title: Hypoxia induces an increase in intracellular magnesium via transient receptor potential melastatin 7 (TRPM7) channels in rat hippocampal neurons in vitro.
abstract: TRPM7, a divalent cation channel, plays an important role in neurons damaged from cerebral ischemia due to permitting intracellular calcium overload. This study aimed to explore whether magnesium was transported via a TRPM7 channel into the intracellular space of rat hippocampal neurons after 1 h of oxygen-glucose deprivation (OGD) and acute chemical ischemia (CI) by using methods of the Mg(2+) fluorescent probe Mag-Fura-2 to detect intracellular magnesium concentration ([Mg(2+)](i)) and flame atomic absorption spectrometry to measure extracellular magnesium concentration ([Mg(2+)](o)). The results showed that the neuronal [Mg(2+)](i) was 1.51-fold higher after 1 h of OGD at a basal level, and the increase of neuronal [Mg(2+)](i) reached a peak after 1 h of OGD and was kept for 60 min with re-oxygenation. Meanwhile, the [Mg(2+)](o) decreased after 1 h of OGD and recovered to the pre-ischemic level within 15 min after re-oxygenation. In the case of CI, the [Mg(2+)](i) peak immediately appeared in hippocampal neurons. This increase of [Mg(2+)](i) declined by removing extracellular magnesium in OGD or CI. Furthermore, by using Gd(3+) or 2-aminoethoxydiphenyl borate to inhibit TRPM7 channels, the [Mg(2+)](i) increase, which was induced by OGD or CI, was attenuated without altering the basal level of [Mg(2+)](i). By silencing TRPM7 with shRNA in hippocampal neurons, it was found that not only was the increase of [Mg(2+)](i) induced by OGD or CI but also the basal levels of [Mg(2+)](i) were attenuated. In contrast, overexpression of TRPM7 in HEK293 cells exaggerated both the basal levels and increased [Mg(2+)](i) after 1 h of OGD/CI. These results suggest that anoxia induced the increase of [Mg(2+)](i) via TRPM7 channels in rat hippocampal neurons.
authors.affiliation: Department of Neurobiology and Key Laboratory of Neurological Disease of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Fengbo
authors.initials: F
authors.lastname: Zhao
authors.forename: Yin
authors.initials: Y
authors.lastname: Zhao
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Lei
authors.initials: L
authors.lastname: Pei
authors.forename: Ning
authors.initials: N
authors.lastname: Sun
authors.forename: Jing
authors.initials: J
authors.lastname: Shi
mesh_terms: D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D020868:Gene Silencing; D005947:Glucose / Q000494:pharmacology; D057809:HEK293 Cells; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D017136:Ion Transport / Q000187:drug effects / Q000502:physiology; D008274:Magnesium / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D051381:Rats; D013549:Sweetening Agents; D050053:TRPM Cation Channels / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D013549:Sweetening Agents; D050053:TRPM Cation Channels; D017346:Protein Serine-Threonine Kinases; C486583:TRPM7 protein, human; C486584:Trpm7 protein, rat; D008274:Magnesium; D005947:Glucose