Effects Of Exercrise On The Spinophilin-Immunoreactive Spine Number In The Subregions Of Hippocampus In The CUS Induced Depression Model Of Rats

Objective: Depression is a kind of mental or emotional disorder with long time depressing mood as main clinical character. The treatment of the disease includes antidepressant medication and electroconvulsive therapy. However,the effects of the above two treatments have limitations and in the process of treatment, patients have to endure great pain. On this basis, the treadmill exercise has triggered widespread concern in the community because of its convenience, effectiveness and simpleness. In order to explore the role of the spinophilin- immunoreactive(Sp-ir) spine number in depression and the impact of treadmill exercise on Sp-ir spine number in depression, the depression model of rats was established with the chronic unpredictable stress(CUS) and then the numberical density and the total number of the Sp-ir spines in the hippocampus in the CUS induced depression model of rats were investigated.Methods : Before the experiment began, the sucrose preference adaptability training was implemented in the male Sprague-Dawley(SD) rats for one week to eliminate the rats which had shown a presence of taste disorder or sugar preference instability. Then, the open-field test was used to exclude the rats with movement disorder. The selected rats were randomly divided into vacuity control group and depression model group. The vacuity control group contained 10 rats, and they were fed as normal. The depression model group rats were given a four-week chronic unpredictable stress and 20 depressed rats were obtained according to the sugar preference results. Then, 20 depressed rats were randomly divided into the model control group and the model running group. The rats in model running group ran on a six-lane motorized treadmill for four consecutive weeks with 20 min each day and five consecutive days each week. At the eighth week, the behaviors of each group rats were tested with the sucrose preference test and open-field test. Then, five rats were randomly sampled from each group. The numerical density and the total number of Sp-ir spines in the hippocampus of each rat were estimated using the immunohistochemical method and the stereological method.Results: 1. After a four-week stress, the body weight, sucrose preference and the total scores on the open-field test of the depression model group were significantly lower than the vacuity control group(p<0.05). More importantly, a four-week running exercise had positive effects on these parameters(p<0.05). 2. The total number of Sp-ir spines in the CA1 area, CA3 area, and DG of the hippocampus in the depression model group were significantly decreased when compared to the vacuity control group, respectively(p<0.05, p<0.05, p<0.05). However, the total number of Sp-ir spines in the CA1 area, CA3 area, and DG of the hippocampus in the model running group rats were significantly increased when compared to the model control group rats, respectively(p<0.01, p<0.01, p<0.01). 3. The numerical densities of Sp-ir spines in the CA1 area, CA3 area, and DG of the hippocampus in the depression model group rats were significantly decreased when compared to the vacuity control group rats, respectively(p<0.01, p<0.01, p<0.01). However, the numerical densities of Sp-ir spines in the CA1 area, CA3 area, and DG of the hippocampus in the model running group rats were significantly increased when compared to the model control group rats.Conclusions: 1. The numerical density and the total number of the Sp-ir spines in the hippocampus were significantly decreased in the depression model of rats. The change of the Sp-ir spine number might be one of the important neurobiological bases in the pathological change of depression. This study might provide a quantitative morphological basis for seeking the new target of depression treatment. 2. The results of the sucrose preference test in the current study indicated that exercise had positive effect on depression. 3. The numerical density and the total number of the Sp-ir spines in the CA1 area, CA3 area and DG of the hippocampus in the depression model rats were decreased, and the exercise had positive effects on the changes of the Sp-ir spines in the depression model rats. We speculate that the effect of running exercise on the Sp-ir spines in the hippocampus of the depression model rats might be one of the important structural bases for the antidepressant effect of running exercise.