Introduction: Thymus is the central lymphoid organ responsible for proper immune cell maturation, hence ensuring functional T cell repertoire. Stress induces elevated levels of hormones that profoundly alter immune response. Susceptibility to physiologically synthesised and exogenously applied glucocorticoids make thymus an ideal substrate for anatomical and morphological analysis. Aim: Our research aimed to investigate the impact of endogenous and exogenous glucocorticoids on thymus weight level. Material and methods: Experimental procedure was conducted on male Wistar rats, 12 in total, divided into 2 groups - control and experimental. Latter was exposed to two kinds of stressors. Acute stress included immobilization with exposure to the predator's odor. Chronic social stress included rotation of the animals held in pairs. On the 11th day of the experimental procedure, half of the experimental group received dexamethasone treatment (impact of endogenous + exogenous glucocorticoids) while the other half did not (impact of endogenous glucocorticoids). After the experiment, animals were sacrificed and their thymuses were obtained and measured. For statistical analysis, ANOVA was used to test differences between groups and LSD test for each group testing. Results: Results showed statistically significant differences between the thymus mass of different groups (F=4.336, p=0.048). The part of the experimental group that received dexamethasone had a smaller thymus weight level compared to the part of the experimental group that received no treatment (p=0.024). No statistically relevant results were obtained after comparing thymus masses from impact of endogenous glucocorticoids and control group (p>0.05). Conclusion: Exogenous glucocorticoids induce morphological changes in thymus which are observed in decreased weight level. Stress induced thymus apoptosis, but it was not sufficient to lead to decrease in thymic mass. Our further experiments will put emphasis on understanding of morphological and anatomical changes caused by stress.
Introduction: Posttraumatic stress disorder (PTSD) represents a mental disorder that occurs after life threatening situations. Animal models in psychiatry studies represent a base from which results and conclusions can be translated to human population. Amygdala and hippocampus are important neuroanatomical substrates possibly relevant to PTSD pathogenesis. Aim: The aim of study was to investigate volumetric changes that occur in hippocampus and amygdala related to PTSD animal model. Material and methods: Experiment was conducted on adult male Wistar rats. They were two groups, experimental and control. Experimental paradigm lasted for 31 days during which animals were exposed to acute and chronic stress. Acute stress was performed on the first day and ten days later. In between, animals were exposed to chronic social stress by pair rotations. Before second acute stress exposure, experimental group was divided in two subgroups from which one received dexamethasone dose. After the experiment ended, animals were sacrificed and the brain was extracted. Following the freezing process, brain tissue samples were cut and prepared for microscopy using. This was followed by volumetric analysis of hippocampus and amygdala. Measurements were performed bilaterally using Image Tool 3.0 Software. Results: Results showed volumetric changes in these structures. Hippocampus had smaller volume in the experimental subgroup without dexamethasone (x̄ = 0.6144) compared to the control group (x̄ = 0.9688). Amygdala, as well, had smaller volumes in same subgroup compared to the control (x̄ = 10.0156 compared to x̄ = 11.5041). Conclusion: Our study provided results in agreement with several previous studies on rodents and contributes to the assumption that hippocampus and amygdala have significance in PTSD etiology. Further goal is to expand our study which will help us to better understand the disorder itself.
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