Effects Of CMS On The Expression Of Disc1 In The Hippocampus In Mice

IntroductionMajor depressive disorder (MDD) is one of the most common psychiatric disease and is characterized by repeatedly relapse. Life event, especially chronic unpredicted stress plays an important role in the onset and development of MDD. Chronic mild stress, as a widely used animal model of MDD, can cause damage to brain, especially affect the structure and function of the hippocampus, however the pathophysiology of MDD remains unclear. Accumulating genetic evidence supports that MDD, bipolar disorder and schizophrenia have some common susceptibility genes, including DISC1. DISCI functions as a molecular scaffold, interacting with multiple protein required for neuronal migration, neurite outgrowth, signal transduction, cAMP signaling, cytoskeletal modulation and translational regulation. This study investigated the effects of chronic mild stress on the expression of Disc1, the mechanisms of brain damage and neuron protection in MDD causing by chronic mild stress is discussed.Materials1. Experimental animals:Male ICR mice (n=14) weighting about 22-25g were purchased from the center of experimental animals in China Medical University.2. Experimental reagents:Rabbit polyclonal to DISCI (ab82014); HRP-Goat anti Rabbit; SABC kit (Boster Biotechology co.LTD); DAB kit (Boster Biotechology co.LTD). 3. Experimental instruments:Multispectral imaging system (UVP, U.S.A); Double Beam UV/VIS spectro (HITACHI, Japan); High-speed Refrigerated centrifuge (HITACHI, Japan); Meta Moph/Cool SnpPfx/Ax70 computer image analysis system.Methods1. Mice were housed for 7 days to adapt the conditions of the lab.2. Following the final baseline sucrose consumption, the animals were divided into two matched groups and placed in separate rooms. The differences between the baseline sucrose consumption of the two groups was not statistically significant. The CMS protocol started one day after the last sucrose test of the adaptation period and lasted for 5 weekly cycles that consisted of continuous stressors alternating during the day. The stressors were:paired caging, tilted cage (45°), food and water deprivation, restricted access to food, exposure to an empty bottle, wet cage and stroboscopic illumination. The body weight of each animal was measured once per week every Monday morning.3. The Discl expression in the CA1, CA3 and DG regions of mice hippocampus were detected by immunohistochemistry and western blotting of special antibody.Results1. Sucrose intake and preference:CMS cause a gradual decrease in the consumption and preference of 1% sucrose solution (P<0.05).2. Body weight and open field test:Stressed animals gained body weight more slowly than controls (P＜0.01). In 5 min open field test, there was no significant differences in total activity compared with non-stressed control animals (P>0.05).3. The expression of Disc1 in the hippocampus of mice:Disc1 was located in nucleus, evaluation of Disc1 immunohistochemical showed a significant increased in CA1, CA3 region and DG compared with control group (P<0.05). Similar to the immunohistochemical, we also observed a up-regulation of Disc1 protein in the chronic stress mice analyzed by Western blotting (P<0.05).Conclusion1. Compared to control group, the expression of Disc1 in chronic stress mice in hippocampus CA1, CA3 region and dentate gyrus was significantly decreased.2. Disc1 is possible involved in the pathophysiology of depression.