Enriched environment modulates behavior, myelination and augments molecules governing the plasticity in the forebrain region of rats exposed to chronic immobilization stress

  • Gangadharan Thamizhoviya
  • Arambakkam Janardhanam Vanisree
Original Article


Recently, several reports on chronic stress have shown that prolonged exposure to stress contributes to psychological and neurological complications. However, the impact of stress-induced alterations in myelination remains to be unexplored. Therefore, in the current study, the rats were subjected to immobilization stress (IS) followed by enriched environment (EE) and the behavioral, neurochemical changes pertaining to neuronal survival pathway, in addition, to the ultrastructural changes in myelin in forebrain (FB) region of rats were analyzed. Immobilization stress-exposed rats (4 h/day IS, for 28 days) exhibited increased anhedonia, anxiety, immobility, and reduced social interaction, which could be reflected in increased levels of corticosterone. In contrast, exposure to EE (4 h IS+2 h EE/day, for 28 days) was found to minimize anhedonic state, supress the depressive-like features, enhance social interaction and also reduce the levels of corticosterone. The ultrastructural changes in the FB region of the brain revealed that IS group showed enhanced g-ratio indicating decreased myelin thickness, while EE group exhibited reduced g-ratio manifesting increased myelination. Further, the study revealed that IS exposed group showed decreased levels of NGF, TrkA, PI3K, AKT, ERK, CREB, and MBP in FB regions whereas EE group could preserve normal protein and mRNA levels of these neuronal survival molecules. The results from this study suggest that EE exerts a positive impact by improving myelination in rats exposed to chronic immobilization stress.


Myelination Corticosterone Neurotrophic growth factor Myelin basic protein Enriched environment Immobilization stress Behavioral plasticity 



The authors thank the University Grants Commission-Special Assistance Programme, New Delhi, India, for the necessary financial support in the form of Fellowship.

Compliance with ethical standards

Disclosure statement

The authors indicate that there is no potential conflict of interest in this study.


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© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of BiochemistryUniversity of MadrasChennaiIndia

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