Y. Akaneya et al., BRAIN-DERIVED NEUROTROPHIC FACTOR ENHANCES LONG-TERM POTENTIATION IN RAT VISUAL-CORTEX, The Journal of neuroscience, 17(17), 1997, pp. 6707-6716
Brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), me
mbers of the nerve growth factor (NGF) gene family, have been suggeste
d to play a role in experience-dependent modification of neural networ
ks in the developing nervous system. In this study we addressed the qu
estion of whether these neurotrophins are involved in long-term potent
iation (LTP) in developing visual cortex. We recorded layer II/III fie
ld potentials and whole-cell currents evoked by test stimulation of la
yer IV at 0.1 Hz in visual cortical slices prepared from young rats (p
ost natal day 15-25) and observed effects of BDNF, NT-3, and NGF on th
ese responses. Then we analyzed the effects of these neurotrophins on
LTP induced by tetanic (Theta-burst type) stimulation of layer IV. We
found that BDNF at 200 ng/ml potentiated field potentials and EPSCs in
most cases and that this potentiation lasted after cessation of the B
DNF application. At the concentration of 20 ng/ml, BDNF did not show s
uch an effect, but it enhanced the magnitude of expressed LTP. On the
other hand, NT-3 and NGF had none of these effects. Immunohistochemica
l staining of slices with antibody against BDNF showed that exogenous
BDNF penetrated into the whole slice within similar to 5 min of its ap
plication. The actions of BDNF were blocked by preincubation of slices
with TrkB-IgG fusion protein, a BDNF scavenger, or coapplication of K
252a, an inhibitor for receptor tyrosine kinases. TrkB-IgG or K252a it
self completely blocked LTP, suggesting that endogenous BDNF or anothe
r TrkB ligand plays a role in LTP in the developing visual cortex.