Effects of Raspberry Consumption on Angiotensin II-induced Hypertension and Expression of Antioxidant and Pro-oxidant Enzymes in the Brain of Rats

Background: Angiotensin (Ang) II is a potent vasoconstrictor and inducer of oxidative stress. The subfornical organ (SFO) and organum vasculosum of lamina terminalis (OVLT) are circumventricular organs that lack the blood brain barrier and therefore are prone to oxidative stress. Raspberries (RB) are rich in polyphenols which have been shown to have great antioxidant capacity. Thus, the objective of this study is to determine whether RB mitigates blood pressure (BP) increases, attenuates the expression of pro-oxidant enzymes, and increases the expression of antioxidant enzymes induced by angiotensin Ang II in the SFO and OVLT of Ang-II infused rats. Methods: Sprague Dawley rats were fed a diet with or without 10% w/w freeze-dried RB for seven weeks. At week 4, rats were implanted with subcutaneous osmotic minipumps that delivered 0.9% saline (Control) or Ang II (270 ng/kg body weight/min) for another three weeks. BP was measured at weeks 4, 5 and 6. Animals were sacrificed, and brains excised and stored for later analysis. Protein expression of NADPH oxidases, NOX2, NOX4, as well as superoxide dismutase (SOD) 1 and SOD2 were measured in the SFO and OVLT. Results: Although not significantly, Ang II increased systolic BP while RB supplementation attenuated this increase. In the SFO, Ang II increased NOX2 and NOX4 expression. RB supplementation attenuated the increase in NOX2 expression. Ang II increased SOD1 while decreasing the SOD2 expression. RB supplementation increased SOD1 compared to control. Similarly, in the OVLT, Ang II increased NOX4 expression compared to control; however, no other significant changes were observed. Conclusion: Our preliminary findings suggest that RB may attenuate the Ang II-induced increases in BP and oxidative stress in the SFO. Future investigations are warranted to elucidate these effects. Funding Sources: This work was supported by the Agriculture and Food Research Initiative (grant no. 2019-67017-29257/project accession no. 1018642) from the USDA National Institute of Food and Agriculture