Author ORCID Identifier

https://orcid.org/0000-0003-2914-5708

Date of Award

6-27-2022

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Nutrition

First Advisor

Dr. Rafaela G. Feresin

Second Advisor

Dr. Desiree Wanders

Third Advisor

Dr. Brett Wong

Abstract

Kidney disease currently affects one in seven American adults, with over 130,000 newly diagnosed adults in 2019 alone. Although there are several risk factors attributed to the development of chronic kidney disease, high blood pressure is considered the second most common risk factor behind diabetes, causing 29% of cases. The elevated levels of angiotensin II associated with high blood pressure can lead to increased levels of oxidative stress, causing damage to the kidneys.The progression of kidney disease can be slowed by following doctors’ orders of prescribed medications to manage the comorbidities of CKD and consuming foods that assist in prolonging renal function through lessening the filtration work required of the kidney.

Many foods associated with prolonged kidney function are plant based with high polyphenol content, and studies show an association between polyphenol intake and reduced risk of CKD.Polyphenols have bioactive properties that target oxidative stress, an underlying driver of CKD development and progression.Raspberries, a concentrated source of polyphenols including ellagitannins and anthocyanins, are often on approved lists for individuals with CKD.

The objective of this study was to examine whether dietary supplementation with raspberries attenuates angiotensin (Ang) II-induced oxidative stress in the kidneys of rats. Eight-week-old male Sprague-Dawley rats were fed an AIN-93M diet (control and Ang II groups) or AIN-93M diet supplemented with 10% w/w freeze-dried raspberry (RB + Ang II) 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 an additional three weeks. Protein expression of antioxidant enzymes in the kidneys was assessed by western blot. Expression of 3-nitrotyrosine was assessed through immunohistochemistry in the kidney. Fibrosis was assessed in kidney tissue through Masson Trichrome Staining. Raspberry supplementation increased the expression of Mas 1 receptor, a receptor heavily involved in anti-inflammatory pathways. Raspberry supplementation also increased the expression of transcription factor NRF2, as well as protein expression of antioxidant enzymes HO-1 and NQO1. Expression of oxidative biomarker 3-nitrotyrosine was increased in the Ang II group and mitigated with the raspberry supplementation, while fibrosis showed no change with raspberry supplementation. Our findings indicate that supplementation with raspberry has the potential to significantly increase the expression of antioxidant enzymes in an animal model of Ang II-induced oxidative stress.

DOI

https://doi.org/10.57709/30238559

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