lung function was measured every week during the exposure period and after the cessation of exposure, plus animals were sacrificed after the 12-week exposure period, and 4 weeks and 12 weeks after the exposure cessation. An exposure-related lung function decrease was measured in the male rats after the 12-week exposure period and 12 weeks after the exposure cessation. In contrast, the female rats did not show a consistent lung function decrease either during the exposure period or following the exposure cessation. The histopathology showed a gradual recovery from the lung inflammation in the female rats, whereas the male rats in the high-dose group exhibited persistent inflammation throughout the 12-week recovery period. Therefore, the present results suggest a potential persistence of lung function changes and inflammation induced by silver nanoparticle exposure above the no observed adverse effect level.

Keywords::

• Silver nanoparticle
• lung function
• recovery
• inhalation exposure
• subchronic

Acknowledgements:

This work was supported by the Korea Research Council of Fundamental Science and Technology (KRCF) through the project “Development of Characterization Techniques for Nano-material Safety.”

Declaration of interest:

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.