Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

Long-term potentiation (LTP) of synaptic efficacy was examined in interneurons located in the stratum radiatum of the hippocampal CA1 subfield. Neurons were recorded using Differential Interference Contrast (DIC) optics and whole-cell patch-clamp techniques. All neurons were labelled with 0.3-0.5% biocytin for post-experimental histological identification. Application of tetanic stimulation at 200 Hz was found to reliably produce LTP when administered in slices maintained at 34 degrees Celcius (75 + 29%; n=12), but not when administered to slices maintained at 23 degrees Celcius (18 + 9%; n=13). The LTP was like that observed in hippocampal CA1 pyramidal cells in that it was dependent upon the activation of n-methyl-D-aspartate (NMDA) receptors and required post-synaptic Ca2+-influx for it's genesis. The induction of LTP in S.R. interneurons also appeared to be activity-dependent, possibly requiring Na+-dependent post-synaptic action potentials, as inclusion of QX-314 in the internal pipette solution prevented the induction of LTP. LTP similar in magnitude was also obtained in response to tetanic stimuli administered at 100 Hz. While LTP was readily obtained in these cells, homosynaptic LTD was not readily induced with low-frequency stimuli (3 Hz). These results indicate that hippocampal stratum radiatum interneurons are capable of exhibiting long-lasting changes in synaptic efficacy. The capacity to exhibit such alterations greatly enhances the number of possible interactions hippocampal interneurons can form with other cells.

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Poster Number PAchristie0690
Keywords: ltp, calcium, nmda, ltd, whole-cell