Brain-derived neurotrophic factor enhances long-term potentiation in rat visual cortex.
Brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), members of the nerve growth factor (NGF) gene family, have been suggested to play a role in experience-dependent modification of neural networks in the developing nervous system. In this study we addressed the question of whether these neurotrophins are involved in long-term potentiation (LTP) in developing visual cortex. We recorded layer II/III field potentials and whole-cell currents evoked by test stimulation of layer IV at 0.1 Hz in visual cortical slices prepared from young rats (postnatal day 15-25) and observed effects of BDNF, NT-3, and NGF on these 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 BDNF application. At the concentration of 20 ng/ml, BDNF did not show such an effect, but it enhanced the magnitude of expressed LTP. On the other hand, NT-3 and NGF had none of these effects. Immunohistochemical staining of slices with antibody against BDNF showed that exogenous BDNF penetrated into the whole slice within approximately 5 min of its application. The actions of BDNF were blocked by preincubation of slices with TrkB-IgG fusion protein, a BDNF scavenger, or coapplication of K252a, an inhibitor for receptor tyrosine kinases. TrkB-IgG or K252a itself completely blocked LTP, suggesting that endogenous BDNF or another TrkB ligand plays a role in LTP in the developing visual cortex.
Akaneya
Y
Y
Department of Neurophysiology, Biomedical Research Center, Osaka University Medical School, Suita City, 565 Japan.
Tsumoto
T
T
Kinoshita
S
S
Hatanaka
H
H
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000831:Animals, Newborn; D019208:Brain-Derived Neurotrophic Factor / Q000493:pharmacokinetics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D013997:Time Factors; D014793:Visual Cortex / Q000187:drug effects* / Q000378:metabolism
D019208:Brain-Derived Neurotrophic Factor