Neuroscience 2005 Abstract
| Presentation Number: | 729.10 |
|---|---|
| Abstract Title: | Spermine differentially affects the activity of hippocampal interneurons in slices. |
| Authors: |
Inyushin, M. Y.*1
; Kucheryavykh, Y. V.1
; Burnashev, N.
; Laube, G.
; Veh, R. W.
; Gmiro, V.
; Eaton, M. J.1
; Skatchkov, S. N.1
1Univ. Central del Caribe, Bayamon, Puerto Rico |
| Primary Theme and Topics |
Neural Excitability, Synapses, and Glia: Cellular Mechanisms - Synaptic Transmission -- Modulation |
| Session: |
729. Synaptic Modulation: Atypical Compounds Poster |
| Presentation Time: | Tuesday, November 15, 2005 2:00 PM-3:00 PM |
| Location: | Washington Convention Center - Hall A-C, Board # J4 |
| Keywords: | POLYAMINE, CA1, POTASSIUM, GLIA |
The polyamine, spermine (SPM) is an endogenous regulator of neurotransmission (Nature 401(1999)594; J. Neurophysiol. 93(2005)2634). SPM is mainly stored in glia, not in neurons (Glia 19(1997)171) and SPM levels in astrocytes vary with the functional state of glia (SFN 2004 No. 284.7). The purpose of the present study was to determine the effects of exogenous SPM and other treatments that release SPM from glia in comparison to the effect of the GluR2 lacking AMPA receptor antagonist IEM-1460 on the electrical activity of hippocampal interneurons. Solutions were applied by bath perfusion so that all cells in the slice were exposed. We found populations of interneurons in both s. oriens and s. radiatum that responded to exogenous SPM (200 µM) with hyperpolarization accompanied by a decreased firing rate (32%), with depolarization accompanied by increase in firing frequency (16%) or with no effect (52%). IEM-1460 (10 µM) always produced the same effect as SPM. Furthermore, we found that glial specific treatments that depolarize glia but do not significantly change the electrical properties of isolated neurons (elevated [K+]o from 2.5 to 8 mM, 10 µM Ba2+), changed the firing frequency and membrane potential of neurons in brain slices much like SPM. As SPM is localized in astrocytes and released upon depolarization, we suggest that the effects of [K+]o and Ba2+ are due to release of SPM from astrocytes. We conclude that the inhibitory effects of SPM are due to direct blockade of GluR2 lacking AMPA receptors on interneurons, whereas the excitatory effects may be due to either activation of GluR6-containing kainate receptors on interneurons or disinhibition of the interneuron through the neuronal connectivity. These data support our previous findings in non-enzymatically isolated neurons.
Supported by RCMI G12-RR03035, MBRS S06GM50695, NINDS and NCRR U54-NS39408, RFBR#04-04-49141 and DFG Ve-187/1-3
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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