Available online at www.scholarsresearchlibrary.com Scholars Research Library European Journal of Zoological Research, 2014, 3 (1):154-157 (http://scholarsresearchlibrary.com/archive.html) ISSN: 2278–7356 154 Scholars Research Library An Investigation of Serum lipid profile in Chronic Mild Stress Rat Model of Depression Mohammad Narimani-Rad, Vahab Babapour* and Morteza Zendehdel Department of Physiology, Faculty of Specialized Veterinary Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran _____________________________________________________________________________________________ ABSTRACT The aim of the present study was to investigate the effects of CMS (chronic mild stress) on serum lipids,whichmay be ininteraction with stress or depressive disorders.Forty to forty-five- day- old laboratory rats were assigned to two groups; control (n: 10) and CMS (subjected to CMS procedure, n: 30). Rats in the control group were reared in single cages without any environmental stress. Rats in CMS were entered the CMS procedure. This protocol consisted of mild unpredictable stressors (intermittent illumination, stroboscopic light, grouping, food or water deprivation, exposure to an empty water bottle, solid cage, cage tilting, etc.). Later, CMS protocol sucrose preference (SP) test was used for the identification of depressed animals. Rats with SP lower than 65% were defined as depressed animals. Blood serum was taken from two groups (control and CMS) for the determination of blood lipids by Elisa kits.The analyzed data showed that serum lipids including total cholesterol, triglyceride, HDL- cholesterol and LDL-cholesterol didn’t lead to a significant difference between two experimental groups. We concluded thatCMS- induced depression cannot affect serum lipid profile in rat model. Further studies with different protocol of depression are required for the identification of possible relations of depression and lipid metabolism. Key words: Chronic mild stress, Depression, Lipid metabolism, Sucrose Preference test. _____________________________________________________________________________________________ INTRODUCTION Research concerningdepression has largely prescribed anti-depressant medicines as well as different levels of effective hormones being studied. However, studies with adverse effects of depression on lipid metabolism are limited[1]. Also, these studies have focused mainly on major depression cases [2]not chronic or depression resulting from mild environmental stresses. So, studies on plasma lipid indices of various models of depression are necessary. Among trusty models of depression, chronic mild stress (CMS) model of depression in rodents has been proposed to model some of the environmental factors that contribute to the introduction of depressive disorders in humans [3, 4]. In the present protocol (CMS), sequential exposure to a variety of mild stressors causes behavioral deficits in different paradigms that measure sensitivity to rewards. Thus, CMS suppresses the consumption of and preference to palatable sweet solution such as sucrose or saccharin [5], and the rewarding properties of food pellets, sweet solutions, and amphetamine as assessed by the place preference conditioning procedure. There is a controversy on the correlation of depression and plasma lipids. In this regards, some of the studies have stated that low total