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Corelease of two functionally opposite neurotransmitters by retinal amacrine cells: Experimental evidence and functional significance
Author(s) -
Duarte Carlos B.,
Santos Paulo F.,
Carvalho Arsélio P.
Publication year - 1999
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/(sici)1097-4547(19991115)58:4<475::aid-jnr1>3.0.co;2-o
Subject(s) - neurotransmitter , neuroscience , postsynaptic potential , cholinergic , acetylcholine , amacrine cell , retinal , depolarization , biology , retinal waves , retina , chemistry , biophysics , microbiology and biotechnology , receptor , endocrinology , biochemistry , central nervous system , retinal ganglion cell , intrinsically photosensitive retinal ganglion cells
The Dale's law postulates that a neuron releases the same neurotransmitter from all its branches. In the case of mulitple neurotransmitters it would require all transmitters to be released from all branches. The retinal cholinergic amacrine cells contain and release γ‐aminobutyric (GABA) and, therefore, if GABA and acetylcholine (ACh) are released at the same sites, this could mean that amacrine cells simultaneously excite and inhibit postsynaptic cells. Conversely, if the two neurotransmitters are released at different synapses, or if their release is regulated in a distinct manner, they may play different physiological roles. Recent studies carried out in cultured cholinergic amacrine‐like neurons showed that Ca 2+ ‐dependent release of ACh and GABA have a different sensitivity to membrane depolarization, to the effect of blockers of voltage gated Ca 2+ channels (VGCC) and to the effect of presynaptic A 1 adenosine receptors. Therefore, it is proposed that in retinal amacrine cells the Ca 2+ ‐dependent release of ACh and GABA occurs at distinct cellular locations. The possible nature of these release sites and the physiological significance of this model are discussed in this review.J. Neurosci. Res. 58: 475–479, 1999. © 1999 Wiley‐Liss, Inc.