(P04-012-24) Berry-Rich Diet Improves Systolic Blood Pressure and Intestinal Permeability in Angiotensin II-Treated Rats

Objectives: Increase in intestinal permeability (IP) is associated with high blood pressure (BP). Blackberries (BL), raspberries (RB), blueberries (BB), and strawberries (SB) are commonly consumed fruits and widely studied for their health benefits. Thus, the objective of this study was to evaluate the effects of a berry-rich diet on BP and intestinal barrier function in angiotensin (Ang) II-treated rats.

Methods: Eight-week-old male Sprague-Dawley rats were fed an AIN-93M diet alone (control (CON), Ang II, and Losartan (LOS; 20 mg/kg/BW) groups) or supplemented with 10% w/w freeze-dried berries (equal parts BL, RB, BB, and SB; Berry group) for 8 weeks. Rats were implanted with subcutaneous osmotic minipumps delivering 0.9% saline (CON) or Ang II (270 ng/kg/BW/min; Ang II, LOS, and Berry groups) at week 4. Blood pressure was measured weekly using tail-cuff plethysmography. Intestinal permeability was measured by FITC-dextran (600 mg/kg BW, oral gavage) assay. Protein expression of tight junctions (TJ) in the proximal and distal colon was assessed using Western Blot. Data were analyzed using t-tests, ANOVA, or mixed model as appropriate.

Results: Systolic BP increased in Ang II at week 6 compared to CON (p = 0.04), LOS (p = 0.004), and Berry (p = 0.048) groups, and remained significantly elevated through week 8. FITC-dextran passage across the intestinal barrier was significantly higher in Ang II at week 8 versus CON (p = 0.004), LOS (p = 0.001), and Berry (p = 0.006). Expression of TJ proteins including claudin (CLDN)-1 was significantly lower in the proximal colon in Ang II (p = 0.04), LOS (p = 0.006), and Berry (p = 0.01) versus CON at week 8, but not in the distal colon. Conversely, zonula occludens (ZO)-1 expression was lower in the distal colon in Ang II (p = 0.006), LOS (p = 0.005), and Berry (p = 0.02) versus CON at week 8, but not in the proximal colon.

Conclusions: We demonstrate that a berry-rich diet protects against increases in systolic BP in Ang II-treated rats and reduced IP as measured by FITC-dextran assay. Ang II appears to modulate TJ protein expression differently across the colon; however, further analyses are ongoing.

Funding Sources: The Agriculture and Food Research Initiative (grant no. 2023-67011-40351/project accession no. 1030787) from the USDA National Institute of Food and Agriculture.