Blackberry and Raspberry Attenuate the Increase in Blood Pressure Elicited by Angiotensin II in Mice (P06-054-19).

Abstract

Objectives\nTo examine whether diet supplementation with blackberry or raspberry attenuate angiotensin (Ang) II-induced increase in blood pressure (BP) and decrease oxidative stress in the kidneys of mice.\n\n\nMethods\nTwelve-week male C57BL/6 J mice were fed AIN-93 M diets alone (control and Ang II groups) or supplemented with 10% w/w freeze-dried blackberry (BL\xa0+\xa0Ang II) or raspberry (RB\xa0+\xa0Ang II) powder for eight weeks. At week 4, mice were implanted with subcutaneous osmotic minipumps that delivered 0.9% saline (Control) or Ang II (1 µg/kg body weight/day) for another four weeks. BP was measured weekly by tail-cuff plethysmography and validated by direct measurement at endpoint using a BP catheter. Kidney expression of pro-oxidant enzymes such as NADPH oxidases (Nox) and antioxidant enzymes such as superoxide dismutates (SOD) were also measured. Results were analyzed using ANOVA followed by Tukey-Kramer post-hoc test.\n\n\nResults\nAs expected, Ang II significantly increased systolic BP (SBP; 185\xa0±\xa04, n\xa0=\xa06, vs 132\xa0±\xa02 mmHg, n\xa0=\xa05, P\xa0<\xa00.001) and diastolic BP (124\xa0±\xa04, n\xa0=\xa06, vs 96\xa0±\xa02 mmHg, n\xa0=\xa04, P\xa0<\xa00.001) compared to control. Supplementation with BL and RB significantly attenuated this increase in SBP (143\xa0±\xa07 mmHg, n\xa0=\xa05, P\xa0<\xa00.0001 and 137\xa0±\xa04\xa0mmHg, n\xa0=\xa05, P\xa0<\xa00.0001, respectively) and DBP (100\xa0±\xa06 mmHg, n\xa0=\xa05, P\xa0<\xa00.003 and 90\xa0±\xa03 mmHg, n\xa0=\xa05, P\xa0<\xa00.0001, respectively). Regarding the expression of NADPH oxidases in the kidney, Nox2 was significantly decreased by supplementation with BL (0.68\xa0±\xa00.07-fold, n\xa0=\xa05, P\xa0=\xa00.0005) and RB (0.70\xa0±\xa00.03-fold, n\xa0=\xa05, P\xa0=\xa00.0008) compared to Ang II (1.15\xa0±\xa00.12-fold, n\xa0=\xa05). Nox1 expression was up-regulated by Ang II compared to control (2.03\xa0±\xa00.16 vs 1.00\xa0±\xa00.00-fold, n\xa0=\xa05, P\xa0=\xa00.0001), but this was not prevented by supplementation with either berry. Nox4 expression was not affected by any of the treatments. Lastly, Ang II did not change the expression of SOD1 and SOD2 in the kidney, however, supplementation with RB significantly increased SOD1 (P\xa0=\xa00.02) and SOD2 (P\xa0=\xa00.005) expression compared to the other groups.\n\n\nConclusions\nOur findings indicate that supplementation with BL and RB decrease BP in mice which may be related to a decrease in oxidative stress in the kidney. Studies are underway to further elucidate the mechanism by which BL and RB exert their antihypertensive effects.\n\n\nFunding Sources\nArkansas Biosciences Institute and Lewis Foundation Grant Program.