title: IGF-1-Involved Negative Feedback of NR2B NMDA Subunits Protects Cultured Hippocampal Neurons Against NMDA-Induced Excitotoxicity.
abstract: Insulin-like growth factor 1 (IGF-1) is a multifunctional protein involved in neuronal polarity and axonal guidance. In our previous study, it was discovered that IGF-1 alleviated 50-μM NMDA-induced excitotoxicity against neuronal autophagy via depression of NR2B p-Ser1303 activation. However, it was found that NMDA at a higher dose did not cause neuronal autophagy. And, the performance of IGF-1 under severe excitotoxicity still needs to be clarified. In this study, we observed that IGF-1 can salvage the hippocampal neurons in an autophagy-independent manner after 150-μM NMDA exposure using thiazolyl blue tetrazolium bromide (MTT), lactate dehydrogenase (LDH), Western blot assay, and transmission electron microscopy. In addition, over-activation of post-synaptic NMDARs was found with the whole-cell patch clamp recording method. In order to explore whether there is a positive feedback way for post-synaptic NMDARs and the different pathway caused by 150 μM NMDA, the phosphorylation level of Fyn and the phosphorylation site of NR2B were investigated. It was observed that NR2B p-Tyr1472 was increased by the activation of Fyn after 150-μM NMDA exposure. When the neutralizing antibody against NR2B p-Ser1303 was added into the medium, both the activations of Fyn and NR2B p-Tyr1472 were blocked, suggesting NR2B p-Ser1303 may be the initial step of NMDA-induced excitotoxicity. In addition, since IGF-1 can block the initial step of NR2B activation, its effect is concluded to continue with the development of excitotoxicity. Overall, this study strongly indicates that the relationship between different phosphorylation sites of NR2B should be laid more emphasis on, which may be a vital target for the NR2B-involved excitotoxicity.
authors.affiliation: Department of Neurobiology, Department of Physiology and Center of Stroke, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, People's Republic of China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Neurology, Department of Respiratory Medicine, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.affiliation: Department of Neurobiology, Department of Physiology and Center of Stroke, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, People's Republic of China.
authors.forename: Song
authors.initials: S
authors.lastname: Han
authors.affiliation: Department of Neurology, Department of Respiratory Medicine, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, People's Republic of China.
authors.forename: Jianing
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Neurology, Department of Respiratory Medicine, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, People's Republic of China.
authors.forename: Shu
authors.initials: S
authors.lastname: Ding
authors.affiliation: Department of Neurobiology, Department of Physiology and Center of Stroke, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Neurobiology, Department of Physiology and Center of Stroke, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, People's Republic of China. yyling@ccmu.edu.cn.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Yin
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D016202:N-Methylaspartate / Q000633:toxicity*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D021122:Protein Subunits / Q000819:agonists / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000378:metabolism*
chemical_list: D018690:Excitatory Amino Acid Agonists; C121001:NR2B NMDA receptor; D021122:Protein Subunits; D016194:Receptors, N-Methyl-D-Aspartate; C548904:insulin-like growth factor-1, rat; D016202:N-Methylaspartate; D007334:Insulin-Like Growth Factor I
keywords: Excitatory post-synaptic currents (EPSCs); Fyn; Insulin-like growth factor 1 (IGF-1); NMDA; NR2B; Phosphorylation