| PrefacePsychosocial factors have been widely researched, because psychosocial risk factors are highly prevalent and are associated with unhealthy lifestyles, and are associated with socioeconomic factors, and psychosocial factors exert influence health as well as the development, the progression and the prevention of body diseases. Chronic Psychosocial factors negatively influence the development of cardiovascular diseases, triggers cardiovascular events and influences rehabilitation. Harry H have reviewed the evidence linking cardiovascular diseases and psychosocial factors and the possible mechanisms concluded : type A behaviour /hostility, depression and anxiety, work characteristics, and social supports play aetiological and prognostic roles for cardiovascular diseases.To study the effects of Psychosocial factors on cardiovascular diseases , we made animal models of chronic stress and observed the ultrastructural changes of myocardium and aorta to explore the relation between cardiovascular lesion and chronic stress, we also detected the expression of heat shock protein70 ( HSP70) to study the relation between lesion factors and protection factors, to provide basis for cardiovascular protection after psychosocial stress and exploitation of new way to protect cardiovascular system in clinic.Materials1. Experimental animals: Male Wistar rats weighting about 195 - 240gwere purchased from the center of experimental animals in China Medical University.2. Experimental reagents; Rabbit anti - HSP70 and SABC kit( Boster Biotechnology Co. LTD. )3. Experimental instruments: Electrophysiological apparatus , MetaMorph/ Cool Snapfx/Ax70 image analysis system, JEM 1200EX transmission electron microscope.Methods1. Animal groupingExperimental rats were housed for 7 days to adapt the conditions of the lab. Then their behavior were observed by Open - field test and they were divided into experimental group and control group randomly, 12 rats and 11 rats respectively.2. Stress processExperimental group were fed separately one rat in one box. from 1 ~ 21 days, accept various types of stresses. The control group were fed in two boxes, no stress from 1 -21 days.3. Make Sections and measureOn 22th day killed all the rats. Four small pieces of tissue were immediately dissected from cardiac apex of left ventricles and aorta respectively . Sections for transmission electron microscope and immunohistochemistry were make respectively . Ultrastructure of myocardium and aorta were observed. Used immunohistochemistry method to measure the expression of HSP70 protein in myocardium and aorta.4. Image analysisTo select one sheet each rat to analyze optical density ( OD) average of Hsp70.5. statistical treatmentTo analyze the date with SPSS11.5 software.Results1. Weight and the results of Open - field testAfter 21 days stress, weight, ambulation, rearing and grooming decreased and stopping time in center, defecation increased in experimental group.2. Ultrastructure of myocardium and aortaThe ultrastructural changes of the myocardium were observed in rats of chronic stress group, including stroma edema of myocardial cells, myofibril disorder, mitochondrion degeneration, intercalated disc dissociation, endothelium edema . Aorta in rats of chronic stress group, smooth muscle cell (SMC) of contractile phenotype were converted to that of synthetic phenotype, and migration and mitochondrion degeneration of SMC also happened, some endothelium cells were lost. The ultrastructure in rat of control group was essentially normal.3. HSP70 expression in myocardium and aorta.Hsp70 expressed obviously in experimental group , and the expression of Hsp70 in myocardium and aorta in experimental group were higher than those in control group(t=7.50,p<0.001) (t =2.67,p <0.05).DiscussionThe open - field test is used to detect the priming and investigating behaviors, strain level and the vigilance in new environment. Acute stress can enhance the activity of animal, along with the extension, the behavior activity gradually reduce, and the behavior performance transfer from excitement, anxious appearance to repression and depression. After 21 days stress, weight, ambulation, rearing and grooming decreased and stopping time in center, defecation increased in experimental group. These changes show the increasing tensity, lose of interesting and decreasing of cognitive ability. These performances had the most similarity with psychomotor inhibition and change of behavior and interesting of human being under chronic psychosocial stress which can show the chronic stress model was made successfully.
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