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Titolo:
HETEROSYNAPTIC SUPPRESSION OF DEVELOPING NEUROMUSCULAR SYNAPSES IN CULTURE
Autore:
LO YJ; POO MM;
Indirizzi:
COLUMBIA UNIV,DEPT BIOL SCI NEW YORK NY 10027 COLUMBIA UNIV,DEPT BIOL SCI NEW YORK NY 10027
Titolo Testata:
The Journal of neuroscience
fascicolo: 8, volume: 14, anno: 1994,
pagine: 4684 - 4693
SICI:
0270-6474(1994)14:8<4684:HSODNS>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
NERVE-MUSCLE INTERACTIONS; LONG-TERM POTENTIATION; XENOPUS CELL-CULTURE; LUMBRICAL MUSCLE; ACETYLCHOLINE; ELIMINATION; MECHANISMS; JUNCTION; INVITRO; RELEASE;
Keywords:
SYNAPTIC COMPETITION; SYNAPTOGENESIS; SYNAPTIC PLASTICITY; NEUROMUSCULAR JUNCTION; CELL CULTURE; XENOPUS LAEVIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
27
Recensione:
Indirizzi per estratti:
Citazione:
Y.J. Lo e M.M. Poo, "HETEROSYNAPTIC SUPPRESSION OF DEVELOPING NEUROMUSCULAR SYNAPSES IN CULTURE", The Journal of neuroscience, 14(8), 1994, pp. 4684-4693

Abstract

Activity-dependent competition between two spinal neurons coinnverating an embryonic myocyte was studied in Xenopus cell culture. We have characterized in detail the phenomenon of heterosynaptic suppression bywhich tetanic stimulation of one neuron results in functional suppression of the synapse made by the untetanized neuron (Lo and Poo, 1991). Fluorescence labeling of the neurons using two different fluorophoresrevealed that the coinnervating nerve terminals on the spherical myocyte were in close proximity. Heterosynaptic suppression could be induced when the postsynaptic cell was held under either current-clamp or voltage-cramp conditions during the tetanic stimulation. This finding, together with the observation that repetitive postsynaptic depolarization of the myocyte by direct current injection was much less effectivein inducing synaptic depression, suggests that postsynaptic ACh receptor activation plays a dominant role in the induction of heterosynaptic suppression. The heterosynaptic suppression appears to be mediated by a rise of Ca2+ levels in the postsynaptic cell, since it was not observed when the cytosolic Ca2+ concentration of the myocyte was buffered at a low level with intracellular loading of a Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N, N, N', N'-tetra-acetic acid (BAPTA). The dependence of heterosynaptic suppression on the pattern of tetanic stimulation was also studied. At a stimulation frequency of 2 Hz, detectable heterosynaptic suppression could be induced after 20 repetitive stimuli were applied to one of the presynaptic neurons and the suppressionwas more effective with increasing number of stimuli. Over the range of 0.5-5 Hz, the extent of suppression was independent of the frequency of tetanic stimulation and, in some cells, detectable suppression could be induced at a frequency as low as 0.05 Hz. Except for a few cases, heterosynaptic suppression was found to last for as long as the recording was made after tetanus (up to 1 hr). The fact that the mean amplitude of spontaneous synaptic currents remained the same before and after the suppression while the evoked synaptic currents exhibited higher fluctuation after suppression suggests that the observed synaptic suppression involves a reduction of evoked ACh release from the nerve terminal, although postsynaptic changes have not been excluded. Finally, we found that spontaneous synaptic activity may also contribute in part to the synaptic competition between coinnervating nerve terminals. Taken together, these findings provide a quantitative basis for further understanding of activity-dependent competition between developing neuromuscular synapses.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/04/20 alle ore 23:01:46