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Nutr Res. Author manuscript; available in PMC 2011 October 1.
Published in final edited form as: Nutr Res. 2010 October ; 30(10): 714–721. doi:10.1016/j.nutres.2010.09.001.

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Conjugated linoleic acid reduces body weight gain in ovariectomized female C57BL/6J mice
Noriko Kanayaand Shiuan Chen* Division of Tumor Cell Biology, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA

Abstract
Estrogen is an important protective factor against obesity in females. Therefore, postmenopausal women have a higher rate of obesity than premenopausal women, which is associated with agerelated loss of ovary function. It has been reported that a diet containingconjugated linoleic acid (CLA) reduced body weight and body fat mass in the animal model as well as in human trials. We hypothesized that ingestion of CLA would reduce body weight gain in ovariectomized (OVX) female C57BL/6J mice which is a model for postmenopaual women. We further hypothesized that body weight reduction may improve obesity-related complication. To test this hypothesis, the OVXmice fed with a high fat diet containing CLA for 3 months. Mice had significantly reduced body weight gain compared to OVX mice fed with a high fat diet without CLA. While CLA was effective in slowing down of body weight gain of both Sham and OVX mice, analysis of adipocyte size and number suggested different mechanisms for loss of fat tissue in these two groups of mice. CLA treatment did notincrease liver weight and accumulation of fat in the livers of OVX mice. Furthermore, CLA intake did not change insulin resistance. Our results indicate that CLA is functional as an anti-obesity supplement in the mouse model for postmenopausal women, and the anti-obesity effect of CLA is not estrogen-related.

Keywords/phrases Conjugated Linoleic Acids; Obesity; Fatty liver; Mice; Ovariectomy;Postmenopause

1. Introduction
Estrogen is an important protective factor against obesity in the female [1], therefore the overall rate of obesity and related metabolic complications is higher in postmenopausal women compared to premenopausal women [2]. Obesity is a major contributing factor to metabolic syndrome including increased body fat, insulin resistance, dyslipidemia, elevated blood pressureand increased cardiovascular disease [2]. There are large populations of postmenopausal women suffering from these obesity-related issues due to the intake of today's western diet [3] [4]. Since weight gain is a health concern in postmenopausal women, it is important to evaluate the effects of dietary and pharmaceutical approach to the prevention and treatment of obesity in postmenopausal women.Conjugated linoleic acids

*

Corresponding Author: Shiuan Chen, Ph.D., 1500 East Duarte Road, Duarte, CA 91010. Phone: 626-256-4673; Fax: 626-301-8972; schen@coh.org. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergocopyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Kanaya and Chen

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(CLAs) are one class of polyunsaturated fatty acids. When consumed in proper quantities, CLAs areassociated with a variety of health benefits. The most abundant isomer of CLAs is the cis-9/trans-11 form in ruminant meat and dairy products, which displays antiarthrosclerosis effects. Moreover, cis-9/trans-11 CLA exhibits an anti-aromatase activity, resulting in the reduction of estrogen levels and resulted suppression of the proliferation of hormone-dependent breast cancer cells [5]. The CLA...