Evidence for altered Fragile-X mental retardation protein expression in response to behavioral stimulation

Neurobiol Learn Mem. 2000 Jan;73(1):87-93. doi: 10.1006/nlme.1999.3914.


The Fragile-X mental retardation protein, the protein absent in Fragile-X syndrome, is synthesized near synapses upon neurotransmitter activation. Humans and mice lacking this protein exhibit abnormal dendritic spine lengths and numbers. Here we investigated Fragile-X protein levels in animals exposed to behavioral paradigms that induce neuronal morphological change. Fragile-X protein immunoreactivity was examined in visual cortices of rats reared in a complex environment for 10 or 20 days, motor cortices of rats trained on motor-skill tasks for 3 or 7 days, and either visual or motor cortices of inactive controls. Rats exposed to a complex environment for 20 days or trained for 7 days on motor-skill tasks exhibited increased Fragile-X protein immunoreactivity in visual or motor cortices, respectively. These results provide the first evidence for a behaviorally induced alteration of Fragile-X protein expression and are compatible with previous findings suggesting synaptic regulation of its expression. These results also strengthen the association of Fragile-X mental retardation protein expression with the alteration of synaptic structure.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Fragile X Mental Retardation Protein
  • Gene Expression Regulation / physiology
  • Male
  • Motor Cortex / anatomy & histology*
  • Nerve Tissue Proteins / genetics*
  • Neuronal Plasticity / genetics*
  • RNA-Binding Proteins*
  • Rats
  • Rats, Long-Evans
  • Social Environment*
  • Synaptic Transmission / genetics*
  • Visual Cortex / anatomy & histology*


  • Fmr1 protein, rat
  • Nerve Tissue Proteins
  • RNA-Binding Proteins
  • Fragile X Mental Retardation Protein