Date of Award

Fall 8-31-2016

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Food Science and Human Nutrition

Advisor

Dorothy Klimis-Zacas

Second Committee Member

James Weber

Third Committee Member

Jay Ye

Abstract

The goal of this study is to investigate the effect of a wild blueberry diet on pathology of the metabolic syndrome (MetS) by examining the morphological and biochemical properties of the liver and aortic tissue in the obese Zucker rat (OZR), a valid model of the MetS.

At 8-weeks of age, 16 Obese Zucker ras (OZR) and 16 lean Zucker rats (LZR) littermates were placed on either an 8% w/w wild blueberry (WB)-enriched isocaloric diet or an isocaloric control (C) diet for a duration of 8-weeks. At 16-weeks of age, the tissues of interest were harvested for the study. The morphological features for hepatic steatosis and glycogen were assessed utilizing a unique series of stains and were analyzed through image analysis and a histopathological review by a pathologist. The accumulation of hepatic triglyceride (TG) was also evaluated for the assessed. For the assessment of morphological features of the thoracic aorta, a series of unique stains were utilized and further analyzed through the use of image analysis to detect collagen and connective tissue, the thickness of the tunica media, the number of nuclei, and the presence of glycosaminoglycans.

A significant increase in hepatic steatosis was found in the OZR compared to the LZR after image analysis and histopathological evaluation of the Hematoxylin and Eosin (H&E) stain, the Oil Red O (ORO) stain, and hepatic TG concentration. Although non-significant, image analysis of the hepatic triglycerides using the ORO stain found a trend for a decrease in hepatic TG content in the OZR-WB group compared to the OZR-C. Image analysis of the Periodic Acid-Schiff (PAS) stain revealed a significant increase in hepatic glycogen in the OZR compared to the LZR. Although non-significant, the LZR-WB and OZR-WB tended to have a greater amount of glycogen than the LZR-C and OZR-C groups respectively.

Regarding the morphology of the aortic tissues, there were no significant differences found due to rodent model or due to diet after evaluating for connective tissue, medial width, number of nuclei, and glycosaminoglycans. The LZR-WB and OZR-WB groups tended to have less medial width, and a lower percentage of glycosaminoglycans compared to the LZR-C and the OZR-C respectively. Additionally, although non-significant, there was a trend for elevated number of nuclei in the OZR-WB group compared to all other groups. In conclusion, consuming wild blueberries has the potential to alter the morphology of hepatic and aortic tissues and confirms that the OZR continues to act as a reliable model of the MetS.

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