Short‐term exposure to enriched environment rescues chronic stress‐induced impaired hippocampal synaptic plasticity, anxiety, and memory deficits

Abstract

Exposure to prolonged stress results in structural and functional alterations in the hippocampus including reduced long-term potentiation (LTP), neurogenesis, spatial learning and working memory impairments, and enhanced anxiety-like behavior. On the other hand, enriched environment (EE) has beneficial effects on hippocampal structure and function, such as improved memory, increased hippocampal neurogenesis, and progressive synaptic plasticity. It is unclear whether exposure to short-term EE for 10 days can overcome restraint stress-induced cognitive deficits and impaired hippocampal plasticity. Consequently, the present study explored the beneficial effects of short-term EE on chronic stress-induced impaired LTP, working memory, and anxiety-like behavior. Male Wistar rats were subjected to chronic restraint stress (6 hr/day) over a period of 21 days, and then they were exposed to EE (6 hr/day) for 10 days. Restraint stress reduced hippocampal CA1-LTP, increased anxiety-like symptoms in elevated plus maze, and impaired working memory in T-maze task. Remarkably, EE facilitated hippocampal LTP, improved working memory performance, and completely overcame the effect of chronic stress on anxiety behavior. In conclusion, exposure to EE can bring out positive effects on synaptic plasticity in the hippocampus and thereby elicit its beneficial effects on cognitive functions. © 2016 Wiley Periodicals, Inc.

The ameliorating effect of exercise on long-term memory impairment and dendritic retraction via the mild activation of AMP-activated protein kinase in chronically stressed hippocampal CA1 neurons

“…A large body of evidence demonstrated chronic stress-induced neuronal remodeling in limbic structures such as the hippocampus 3 - 6 , 26 , 27 . Specifically, the diminished synaptic efficacy of hippocampal CA1 neurons was suggested to be related to abnormal structural plasticity which results in failure to consolidate long-term memory 12 , 13 . The postsynaptic architecture of excitatory synapses is regarded as an important component of connectivity between neurons, ultimately modulating neuronal excitability 13 , 28 .…”

Environmental enrichment modulates the response to chronic stress in zebrafish

“…Regarding behavioral effects, some studies in rats submitted to chronic stress have shown that EE improved working memory performance in the T-maze task, and prevented anxiety-like behavior in the elevated plus maze test (Bhagya et al, 2017). EE also prevented depression-like behavior in the sucrose preference test, and partially prevented the anxiogenic-like effect of chronic stress, attenuating the spatial learning difficulty and memory impairment in the radial arm maze in rodents (Shilpa et al, 2017).…”

Midlife stress alters memory and mood-related behaviors in old age: Role of locally activated glucocorticoids

“…In addition to impaired spatial memory, enhanced fear memory and impaired extinction, aged WT mice also showed increased anxiety and depressive-like behaviors 6 months after midlife stress, consistent with the persistent behavioral abnormalities associated with stress-related psychopathologies ( Finsterwald and Alberini, 2014 ). Whereas increased anxiety and depressive-like behaviors have been reported days after chronic stress in rats and mice ( Bhagya et al, 2017 ; Santana et al, 2015 ), few studies have examined affective behaviors months after stress. Increased anxiety-related behaviors have been reported in rats 3 months after predator stress ( Zoladz et al, 2015 ) but until now the persistence of depressive-like behaviors months after stress cessation has not been described.…”