[Abstract Title]. - Society for Neuroscience

immunohistochemisty revealed that the up-regulated expression of NRP-1 and VEGF occurred
in the entorhinally denervated dentate out molecular layer and hippocampal stratum lacunosummolecular
layer, and reactive astrocytes co-expressed both of them. Meanwhile NRP-1 was also
expressed by the neuritis in the denervated area and the granule cells and its processes, which
most likely belong to sprouting axons and/or regrowing dendrites. Double labeling of NRP-1 and
GAP-43 also demonstrated the clustered expression of NRP-1 by regenerated axonal terminals
surrounding the VEGF positive reactive astrocytes. Our data indicates that spatiotemporal shift
of a balance from Sema3A/NRP-1 to VEGF/NRP-1 facilitates the layer-specific neurite
outgrowth and circuits reorganization in the deafferented hippocampus and the crosstalk between
neurons and reactive astrocytes may be involved in the plasticity events of the adult brain after
injury.
Disclosures: W. Wang, None; C. Zhou, None.
Poster
241. Glial Neuronal Interactions
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 241.23/H5
Topic: B.11.a. Synapses
Support: NSERC
Title: Role of astrocyte FMRP on synapse development in Fragile X Syndrome
Authors: *S. STEAD, M. NATHWANI, U. SHETH, L. C. DOERING;
Pathology & Mol. Med., McMaster Univ., Hamilton, ON, Canada
Abstract: Fragile X Syndrome (FXS) is the most common cause of inherited mental impairment
that affects approximately 1 in 2000 males and 1 in 4000 females. FXS is caused by a
trinucleotide repeat expansion in the FMR1 gene, resulting in gene silencing and lack of the
protein product termed Fragile X Mental Retardation Protein (FMRP). Abnormal synapse
morphology and function may contribute to the clinical features of FXS.
We recently reported the expression of FMRP in cells of the astrocyte lineage (Pacey and
Doering, 2007). Glial cells are known to play integral roles in the development and maintenance
of synapses in the CNS. We therefore examined if neuronal process formation and synapse
development are affected by FMRP in astrocytes. To address this question we utilized a coculture
system of astrocytes and neurons as described by Kaech & Banker (2006), with
modifications. Hippocampal neurons (E16-E17) and cortical astrocytes (P0-P1) were
independently isolated from FMR1 knock out or wild type mice to establish the combinations of