تأثير بتا استرادیول بر نسبتBcl2/BAX نورونهاي هیپوکمپ موشهاي صحرايي متعاقب القاي فشار روانی پس از سانحه (PTSD)

Abstract

Introduction: Post-traumatic stress disorder (PTSD) is an anxiety disorder, that can occur in people who have experienced or witnessed a natural disaster, serious accident or other life-threatening events. It's most important characteristics are memory disorders and hippocampus is one of the essential structure in this relation. Traumatic events cause apoptosis and alter the expression of neurotrophic factors in hippocampus. Therefore, the aim of this study was the examination of the fear memory and evaluation the effects of multiple β-Estradiol injections on behavioral responses in the rat hippocampus, after induction of PTSD. Moreover, we evaluated, the biochemical and histological mechanisms of β-Estradiol on hippocampus. Methods: We used single prolonged stress (SPS), for PTSD induction. One day after SPS, rats received electrical foot shock within shock chamber. To test the conditioned fear responses one week later, rats were placed back in the chamber without any shock, and freezing behavior was defined. Another fear test was done 4 days after the first test. Animals received multiple subcutaneous injections of β-estradiol (45µg/kg) or sesame oil, immediately after shock and in these 7 days, between shock and test. Bcl-2 and BAX were detected by immunohistochemistry. Results: Main findings of the present study are: Exaggerated fear response was seen in PTSD group as compared with control group. Moreover, Β-estradiol administration reduced behavioral responses, caused by PTSD induction. SPS decreased the Bcl2/BAX ratio and apoptosis induced by SPS in hippocampus. This effects reversed by β-estradiol injections. Conclusion: β-estradiol could be useful for treating the memory disorders in PTSD.