The Sterological Studies Of The Effects Of Exercise On The White Matter And The Myelinated Fibers Of The White Matter In Depression Rats

PART ONEESTABLISHMENT OF THE RAT MODEL OF DEPRESSION AND INVESTIGATION OF THE EFFECTS OF EXERCISE ON THE BEHAVIORS OF THE RAT MODEL OF DEPERSSIONObjective:To establish chronic unpredicted stress(CUS) rat model of depression, and investigate both the changes of the behaviors of CUS rat model of depression and the effects of running exercise on those changes in CUS rat model of depression, in order to provide theroetical basis for running exercise induced prevention of depression.Methods:Male SD rats were adapted to the environment for one week. Then, male SD rats were randomly divided into the control group (10 rats) and depression model group (30 rats). From the second week, the depression rats were made by giving rats the chronic unpredicted stress for four weeks. The behaviors were tested with the sucrose preference test, the forced swimming test and the open-field test. Twenty successfully made depression rats were randomly divided into the control depression group (10 rats) without running and the running depression group (10 rats). The running depression group rats ran for four weeks. After 4-week running exercise, the behaviors were tested again with the sucrose preference test, the forced swimming test and the open-field test.Results:After 4-week stress,when compared to the control group, the body weight, the sucrose preference and the scores of the open-field test were significantly decreased in the depression model group, and the immobility time in the forced swimming was significantly increased in the depression model group (p< 0.05). After 4-week running exercise, when compared to the control depression group, the sucrose preference was significantly increased in the running depression group rats (p<0.05), but the body weight, the scores of the open-field test and the immobility time in the forced swimming was not different between the control depression rats and the running depression group rats (p>0.05).PART TWOTHE STEROLOGICAL STUDIES OF THE EFFECT OF EXERCISE ON THE WHITE MATTER AND THE MYELINATED FIBERS OF THE WHITE MATTER IN DEPRESSION RATSObjective:To investigate the changes of the white matter and the myelinated fibers in the white matter of CUS depression model rats and the effects of running exercise on those changes in CUS depression model rats with the stereological method, in order to study the morphological basis for the effects of running exercise on depression rats.Methods:5 rats were randomly sampled from the control group, the control depression group and the running depression group. Each hemisphere was then coronally cut into serial 1-mm thick parallel slabs, starting randomly at the rostral pole. The cut slabs were photographed under anatomical microscope. Four tissue blocks were randomly sampled form each white matter in order to making electron microscopy specimens. The white matter volume, the total length of the myelinated fibers, the total volume of the myelinated fibers and the total volume of the myelin sheaths in the white matter were estimated using the stereological methods.Results:The total white matter volume, the total length of the myelinated fibers in the white matter, the total volumes of the myelinated fibers, the myelinated fiber axons and the myelin sheaths in the white matter, the outer diameter of the the myelinated fibers, the thickness of the myelin sheaths in the white matter of the control depression group were significantly less than those of the control group (p< 0.05). The inner diameter of the the myelinated fibers in the white matter of the control depression group were not significantly different from that of the control group (p>0.05). When compared to the control depression group, the total white matter volume, the total length of the myelinated fibers in the white matter, the total volumes of the myelinated fibers, the myelinated fiber the axons and the myelin sheaths in the white matter, the outer diameter of the the myelinated fibers, the thickness of the myelin sheaths in the white matter of the running depression group were significantly increased (p<0.05). The inner diameter of the the myelinated fibers in the white matter of the running depression group were not significantly different from that of the control depression group (p>0.05).CONCLUSIONS1. Running exercise could effectively improve anhedonia of depression rats.2. Running exercise could increase the total white matter volume, the total length of the myelinated fibers in the white matter, the total volumes of the myelinated fibers, the myelinated fiber axons and the myelin sheaths in the white matter, the outer diameter of the the myelinated fibers, the thickness of the myelin sheaths in the white matter of the depression rats.3. The protective effects of running exercise on the white matter of depression rats might be one of the structure bases for the exercise induced treatment of depression.