MSpace - DSpace at UofM >
Faculty of Graduate Studies (Electronic Theses and Dissertations) >
FGS - Electronic Theses & Dissertations (Public) >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1993/4085

Title: The effects of conjugated linoleic acid (CLA) isomers on obesity-related hypertension: insight into possible mechanisms involving adipocyte function
Authors: DeClercq, Vanessa
Supervisor: Zahradka, Peter (Human Nutritional Sciences) Taylor, Carla (Human Nutritional Sciences)
Examining Committee: Aukema, Harold (Human Nutritional Sciences) Smyth, Don (Pharmacology and Therapeutics) Belury, Martha (Ohio State University)
Graduation Date: October 2010
Keywords: obesity
hypertension
conjugated linoleic acid
adipocyte
adipokines
Issue Date: 30-Aug-2010
Abstract: Enlargement of adipocytes in obesity leads to alteration in adipokine production and these changes are linked to the development of obesity-related cardiovascular diseases. Adipokines specifically associated with obesity-related hypertension include angiotensinogen and adiponectin. Conjugated linoleic acid (CLA) has been reported to reduce blood pressure in obese insulin-resistant rats, but its mechanism of action has not been identified. The objective of this study was to determine whether CLA’s ability to improve obesity-related hypertension involves reducing adipocyte size and altering adipokine production. Fa/fa Zucker rats (6 or 16 week old) were fed diets containing CLA isomers for 8 weeks. The trans(t)10,cis(c)12-CLA isomer reduced adipocyte size in both younger and older rats. Despite beneficial changes in cell size of rats fed the t10,c12-CLA isomer, there were no changes in the renin-angiotensin system or pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 or the anti-inflammatory cytokine IL-10. In contrast, the t10,c12-CLA isomer increased adiponectin levels both in the circulation and in adipose tissue. This was associated with increased phosphorylation of endothelial nitric oxide synthase (eNOS) in adipose tissue and aorta. Direct treatment of CLA isomers in cultured endothelial cells did not increase eNOS phosphorylation but increases were observed with adiponectin treatment. In vivo, infusion with adiponectin increased eNOS phosphorylation in adipose of fa/fa Zucker rats in parallel with improvements in blood pressure. Similarly, when circulating levels of adiponectin increased in rats fed the t10,c12-CLA isomer diet, blood pressure was also attenuated. In younger rats, both the t10-c12 and c9,t11-CLA isomers were significantly different from the control group at week 8, however, only the t10,c12-CLA isomer was comparable to the commonly used anti-hypertensive medication captopril. In conclusion, the beneficial effects of the t10,c12-CLA isomer on blood pressure may in part be due to its ability to reduce the number of large adipocytes in vivo, thus increasing the production of adiponectin which subsequently activates vascular eNOS.
URI: http://hdl.handle.net/1993/4085
Appears in Collection(s):FGS - Electronic Theses & Dissertations (Public)

Files in This Item:

File Description SizeFormat
THESIS - 2010-08-10.pdf2.83 MBAdobe PDFView/Open
View Statistics

Items in MSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! MSpace Software Copyright © 2002-2010  Duraspace - Feedback