Brain-derived neurotrophic factor triggers a rapid glutamate release through increase of intracellular Ca(2+) and Na(+) in cultured cerebellar neurons.
We reported previously that BDNF induced glutamate release was dependent on intracellular Ca(2+) but not extracellular Ca(2+) in cerebellar neurons (Numakawa et al., 1999). It was revealed that the release was through a non-exocytotic pathway (Takei et al., 1998; Numakawa et al., 1999). In the present study, we monitored the dynamics of intracellular Ca(2+) and Na(+) in cerebellar neurons, and investigated the possibility of reverse transport of glutamate mediated by BDNF. As reported, BDNF increased the intracellular Ca(2+) level. We found that the Ca(2+) increase induced by BDNF was completely blocked by xestospongin C, an IP(3) receptor antagonist, and U-73122, a PLC-gamma inhibitor. Xestospongin C and U-73122 also blocked the BDNF-dependent glutamate release, suggesting that the BDNF-induced transient increase of Ca(2+) through the activation of the PLC-gamma/ IP(3) pathway was essential for the glutamate release. We found that BDNF induced a Na(+) influx. This was blocked by treatment with TTX. U-73122 and xestospongin C blocked the BDNF-induced Na(+) influx, suggesting that the Na(+)influx required the BDNF-induced Ca(2+) increase. Next, we examined the possibility that a co-transporter of Na(+) and glutamate was involved in the BDNF-induced glutamate release. BDNF-induced glutamate release was blocked by L-trans-pyrollidine-2,4-dicalboxylic acid (t-PDC), a glutamate transporter inhibitor, whereas neither the 4-aminopyridine (4AP)- nor high potassium (HK(+))-induced release was blocked by t-PDC. In addition, DL-threo-beta-benzyloxyaspartate (DL-TBOA) also blocked the BDNF-mediated glutamate release, suggesting that reverse transport of glutamate may be involved. All the results therefore suggest that Na(+)-dependent reverse transport contributes to BDNF-mediated transmitter release through the PLC-gamma/IP(3)-mediated Ca(2+) signaling.
Numakawa
T
T
Division of Protein Biosynthesis, Institute for Protein Research, Osaka University, Suita, Osaka, Japan. numakawa@protein.osaka-u.ac.jp
Matsumoto
T
T
Adachi
N
N
Yokomaku
D
D
Kojima
M
M
Takei
N
N
Hatanaka
H
H
D027322:Amino Acid Transport System X-AG / Q000378:metabolism; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D047028:Macrocyclic Compounds; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010080:Oxazoles / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D051966:Phospholipase C gamma; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
D027322:Amino Acid Transport System X-AG; D019208:Brain-Derived Neurotrophic Factor; D015220:Calcium Channels; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D004963:Estrenes; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007476:Ionophores; D007527:Isoenzymes; D047028:Macrocyclic Compounds; D010080:Oxazoles; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; D018160:Receptors, Cytoplasmic and Nuclear; C108644:xestospongin A; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D018698:Glutamic Acid; D004533:Egtazic Acid; D015759:Ionomycin; D019284:Thapsigargin; D012964:Sodium; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D002118:Calcium