Paeoniflorin Attenuated Oxidative Stress in Rat COPD Model Induced by Cigarette Smoke

Abstract

Paeoniflorin (PF), a monoterpene glucoside, might have an effect on the oxidative stress. However, the mechanism is still unknown. In this study, we made the COPD model in Sprague-Dawley (SD) rats by exposing them to the smoke of 20 cigarettes for 1 hour/day and 6 days/week, for 12 weeks, 24 weeks, or 36 weeks. Our findings suggested that smoke inhalation can trigger the oxidative stress from the very beginning. A 24-week treatment of PF especially in the dosage of 40 mg/kg·d can attenuate oxygen stress by partially quenching reactive oxygen species (ROS) and upregulating antioxidant enzymes via an Nrf2-dependent mechanism.

Figure 1

Effects of PF on pulmonary function of rats of different stages. The histograms of FEV0.1/FVC% (a), PEF (b), and MMEF (c), respectively, indicated successful formation of COPD. Data were mean ± SEM (n = 8). ^∗ P < 0.05, ^∗∗ P < 0.01, compared with the Normal Control group. ^# P < 0.05, ^## P < 0.01, compared with the COPD model group. ^∧∧ P < 0.01, compared with Budesonide group.

Figure 2

Histological analysis and airway inflammatory scores revealed typical pathological features. The right lung was removed for histopathologic examination using hematoxylin and eosin staining. (a) Normal Control (NC) group. (b) COPD model group. (c) Budesonide group. (d) Paeoniflorin middle-dose group. Original magnification, ×200. 1–3 presented the histology of lung at three stages, 12 weeks, 24 weeks, and 36 weeks, respectively. (e) The severity of airway inflammation scores. ^∗∗ P < 0.01, compared with the Normal Control group. ^# P < 0.05, ^## P < 0.01, compared with the COPD group. ^∧ P < 0.05, compared with Budesonide group.

Figure 3

Levels of HO-1, SOD, MDA, ROS, and T-AOC in rat serum. In this study, we used Elisa to detect the level of oxidants like ROS (d) and MDA (c) as well as antioxidants including HO-1 (a), SOD (b), and T-AOC (e) in rat serum. ^∗ P < 0.05, ^∗∗ P < 0.01, compared with the Normal Control group. ^# P < 0.05, ^## P < 0.01, compared with the COPD group. ^∧ P < 0.05, ^∧∧ P < 0.01, compared with Budesonide group.

Figure 4

Regulation of mRNA expressions of antioxidant enzymes including HO-1, γ-GCS, and SOD via an Nrf2 dependent mechanism. PF of all three dosages significantly increased the total amount of mRNA expression of antioxidant enzymes by means of upregulating ATF-4 (a) and Nrf2 (b) mRNA expressions as well as HO-1 (c), SOD (d), and γ-GCS (e) in the lung tissue. ^∗ P < 0.05, ^∗∗ P < 0.01, compared with the Normal Control group. ^# P < 0.05, ^## P < 0.01, compared with the COPD group. ^∧ P < 0.05, ^∧∧ P < 0.01, compared with Budesonide group.

Figure 5

Estimate of protein expressions throughout Western blot. GAPDH was used as the loading control. The optical density for target protein is shown as a proportion of GAPDH optical density. Here we detected the total amount of protein expressions of ATF-4 (a), Nrf2 (b), HO-1 (c), SOD (d), and γ-GCS (e) in the lung tissue. ^∗ P < 0.05, ^∗∗ P < 0.01, compared with the Normal Control group. ^# P < 0.05, ^## P < 0.01, compared with the COPD group. ^∧ P < 0.05, ^∧∧ P < 0.01, compared with Budesonide group.