Neural depolarization triggers Mg2+ influx in rat hippocampal neurons. (3rd December 2015)

• Record Type: Journal Article
• Authors: Yamanaka, R.; Shindo, Y.; Karube, T.; Hotta, K.; Suzuki, K.; Oka, K.
• Is Part Of: Neuroscience. Volume 310(2015)
• Page Start: 731
• Page End: 741
• Publication Date: 2015-12-03
• Subjects: [Ca2+]i intracellular calcium ion concentration -- [Mg2+]i intracellular magnesium ion concentration -- 2-APB 2-aminoethoxydiphenyl borate -- Ar argon -- CREB cAMP response element-binding -- FRET fluorescence resonance energy transfer -- HBSS Hanks' balanced salt solution -- HEPES 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid -- IP3 inositol 1, 4, 5-trisphosphate -- ITO indium-tin oxide -- Mg2+ magnesium ion -- ROI region of interest -- S.D. standard deviation -- TEA tetraethylammonium -- TRPM7 transient receptor potential melastatin 7 -- VSFP2.42 voltage-sensitive fluorescent protein; Mg2+ -- KMG-104 -- fluorescent imaging -- depolarization -- hippocampal neuron -- ITO electrode; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2015.10.001
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Depolarization-induced Mg 2+ influx. No correlation between the amplitudes of Mg 2+ and Ca 2+ responses. Mg 2+ mobilizations mediated by 2-APB-sensitive channels. Abstract: Homeostasis of magnesium ion (Mg 2+ ) plays key roles in healthy neuronal functions, and deficiency of Mg 2+ is involved in various neuronal diseases. In neurons, we have reported that excitotoxicity induced by excitatory neurotransmitter glutamate increases intracellular Mg 2+ concentration ([Mg 2+ ]i ). However, it has not been revealed whether neuronal activity under physiological condition modulates [Mg 2+ ]i . The aim of this study is to explore the direct relationship between neural activity and [Mg 2+ ]i dynamics. In rat primary-dissociated hippocampal neurons, the [Mg 2+ ]i and [Ca 2+ ]i dynamics were simultaneously visualized with a highly selective fluorescent Mg 2+ probe, KMG-104, and a fluorescent Ca 2+ probe, Fura Red, respectively. [Mg 2+ ]i increase concomitant with neural activity by direct current stimulation was observed in neurons plated on an indium-tin oxide (ITO) glass electrode, which enables fluorescent imaging during neural stimulation. The neural activity-dependent [Mg 2+ ]i increase was also detected in neurons whose excitability was enhanced by the treatment of a voltage-gated K + channel blocker, tetraethylammonium (TEA) at the timings of spontaneous Ca 2+ increase. Furthermore, the [Mg 2+ ]i increase was abolished in Mg 2+ -free extracellular medium, indicating [Mg 2+ ]i increase is due to Mg 2+ influx induced by neural activity. The direct neuronal depolarization by veratridine, a Na + channel opener, induced [Mg 2+ ]i increase, and this [Mg 2+ ]i increase was suppressed by the pretreatment of a non-specific Mg 2+ channel inhibitor, 2-aminoethoxydiphenyl borate (2-APB). Overall, activity-dependent [Mg 2+ ]i increase results from Mg 2+ influx through 2-APB-sensitive channels in rat hippocampal neurons.