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Abstract:   (37 Views)
Introduction: Psychological stresses influent brain functions such as learning and memory. Environmental factors like types and durations of stress affect brain responsiveness. This study investigated the effects of two sub chronic social and isolation stresses on learning, memory, adrenal glands weight and corticosterone (CORT) levels in hippocampus and frontal cortex.
Methods: Eighteen male rats were randomly allocated into three experimental groups: control (Co), social stress (SS) and isolation stress (IS) groups. Rats were under stresses for 7 days. Learning and memory were assessed by the passive avoidance test at 1, 3, 5 and 7 days after foot shock.
Results: Results revealed that the latencies of days 1, 3 and 5 were significantly (P<0.05, P<0.01 and P<0.01, respectively) lower in IS group than Co group in similar trials. The latency of day7 showed significant (P<0.001) decreases in SS and IS groups compared to Co group. The adrenal glands weight showed significant enhancements (P<0.05 and P<0.01, respectively) in SS and IS groups compared to Co group. There was a significant (P<0.05) enhancement in the CORT levels of hippocampus, but not frontal cortex in IS group. Also, adrenal glands weight significantly (P<0.05) increased in IS group compared to SS group.
Conclusion: It was concluded that learning and memory were impaired in both psychological stresses, particularly memory deficits happened in isolation stress earlier than social stress. Also, isolation stress affected CORT level in hippocampus more than frontal cortex. Therefore, sub chronic isolation stress severely deteriorated brain functions compared with social stress.
     
Types of Manuscript: Original Research | Subject: Learning and memory