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Characterization of the Spontaneous Synaptic Activity of Amacrine Cells in the Mouse Retina
Max-Planck-Institut für Hirnforschung, Neuroanatomische Abteilung, D-60528 Frankfurt am Main, Germany Frech, Moritz J., Jorge Pérez-León, Heinz Wässle, and Kurt H. Backus. Characterization of the Spontaneous Synaptic Activity of Amacrine Cells in the Mouse Retina. J. Neurophysiol. 86: 1632-1643, 200...
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Published in: | Journal of neurophysiology 2001-10, Vol.86 (4), p.1632-1643 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
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Summary: | Max-Planck-Institut für Hirnforschung, Neuroanatomische
Abteilung, D-60528 Frankfurt am Main, Germany
Frech, Moritz J.,
Jorge Pérez-León,
Heinz Wässle, and
Kurt H. Backus.
Characterization of the Spontaneous Synaptic Activity of Amacrine
Cells in the Mouse Retina. J. Neurophysiol. 86: 1632-1643, 2001. Amacrine cells are a heterogeneous class
of interneurons that modulate the transfer of the light signals through
the retina. In addition to ionotropic glutamate receptors, amacrine
cells express two types of inhibitory receptors,
GABA A receptors (GABA A Rs) and glycine receptors (GlyRs). To characterize the functional contribution of these different receptors, spontaneous postsynaptic currents (sPSCs) were recorded with the whole cell
configuration of the patch-clamp technique in acutely isolated slices
of the adult mouse retina. All amacrine cells investigated
( n = 47) showed spontaneous synaptic activity. In six
amacrine cells, spontaneous excitatory postsynaptic currents could be
identified by their sensitivity to kynurenic acid. They were
characterized by small amplitudes [mean: 13.7 ± 1.5 (SE) pA] and rapid decay kinetics (mean : 1.35 ± 0.16 ms). In contrast, the reversal potential of sPSCs characterized by slow
decay kinetics (amplitude-weighted time constant,
w , >4 ms) was dependent on the intracellular
Cl concentration ( n = 7),
indicating that they were spontaneous inhibitory postsynaptic currents
(sIPSCs). In 14 of 34 amacrine cells sIPSCs were blocked by bicuculline
(10 µM), indicating that they were mediated by
GABA A Rs. Only four amacrine cells showed glycinergic sIPSCs that were inhibited by strychnine (1 µM). In one
amacrine cell, sIPSCs mediated by GABA A Rs and
GlyRs were found simultaneously. GABAergic sIPSCs could be
subdivided into one group best fit by a monoexponential decay function
and another biexponentially decaying group. The mean amplitude of
GABAergic sIPSCs ( 42.1 ± 5.8 pA) was not significantly
different from that of glycinergic sIPSCs ( 28.0 ± 8.5 pA).
However, GlyRs (mean T10/90: 2.4 ± 0.08 ms) activated significantly
slower than GABA A Rs (mean T10/90: 1.2 ± 0.03 ms). In addition, the decay kinetics of monoexponentially decaying
GABA A Rs (mean w :
20.3 ± 0.50), biexponentially decaying GABA A Rs (mean w :
30.7 ± 0.95), and GlyRs (mean w = 25.3 ± 1.94) were significantly different. These differences in
the activation and decay kinetics of sIPSCs indicate that amacrine
cells of the mouse retina express at least three ty |
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ISSN: | 0022-3077 1522-1598 |
DOI: | 10.1152/jn.2001.86.4.1632 |