Elastic eletron scattering from the DNA bases: cytosie and thymine

XXVII International Conference on Photonic, Electronic and Atomic Collisions, Belfast, Northern Ireland, UK, 27 July - 2 August 2011Peer Reviewe

Stress-induced changes in synaptic morphology in rat CA1 hippocampus [poster presentation]

[Poster]: Ultrastructural studies in our laboratory have demonstrated that restraint stress significantly reduces axospinous synaptic density in the CA3 subfield of the rat hippocampus (Sandi et al. Euro. J. Neurosci. 17: 2446-2476). Because the CA1 subfield receives direct innervation from CA3 and is the major output area of the hippocampus, we examined the effects of restraint stress upon synaptic parameters in this strategic region. An unbiased stereological approach was used to compare numerical asymmetrical synaptic densities (Nv) and post-synaptic membrane lengths, between control and stress (restraint stress; 6h/day for 21 days started at c. 13wks of age) groups in CA1 hippocampus of rats (n=3, per experimental group). Measurements were taken throughout the stratum radiatum (StRad) and lacunosum moleculare (LacMol). Our data show that no statistically significant changes occur in Nv or post synaptic membrane length within the StRad of CA1. However, further statistical analysis (Student’s two-tailed t-test) reveal a significant increase in the lengths of individual post-synaptic membranes in the LacMol of CA1 (control group mean = 252.4nm; stress group mean = 355.2nm; p=0.027). These results indicate a stress-induced remodelling of synaptic connectivity in LacMol of CA1 that may underlie neurobiological mechanisms related to stress

Stress increases 'Axo-spinous' post-synaptic density size in CA1 stratum lacunosum-moleculare: a three-dimensional ultrastructural study [poster presentation]

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