ABC | Volume 113, Nº5, November 2019

Original Article Sousa et al. Antioxidant effect of rat environmental enrichment Arq Bras Cardiol. 2019; 113(5):905-912 Figure 2 – Baseline levels of mean arterial blood pressure (MAP, mmHg) in hypertensive (2K1C) and normotensive rats (Sham) subjected to environmental enrichment (EE) and standard condition (St). Direct measurements of MAP were performed on the 4th weeks after 2K1C surgery. Letters (above the bars) indicate significant differences. (a) The difference in relation to the Sham-St; (b) Difference in relation to the Sham-EE analysed by Kruskal-Wallis test, followed by Dunn’s post-test a (p < 0.05) (n = 7 in each group). Data are expressed as median, minimum and maximum value. 200 150 a,b Sham-St Sham-EE 2K1C-St 2K1C-EE MAP (mmHg) 100 50 0 Antioxidant defences and oxidative stress biomarkers Superoxide dismutase (SOD) activity was evaluated via the enzyme’s capacity to inhibit pyrogallol autoxidation (absorbance of 570 nm). 20 Catalase activitywas determined through the speed of H 2 O 2 reduction (absorbance of 240 nm). 21 Carbonyl protein determination methods (absorbance of 370 nm) were based on a previous publication. 22,23 Lipid peroxidation was evaluated with the thiobarbituric acid‑reactive substances (TBARS) assay (absorbance of 535 nm). 24 Total protein was quantified with the Bradford method. 25 Statistical analysis Results are reported as means ± SD or median, minimum andmaximumvalue. Normality was checked using Kolmogorov- Smirnov. Data were then analysed with one-way ANOVA test, followed by a post-hoc Newman-Keuls test or Kruskal-Wallis test, followed by Dunn’s post-test. Statistical analyses were performed in GraphPad Prism. Significance was set at p < 0.05. Results Effects of environmental enrichment on mean arterial pressure To evaluate if environmental enrichment reduces blood pressure in hypertensive rats, we compared MAP across our four experimental groups. The 2K1C-St group had significantly higher MAP 147.0 (122.0; 187.0) mmHg, p < 0.05, than Sham-St 101.0 (94.0; 109.0) mmHg and Sham-EE 106.0 (90.8; 117.8) mmHg. The four groups did not differ significantly in heart rate (Figure 2). Effects of environmental enrichment on oxidative stress marker in the ventrolateral medulla Superoxide dismutase activity in the ventrolateral medulla was higher for 2K1C-EE than for 2K1C-St. Additionally, catalase activity was higher in 2K1C-EE than in all other groups. We observed increased TBARS value in 2K1C-St compared with Sham groups, but reduced activity in 2K1C-EE compared with 2K1C-St (Table 1). Effects of environmental enrichment on oxidative stress marker in the left ventricle Overall, TBARS concentration was higher in both hypertensive groups than in Sham groups. Catalase activity was lower in 2K1C-St than in Sham-EE. Carbonyl protein and SOD were similar across all experimental groups (Table 2). Effects of environmental enrichment on oxidative stress marker in the right kidney We observed increased SOD activity in environmentally enriched groups (2K1C-EE, Sham-EE) compared with standard groups (2K1C-St, Sham-St). The 2K1C-EE group had higher carbonyl protein and lower TBARS concentration than the 2K1C-St group (Table 3). Effects of environmental enrichment on oxidative stress marker in the left kidney Furthermore, SOD activity was higher among 2K1C‑EE than 2K1C-St animals. Catalase activity was lower in hypertensive groups (2K1C-St and 2K1C-EE) than Sham groups (Sham‑St and Sham-EE). Carbonyl protein activity and TBARS concentration did not differ significantly across experimental groups (Table 4). Discussion As found in other studies, standardly housed hypertensive rats exhibited MAP values different than standardly housed normotensive controls. Importantly, this study is the first to demonstrate similar MAP values between normotensive and enriched hypertensive rats. This outcome is likely due to the 907