A STUDY OF OXIDATIVE STRESS AND PULMONARY DAMAGE AFTER SILICA INSTILLATION IN RATS AND THE EFFECT OF CURCUMIN ADMINISTRATION

Background: The authors' aim was to study the dynamics of oxidative stress in experimental exposure to silica dust, to evaluate the histopathological findings in the phase preceding the formation of fibrous/fibrohyaline pulmonary nodules, and to assess the effects of curcumin administration. Material and Methods: The research was performed on 48 male Wistar rats with an average weight of 320 g. Overall, 38 rats were instilled with a single dose of 0.3 ml suspension containing 30 mg of a SiO2/ml saline solution, and were sacrificed 30, 90 and 120 days after instillation; 14 of those sacrificed on days 90 and 120 also received curcumin. The control group included 10 animals which were instilled with a saline solution. Malondialdehyde (MDA), carbonyl proteins (CPs), total thiolic proteins (TPs) and reduced glutathione (GSH) were determined in blood and the lung tissue. The standard technique for pulmonary toxicology developed by Porter was applied to semi-quantitatively assess the histopathological findings. Results: It was found that MDA had increased significantly early on in both biological environments and remained elevated, and adding curcumin proved beneficial, while CPs only increased moderately in the lung tissue without a curcumin impact. Moreover, TPs dropped abruptly, significantly and persistently in the lung tissue and blood, and were not influenced by curcumin. Finally, GSH decreased significantly and intensely in the lung tissue and blood, with curcumin lowering the levels towards those found within the control group. The histopathological examination identified nodules of a cellular type, without any fibrosis, but with spots of associated lipoproteinosis. The early lesions in the airways and vessels were suggestive of a remodeling process. Curcumin diminished the occurrence of alveolitis but not the remodeling process. Conclusions: The study confirms the early onset of oxidative stress in experimental silicosis. It also simultaneously and dynamically researches markers of oxidative stress in blood and the lung tissue. Curcumin proved beneficial on oxidative stress and lesions in the alveolar epithelia, but ineffective in preventing vascular and airway remodeling.

Automated summary

The study aimed to investigate the dynamics of oxidative stress in experimental exposure to silica dust and evaluate histopathological findings before the formation of pulmonary nodules, assessing the effects of curcumin administration. Results showed that markers of oxidative stress were significantly altered by silica dust exposure, with curcumin demonstrating some beneficial effects. However, curcumin was ineffective in preventing vascular and airway remodeling.