Reduced expression of the "fast" calcium transporter PMCA2a during homeostatic plasticity.

In a model of homeostatic plasticity, hippocampal slice culture CA3 pyramidal neurons responded to excitatory synapse inactivity by enhancing glutamate release through an increased number of miniature excitatory post-synaptic currents, mEPSCs and excitatory pre-synaptic terminals. Also accompanying these changes was a specific reduction in the expression of a "fast" calcium transporter, the plasma membrane calcium ATPase, PMCA2a. This transporter normally influences glutamate release from excitatory terminals where it helps control calcium levels.

The cell adhesion molecule neuroplastin-65 inhibits hippocampal long-term potentiation via a mitogen-activated protein kinase p38-dependent reduction in surface expression of GluR1-containing glutamate receptors.

Neuroplastin-65 is a brain-specific, synapse-enriched member of the immunoglobulin (Ig) superfamily of cell adhesion molecules. Previous studies highlighted the importance of neuroplastin-65 for long-term potentiation (LTP), but the mechanism was unclear. Here, we show how neuroplastin-65 activation of mitogen-activated protein kinase p38 (p38MAPK) modified synapse strength by altering surface glutamate receptor expression.

Network stability through homeostatic scaling of excitatory and inhibitory synapses following inactivity in CA3 of rat organotypic hippocampal slice cultures.

Homeostatic plasticity is a phenomenon whereby synaptic strength is scaled in the context of the activity that the network receives. Here, we have analysed excitatory and inhibitory synapses in a model of homeostatic plasticity where rat organotypic hippocampal slice cultures were deprived of excitatory synaptic input by the NMDA and AMPA/KA glutamate receptor antagonists, AP5 and CNQX. We show that chronic excitatory synapse deprivation generates an excitable CA3 network where enhanced amplitude and frequency of spontaneous excitatory post-synaptic potentials were associated with increased glutamate receptor subunit expression and increased number and size of synapsin 1 and VGLUT1 positive puncta.

Expression of plasma membrane Ca2+ ATPase family members and associated synaptic proteins in acute and cultured organotypic hippocampal slices from rat.

Plasma membrane Ca2+ ATPases (PMCAs) are critical regulators of intracellular Ca2+ concentration ([Ca2+]i). Specific isoforms have also been demonstrated to interact and co-localise with members of the synapse-associated protein (SAP) family in hippocampal dendritic spines. Presently, only indirect evidence of changes in PMCA protein expression during postnatal development exists, therefore we chose to examine the postnatal developmental protein expression patterns of PMCAs 1-4 and the SAP proteins SAP102 and PSD95.

Comparison of neuroplastin and synaptic marker protein expression in acute and cultured organotypic hippocampal slices from rat.

Organotypic hippocampal slice cultures can be used to study hippocampal biochemistry and physiology over a chronic period on the days to weeks timescale. In order to validate the organotypic hippocampal slice culture for our ongoing studies of synaptic function, we have compared, using Western blotting, the levels of a number of synaptic proteins from in vitro organotypic hippocampal slice cultures with those from in vivo hippocampal slices prepared from age-matched controls. We chose to follow the developmental expression of the neuroplastin (np) family of immunoglobulin related cell adhesion molecules (CAMs), np65, a brain specific isoform highly expressed in hippocampal neurones and np55 a more widely expressed isoform and two synaptic marker proteins, synaptophysin, a pre-synaptic marker and post-synaptic density protein-95, PSD95, a post-synaptic marker.