Evidence for altered Fragile-X mental retardation protein expression in response to behavioral stimulation.
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.
Irwin
S A
SA
Beckman Institute, University of Illinois, Urbana 61801, USA.
Swain
R A
RA
Christmon
C A
CA
Chakravarti
A
A
Weiler
I J
IJ
Greenough
W T
WT
D000818:Animals; D051860:Fragile X Messenger Ribonucleoprotein 1; D005786:Gene Expression Regulation / Q000502:physiology; D008297:Male; D009044:Motor Cortex / Q000033:anatomy & histology*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009473:Neuronal Plasticity / Q000235:genetics*; D016601:RNA-Binding Proteins; D051381:Rats; D020318:Rats, Long-Evans; D012931:Social Environment; D009435:Synaptic Transmission / Q000235:genetics*; D014793:Visual Cortex / Q000033:anatomy & histology*
D051860:Fragile X Messenger Ribonucleoprotein 1; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; C497685:Fmr1 protein, rat