Raspberry Consumption Decreases NOX4 Expression and Increases Antioxidant Enzymes in Lungs of Angiotensin II-Infused Rats

Abstract

Objectives To determine whether a diet supplemented with red raspberry (RB) is effective at reducing angiotensin (Ang) II-induced oxidative stress in the lungs of Sprague Dawley (SD) rats. Methods Eight-week-old male SD rats were fed an AIN-93M diet alone (control and Ang II) or supplemented with 10% w/w freeze-dried RB powder for a total of seven weeks. At week 4, SD rats were implanted with subcutaneous osmotic minipumps for delivery of 0.9% saline (control) or Ang II (270 ng/kg body weight/day). Following 3 weeks of infusion, rats were sacrificed, and lungs were collected for analysis. Protein expression of the pro-oxidant enzyme, NADPH oxidase (NOX) 4, and antioxidant enzymes superoxide dismutase 1 (SOD1), catalase, heme oxygenase-1 (HO-1), and NADPH quinone dehydrogenase 1 (NQO1) were assessed by western blot. Results were analyzed by one-way ANOVA followed by Tukey post-hoc test. Results were normalized to control and presented as means ± standard deviation. Results RB supplementation significantly increased the expression of antioxidant enzymes, including, SOD1 (1.34 ± 0.16, n = 5, vs 1.11 ± 0.13-fold, n = 5, P = 0.04) and catalase (1.50 ± 0.28, n = 5, vs 0.79 ± 0.20-fold, n = 5, P = 0.008), when compared to Ang II alone. Compared to control, however, RB significantly increased SOD1 (1.00 ± 0.05-fold, n = 4, P = 0.004) while catalase did not (1.00 ± 0.40, n = 4, P = 0.07). Similarly, HO-1 (1.66 ± 0.82, n = 5, vs 0.75 ± 0.13-fold, n = 4, P = 0.046) and NQO1 (2.13 ± 0.19, n = 4, vs 1.26 ± 0.14-fold, n = 5, P < 0.0001) were greater in the RB supplemented rats in comparison to Ang II alone. Additionally, RB significantly increased NQO1 (1.00 ± 0.16, n = 4, P < 0.0001) but not HO-1 (1.00 ± 0.43-fold, n = 4, P = 0.22) when compared to control. RB supplementation also decreased the expression of NOX4 (0.77 ± 0.38, n = 5, vs 1.41 ± 0.30-fold, n = 5, P = 0.02) in comparison to Ang II alone. Conclusions Our results suggest the potential for red raspberries to decrease oxidative stress within the lung tissue. As investigations into whole food dietary treatments in lung conditions are essentially non-existent, future work will aim to determine the potential for raspberries to serve as a complementary therapy in these conditions. Funding Sources This work was funded by the Agriculture and Food Research Initiative (grant no. 2019–67,017-29,257/project accession no. 1,018,642) from the USDA National Institute of Food and Agriculture.