Donohue, H.S.; Gabbott, P.L.A.; Davies, H.A.; Cordero, M.I.; Sandi, C.; Rodriguez, J.J.; Colyer, F.M.; Peddie, C.J.; Medvedev, N.; Popov, V.I. and Stewart, M.G.
Stress increases 'Axo-spinous' post-synaptic density size in CA1 stratum lacunosum-moleculare: a three-dimensional ultrastructural study [poster presentation].
In: British Neuroscience Association (BNA) Meeting, 5-8 April 2005, Brighton, UK.
Stress alters the synaptic connectivity of hippocampal neurones (Sandi et al., Euro. J. Neurosci. 17: 2446-2476). Stereological studies in our laboratory indicate that chronic restraint stress (CRS; 6h/day, 21days) significantly increases the size of the post-synaptic density (PSD) membranes of asymmetric axo-spinous synapses in dorsal anterior CA1 stratum lacunosum-moleculare. No change occured in the absolute number of these synapses between groups.
To further characterise these stress-associated synaptic alterations, 3-D reconstructions of asymmetric axo-spinous PSD membranes were performed using electron-microscope images obtained from serial ultrathin sections. Thirty synapses per animal were reconstructed (4 animals per group). The associated dendritic spines of the identified synapses were also reconstructed in 3-D. Our preliminary findings indicate a significant increase in PSD membrane surface area of asymmetric axo-spinous synapses following CRS (+36%; p=0.026) and a highly significant increase in PSD membrane volume (+77%; p=0.003). No significant alterations were detected in the surface area or volume of reconstructed dendritic spines.
These results verify our earlier stereological findings that CRS significantly increases the size of asymmetric axo-spinous synaptic junctions in dorsal-anterior CA1 stratum lacunosum-moleculare. This reinforces our previous conclusion that a structural remodelling of asymmetric ‘excitatory’ axo-spinous synapses occurs in this region of CA1 hippocampus following CRS.
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