Investigation of physiopathological changes caused by stress and exercise in the brain and behaviours

2. ABSTRACT INVESTIGATION OF PHYSIOPATHOLOGICAL CHANGES CAUSED BY STRESS AND EXERCISE IN THE BRAIN AND BEHAVIOURS. Stress can be defined as the factors that disrupt the homeostasis. These include the internal factors such as memory and the factors such as threats, which are developed by the brain-body reaction against the environmental stimulus. In the present of stressors, a complex stress response is generated involving the endocrine, nervous and immune systems to maintain homeostasis. As indicated in the studies conducted previously, stressors can cause health problems on the individual depending on the duration. Exercise is explained as the activity that is conducted and repeated regularly to improve the physical condition to preserve that condition. Besides the physical beneficial effects of the exercise, its physiological and psychological beneficial effects have been provided by the studies conducted. The cognitive, affective and the sexual effects of the stress and exercise were investigated in this study. Besides the behavioral analyses applied on the experimental groups, the changes were investigated for the neurotransmitter and neuropeptides' receptors, which were accepted as the direct or indirect effect mechanism accepted widely to occur through. Thus, a detailed explanation of the underlying cellular mechanisms regarding the effects of the stress and exercise on the above mentioned subjects were aimed. Sexually mature (3-month-old) 40 male Sprague-Dawley rats were used in this study. The rats were divided into four groups as control, exercise, stress and stress+exercise groups, each including 10 animals. A restraint apparatus was used to induce the chronic stress for the stress model. The behavioral analyses were conducted and recorded for all groups at indicated times throughout the study. At the end of the experiments, brain samples were collected for the analyses of immunofluorescence and gene expression. Kisspeptin expressions were investigated in the hypothalamic arcuate nucleus (ARC) by using the immunofluorescence technique. In addition, the expression of the genes related with stress and exercise was investigated in the regions including hypothalamus, hippocampus, prefrontal cortex and corpus striatum were investigated by Real Time Polymerase Chain Reaction (RT-PCR). During the behavioral tests, significant increases in the anxiety and depression parameters were observed in immobility induced stress group. Besides, the sexual behavior tests revealed that the stress-induced group had significantly reduced sexual performance with ejaculation. However, when these animals were exercised, it was observed that the data were improved. The indicated changes in kisspeptin and gene expressions in the arcuate nucleus have been revealing the possible underlying mechanisms causing the behavioral changes. As the conclusion, the decline in the affective, cognitive and the sexual functions due to the stress was improved by exercise and the informative knowledge regarding genetic and cellular mechanisms regarding the effects of exercise were obtained. Key Words: Stress, exercise, brain, behavior.