Neurochemical Research

, Volume 33, Issue 9, pp 1651–1662 | Cite as

Self-Stimulation Rewarding Experience Restores Stress-Induced CA3 Dendritic Atrophy, Spatial Memory Deficits and Alterations in the Levels of Neurotransmitters in the Hippocampus

  • K. Ramkumar
  • B. N. Srikumar
  • B. S. Shankaranarayana Rao
  • T. R. Raju
Original Paper


Chronic restraint stress causes spatial learning and memory deficits, dendritic atrophy of the hippocampal pyramidal neurons and alterations in the levels of neurotransmitters in the hippocampus. In contrast, intracranial self-stimulation (ICSS) rewarding behavioral experience is known to increase dendritic arborization, spine and synaptic density, and increase neurotransmitter levels in the hippocampus. In addition, ICSS facilitates operant and spatial learning, and ameliorates fornix-lesion induced behavioral deficits. Although the effects of stress and ICSS are documented, it is not known whether ICSS following stress would ameliorate the stress-induced deficits. Accordingly, the present study was aimed to evaluate the role of ICSS on stress-induced changes in hippocampal morphology, neurochemistry, and behavioral performance in the T-maze. Experiments were conducted on adult male Wistar rats, which were randomly divided into four groups; normal control, stress (ST), self-stimulation (SS), and stress + self-stimulation (ST + SS). Stress group of rats were subjected to restraint stress for 6 h daily over 21 days, SS group animals were subjected to SS from ventral tegmental area for 10 days and ST + SS rats were subjected to restraint stress for 21 days followed by 10 days of SS. Interestingly, our results show that stress-induced behavioral deficits, dendritic atrophy, and decreased levels of neurotransmitters were completely reversed following 10 days of SS experience. We propose that SS rewarding behavioral experience ameliorates the stress-induced cognitive deficits by inducing structural and biochemical changes in the hippocampus.


Chronic restraint stress Biogenic amines Hippocampus Spatial learning Dendritic atrophy Acetylcholinesterase activity T-maze Rewarded alternation task 



This work was supported by research grants from Department of Science and Technology (DST), Government of India. We thank ADJ Titus for help in collating Golgi images.


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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • K. Ramkumar
    • 1
  • B. N. Srikumar
    • 1
  • B. S. Shankaranarayana Rao
    • 1
  • T. R. Raju
    • 1
  1. 1.Department of NeurophysiologyNational Institute of Mental Health and Neuro Sciences (NIMHANS)BangaloreIndia

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