Neurobiology of Disease (Jan 2006)

Hippocampal synaptic plasticity is impaired in the Mecp2-null mouse model of Rett syndrome

  • Yukiko Asaka,
  • Denis G.M. Jugloff,
  • Liang Zhang,
  • James H. Eubanks,
  • Reiko Maki Fitzsimonds

Journal volume & issue
Vol. 21, no. 1
pp. 217 – 227

Abstract

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Rett syndrome is an X-linked neurodevelopmental disorder caused by mutations in the gene encoding the transcriptional repressor methyl-CpG-binding protein 2 (MeCP2). Here we demonstrate that the Mecp2-null mouse model of Rett syndrome shows an age-dependent impairment in hippocampal CA1 long-term potentiation induced by tetanic or theta-burst stimulation. Long-term depression induced by repetitive low-frequency stimulation is also absent in behaviorally symptomatic Mecp2-null mice. Immunoblot analyses from behaviorally symptomatic Mecp2-null mice reveal altered expression of N-methyl-d-aspartate receptor subunits NR2A and NR2B. Presynaptic function is also affected, as demonstrated by a significant reduction in paired-pulse facilitation. Interestingly, the properties of basal neurotransmission are normal in the Mecp2-null mice, consistent with our observations that the levels of expression of synaptic and cytoskeletal proteins, including glutamate receptor subunits GluR1 and GluR2, PSD95, synaptophysin-1, synaptobrevin-2, synaptotagmin-1, MAP2, βIII-tubulin and NF200, are not significantly altered. Together, these data provide the first evidence that the loss of Mecp2 expression is accompanied by age-dependent alterations in excitatory synaptic plasticity that are likely to contribute to the cognitive and functional deficits underlying Rett syndrome.

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