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Title: Characterization of changes in synaptic strength in the CA1 region of the hippocampus by the analysis of miniature synaptic currents
Author: Baxter, Andrew William
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2005
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To mimic the LTP-like postsynaptic calcium concentration change, that occurs following NMDA receptor activation, we have used a depolarizing voltage pulse (VP) stimulating protocol to increase intracellular calcium levels via L-type calcium channels. Characterization of VP stimulation was done by whole-cell patch-clamp recordings from CA1 pyramidal neurones in organiotypic hippocampal slices. Culturing these slices maintains the hippocampal architecture, but results in an increase in the number of synaptic sites. The increase in synapse number, allows for the greater detection of mEPSCs allowing for the functional changes brought about by the VP stimulus to be better characterized. Following the VP stimulus there is a mean doubling of the amplitudes of the mEPSCs with a small non significant increase in mEPSC frequency. To assess whether the increase in amplitude of mEPSCs requires the insertion of AMPA receptors into postsynaptic sites we inhibited the actions of several proteins involved in intracellular membrane fusion events. In these experiments inhibitors were included in the patch-pipette to restrict their actions to the postsynaptic cell. We observed that both N-ethylmaleimide and botulinum toxin A inhibited the NSF dependent delivery of AMPA receptors to synapses, by blocking the induction of VP potentiation. This finding was supported by a Pep2m blockade of the induction of VP potentiation. Pep2m, a peptide that blocks the NSF binding site on the C-terminus of the GluR2 AMPA receptor subunit also blocked VP potential, while a scrambled version of this peptide, Pep4c failed to block potentiation. Further experiments using Pep-AVKI characterized a second delivery system, dependent upon PDZ domains, and suggested the possible involvement of PICK-1 in VP potentiation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available