Effects of chronic cocaine administration on spatial learning and hippocampal spine density in two genetically different strains of rats

Neurobiol Learn Mem. 2011 May;95(4):491-7. doi: 10.1016/j.nlm.2011.02.012. Epub 2011 Mar 1.


Lewis and Fischer-344 rats have been proposed as an addiction model because of their differences in addiction behaviour. It has been suggested that drug addiction is related to learning and memory processes and depends on individual genetic background. We have evaluated learning performance using the eight-arm radial maze (RAM) in Lewis and Fischer-344 adult rats undergoing a chronic treatment with cocaine. In order to study whether morphological alterations were involved in the possible changes in learning after chronic cocaine treatment, we counted the spine density in hippocampal CA1 neurons from animals after the RAM protocol. Our results showed that Fischer-344 rats significantly took more time to carry out test acquisition and made a greater number of errors than Lewis animals. Nevertheless, cocaine treatment did not induce changes in learning and memory processes in both strains of rats. These facts indicate that there are genetic differences in spatial learning and memory that are not modified by the chronic treatment with cocaine. Moreover, hippocampal spine density is cocaine-modulated in both strains of rats. In conclusion, cocaine induces similar changes in hippocampal neurons morphology that are not related to genetic differences in spatial learning in the RAM protocol used here.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Behavior, Addictive / genetics
  • CA1 Region, Hippocampal / cytology
  • CA1 Region, Hippocampal / drug effects*
  • Central Nervous System Stimulants / pharmacology*
  • Cocaine / pharmacology*
  • Cocaine-Related Disorders / genetics
  • Dendritic Spines / drug effects*
  • Disease Models, Animal
  • Male
  • Maze Learning / drug effects*
  • Neuronal Plasticity / drug effects
  • Rats
  • Rats, Inbred F344
  • Rats, Inbred Lew
  • Spatial Behavior / drug effects
  • Species Specificity
  • Time Factors


  • Central Nervous System Stimulants
  • Cocaine