Reduced number of functional glutamatergic synapses in hippocampal neurons overexpressing full-length TrkB receptors.
J Neurosci Res
; 66(3): 327-36, 2001 Nov 01.
Article
en En
| MEDLINE
| ID: mdl-11746350
Brain-derived neurotrophic factor (BDNF) acutely modulates the efficacy of central glutamatergic synapses via activation of the receptor tyrosine kinase TrkB. On a longer time scale, recent evidence suggests an additional role of TrkB signaling in the formation of excitatory synaptic connections. Here, we have overexpressed full-length TrkB receptors (fl-TrkB) in hippocampal neurons, to investigate the contribution of BDNF signaling to the maturation of glutamatergic synapses. Using patch clamp recordings, we show a three-fold reduction in glutamatergic excitatory autaptic and synaptic current amplitudes in neurons overexpressing fl-TrkB, and application of saturating concentrations of BDNF and NT-4/5 completely reverses this effect. Compatible with these overexpression data, in untransfected neurons, scavenging of endogenous BDNF and NT-4/5 by TrkB-IgGs reduces excitatory autaptic current (EAC) amplitudes. By overexpression of truncated TrkB receptors (TrkB.T1, TrkB.T2) and a chimeric receptor containing only the intracellular domain of fl-TrkB, we show that intra- and extracellular domains of fl-TrkB are necessary to observe the EAC reduction. Labeling of presynaptic terminals with FM 4-64 revealed, that the reduced EAC amplitudes in fl-TrkB overexpressing neurons are accompanied by a two-fold reduction in synapse number. These results suggest, that ligand-independent signaling through fl-TrkB receptors can decrease glutamatergic synaptic strength, if sufficient amounts of BDNF or NT-4/5 are not available.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Sinapsis
/
Regulación hacia Abajo
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Ácido Glutámico
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Factor Neurotrófico Derivado del Encéfalo
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Receptor trkB
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Hipocampo
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Neuronas
Idioma:
En
Revista:
J Neurosci Res
Año:
2001
Tipo del documento:
Article
País de afiliación:
Alemania
Pais de publicación:
Estados Unidos