کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10819065 1060345 2005 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Calcium and protein phosphatase 1/2A attenuate N-methyl-d-aspartate receptor activity in the anoxic turtle cortex
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Calcium and protein phosphatase 1/2A attenuate N-methyl-d-aspartate receptor activity in the anoxic turtle cortex
چکیده انگلیسی
Excitotoxic cell death (ECD) is characteristic of mammalian brain following min of anoxia, but is not observed in the western painted turtle following days to months without oxygen. A key event in ECD is a massive increase in intracellular Ca2+ by over-stimulation of N-methyl-d-aspartate receptors (NMDARs). The turtle's anoxia tolerance may involve the prevention of ECD by attenuating NMDAR-induced Ca2+ influx. The goal of this study was to determine if protein phosphatases (PPs) and intracellular calcium mediate reductions in turtle cortical neuron whole-cell NMDAR currents during anoxia, thereby preventing ECD. Whole-cell NMDAR currents did not change during 80 min of normoxia, but decreased 56% during 40 min of anoxia. Okadaic acid and calyculin A, inhibitors of serine/threonine PP1 and PP2A, potentiated NMDAR currents during normoxia and prevented anoxia-mediated attenuation of NMDAR currents. Decreases in NMDAR activity during anoxia were also abolished by inclusion of the Ca2+ chelator - BAPTA and the calmodulin inhibitor - calmidazolium. However, cypermethrin, an inhibitor of the Ca2+/calmodulin-dependent PP2B (calcineurin), abolished the anoxic decrease in NMDAR activity at 20, but not 40 min suggesting that this phosphatase might play an early role in attenuating NMDAR activity during anoxia. Our results show that PPs, Ca2+ and calmodulin play an important role in decreasing NMDAR activity during anoxia in the turtle cortex. We offer a novel mechanism describing this attenuation in which PP1 and 2A dephosphorylate the NMDAR (NR1 subunit) followed by calmodulin binding, a subsequent dissociation of α-actinin-2 from the NR1 subunit, and a decrease in NMDAR activity.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology - Volume 142, Issue 1, September 2005, Pages 50-57
نویسندگان
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