Investigation on Serum Hormonal Parameters (Ghrelin, Corticosterone, Insulin, T-3 and T-4) in Chronic Mild Stress Rat Model of Depression

Abstract

The aim of present study was to investigate the effects of depression induced with chronic mild stress (CMS) protocol on serum hormones (ghrelin, corticosterone, insulin, T-3 and T-4) which is in interaction with stress or depressive disorders. Forty-five 40-45 d 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.). After CMS protocol sucrose preference (SP) test was used for the identification of depressed animals. Rats with lower than 65% SP were defined as depressed animal. Blood serum was taken from two groups (control and CMS) for the determination of blood hormonal variables by Elisa kits. Analyzed data showed a significant elevation in ghrelin, corticosterone, and insulin levels for CMS group (depressed animals) in comparison with control group, as elevation was very significant for corticosterone. There was not any significant change for T-3, whereas decreased T-4 was observed for CMS groups when compared with the control. It was concluded that chronic mild stress induced depression can cause ghrelin, corticosteroid, and insulin increases, and T-4 decreases. Mentioned effects of CMS induced depression on hormonal indices (with exception to thyroid hormones), can be similar with effects of major depression.