Nerve growth factor inhibits Gd(3+)-sensitive calcium influx and reduces chemical anoxic neuronal death.
To investigate whether glutamate and voltage-gated calcium channels-independent calcium influx exists during acute anoxic neuronal damage and its possible relationship to neuronal protective function of NGF. In in vitro model of acute anoxia, hippocampal cultures from newborn rats were exposed to 3 mmol/L KCN. Changes of intracellular Ca(2+) concentration ([Ca(2+)](i)) were monitored by con-focal imaging and cell viability was assayed by PI and cFDA staining. The results showed that after treatment with primary hippocampal cultures with 3 mmol/L KCN for 15 min, [Ca(2+)](i) was significantly increased 6.27-fold compared to pre-anoxia level and 73.3% of the cells died. When combination of 20 micromol/L MK-801 (glutamate receptor antagonist), 40 micromol/L CNQX (AMPA receptor antagonist) and 5 micromol/L nimodipine (voltage-gated calcium channel antagonist) (hereafter denoted as MCN) were administrated to hippocampal cultures, levels of [Ca(2+)](i) and cell death rate induced by KCN were partially reduced by 35.9% and 47.5% respectively. However, Gd(3+) (10 micromol/L) almost completely blocked KCN-mediated [Ca(2+)](i) elevation by 81.9% and reduced neuronal death by 88.8% in the presence of MCN. It is noteworthy that NGF, used in combination with MCN, inhibited KCN-induced [Ca(2+)](i) increase by 77.4% and reduced cell death by 87.1%. Only PLC inhibitor U73122 (10 micromol/L) abolished NGF effects. It is concluded that Gd(3+)-sensitive calcium influx, which is NMDA (glutamate receptor) and voltage-gated calcium channels-independent, is responsible for acute anoxic neuronal death. NGF can inhibit Gd(3+)-sensitive calcium influx and reduce anoxic neuronal death through activating PLC pathway.
Jiang
Hui
H
Department of Neurobiology and Key Laboratory of Neurological Diseases of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China. rosehui1218@yahoo.com.cn
Tian
Shunlian
S
Zeng
Yan
Y
Shi
Jing
J
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia; D002478:Cells, Cultured; D018691:Excitatory Amino Acid Antagonists / Q000378:metabolism; D005682:Gadolinium / Q000494:pharmacology*; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology* / Q000378:metabolism; D009410:Nerve Degeneration; D020932:Nerve Growth Factor / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D018691:Excitatory Amino Acid Antagonists; D018696:Neuroprotective Agents; D018698:Glutamic Acid; D020932:Nerve Growth Factor; D005682:Gadolinium; D002118:Calcium