Neurotrophin-4 couples to locally modulated ACh release at the end of neuromuscular synapse maturation.
We use immunocytochemistry to show that neurotrophin-4 (NT-4) and its receptor proteins (p75(NTR) and tropomyosin-related tyrosine kinase B) are present in neonatal neuromuscular junctions (NMJ) colocalized with several synaptic markers. NT-4 incubation (1h, in the range 2-12 nM) does not change the size of the endplate potential between P6 and P45. However, extended exposure (3h) to a relatively low dose of NT-4 (2 nM) potentiates ACh release (approx. 70%) in adult but not in neonatal muscles. The present results suggest that the developmental mechanism of axonal competition and neonatal elimination of redundant synapses cannot be modulated by added NT-4. However, this neurotrophin was able to modulate synaptic transmission locally in the adult NMJ.
Garcia
N
N
Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Carrer Sant Llorenç 21, 43201-Reus, Spain. ngs@fmcs.urv.es
Santafe
M M
MM
Tomas
M
M
Lanuza
M A
MA
Besalduch
N
N
Tomas
J
J
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D051379:Mice; D009414:Nerve Growth Factors / Q000378:metabolism* / Q000494:pharmacology; D009469:Neuromuscular Junction / Q000254:growth & development / Q000502:physiology*; D009435:Synaptic Transmission
D009414:Nerve Growth Factors; D000109:Acetylcholine; C073922:neurotrophin 4