#sfn14 – As time goes by: The gradual impact of chronic stress on rodent hippocampal structure and function

I won’t be there but go see our poster anyway – presented by Mostafizur Rahmen.

Program#/Poster#: 745.05/SS30
Presentation Title: As time goes by: The gradual impact of chronic stress on rodent hippocampal structure and function
Location: WCC Hall A-C
Presentation time: Wednesday, Nov 19, 2014, 8:00 AM -12:00 PM
Presenter at Poster: Wed, Nov. 19, 2014, 8:00 AM – 9:00 AM
Topic: ++F.02.g. Executive function: Models of Disorders
1Natl. Ctr. for Biol. Sci., Bangalore, India; 2Trinity Col. Inst. of Neuroscience, Trinity Col. Dublin, Dublin, Ireland
Abstract: Accumulating evidence from neuroimaging and clinical studies show that exposure to prolonged and severe stress has detrimental effects on hippocampal structure and function. Animal models of chronic stress have been used to probe the underlying causes of stress-induced damage at multiple levels of neural. A majority of these studies, however, relied primarily on postmortem analysis at the end of repeated stress. Relatively little is known about gradual changes in hippocampal structure, and its behavioral consequences, during the course of repeated stress in the same animal. Here, we examined how chronic immobilization stress (2 h/day for 10 days) affected hippocampal volume and hippocampal-dependent spatial learning in adult male Wistar rats. Specifically, we analyzed if and how changes in hippocampal volume predict impairment of spatial memory in the same animal during and after the 10-day stress protocol. Using a 7T MRI scanner, we quantified a gradual decrease in hippocampal volume over the course of the 10-day chronic stress. A significant decrease in volume was seen as early as the 3rd day of stress. Further, loss of left hippocampal volume was greater that the right hippocampus. The same rats, when tested on the Morris Water Maze task during days 4, 5, & 6 exhibited only a mild deficit in the retention, but not acquisition, of spatial memory for the hidden platform. However, after the end of chronic stress, the same animals showed a significant deficit in the Object Displacement Task. These behavioral results point to a gradual build-up in spatial memory deficits over the course of chronic stress. Consistent with earlier human studies, the reduction in hippocampal volume was strongly correlated with the spatial memory deficit seen at the end of chronic stress. Strikingly, the decrease in hippocampal volume even on day 3 was correlated with the eventual spatial memory deficit seen after the end of stress. This suggests that animals that were worst affected both in terms of memory deficits and hippocampal atrophy at the end of chronic stress, show relatively early signs of stress-induced impairment and continue on a trajectory of steady decline as the stress is repeated. Taken together, these findings suggest that not only is loss of hippocampal volume linked to memory deficits caused by repeated stress, but it may also serve as an early indicator for the eventual cognitive impairment seen in stress-related psychiatric disorders.
Disclosures:  M. Rahman: None. C. Kerskens: None. C.K. Callaghan: None. S. Chattarji: None. S.M. O’Mara: None.
Keyword (s): STRESS
Support: Science Foundation Ireland (SFI), Short Term Travel Fellowship


Author: Shane O'Mara

Neuroscientist, Psychologist, Writer

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