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The GluN3A subunit exerts a neuroprotective effect in brain ischemia and the hypoxia process.

Wang H, Yan H, Zhang S, Wei X, Zheng J, Li J - ASN Neuro (2013)

Bottom Line: GluN3 subunits, the third member of the NMDAR family with two isoforms, GluN3A and GluN3B, have been confirmed to display an inhibitory effect on NMDAR activity.It was found that GluN3A protein expression in rat hippocampus and the prefrontal cortex was increased quickly after brain ischemia and remained at a high level for at least 24 h.Suppressing the generation of hydroxyl radicals and NO (nitric oxide) is probably also involved in the neuroprotection.

View Article: PubMed Central - PubMed

Affiliation: Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, People's Republic of China.

ABSTRACT
NMDARs (N-methyl-D-aspartate receptors) mediate the predominantly excitatory neurotransmission in the CNS (central nervous system). Excessive release of glutamate and overactivation of NMDARs during brain ischemia and the hypoxia process are causally linked to excitotoxicity and neuronal damage. GluN3 subunits, the third member of the NMDAR family with two isoforms, GluN3A and GluN3B, have been confirmed to display an inhibitory effect on NMDAR activity. However, the effect of GluN3 subunits in brain ischemia and hypoxia is not clearly understood. In the present study, the influence of ischemia and hypoxia on GluN3 subunit expression was observed by using the 2VO (two-vessel occlusion) rat brain ischemia model and cell OGD (oxygen and glucose deprivation) hypoxia model. It was found that GluN3A protein expression in rat hippocampus and the prefrontal cortex was increased quickly after brain ischemia and remained at a high level for at least 24 h. However, the expression of the GluN3B subunit was not remarkably changed in both the animal and cell models. After OGD exposure, rat hippocampal neurons with GluN3A subunit overexpression displayed more viability than the wild-type neurons. NG108-15 cells overexpressing GluN3A presented pronounced resistance to glutamate insult. Blocking the increase of intracellular Ca2+ concentration may underlie the neuroprotective mechanism of up-regulated GluN3A subunit. Suppressing the generation of hydroxyl radicals and NO (nitric oxide) is probably also involved in the neuroprotection.

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Possible mechanisms involved in the protective ability of GluN3A(A) Intracellular Ca2+ ion changes in NG108-15 cells overexpressing or not overexpressing GluN3A subunits after glutamate injury. Data were record at 2 s intervals for 4 min while glutamate and glycine were added. (B) After glutamate injury, a large amount of Ca2+ flowed into cells (B2, bright green) compared with the original status (B1, dark green) in WT (wild-type) cells. (C) Little change of intracellular Ca2+ signal in GluN3A overexpressing cells before (C1) and after (C2) glutamate injury. (D, E) Changes of hydroxyl radical and NO after glutamate injury. NG108-15 cells with or without GluN3A overexpression were monitored, and sample absorbance was converted to a change ratio. Data were presented as means±S.E.M., **P<0.01 relative to vector alone (control).
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Figure 8: Possible mechanisms involved in the protective ability of GluN3A(A) Intracellular Ca2+ ion changes in NG108-15 cells overexpressing or not overexpressing GluN3A subunits after glutamate injury. Data were record at 2 s intervals for 4 min while glutamate and glycine were added. (B) After glutamate injury, a large amount of Ca2+ flowed into cells (B2, bright green) compared with the original status (B1, dark green) in WT (wild-type) cells. (C) Little change of intracellular Ca2+ signal in GluN3A overexpressing cells before (C1) and after (C2) glutamate injury. (D, E) Changes of hydroxyl radical and NO after glutamate injury. NG108-15 cells with or without GluN3A overexpression were monitored, and sample absorbance was converted to a change ratio. Data were presented as means±S.E.M., **P<0.01 relative to vector alone (control).

Mentions: Fluo4-AM served as a Ca2+ indicator and was used to monitor changes in intracellular Ca2+ levels after glutamate insult. Wild-type cells turned bright green quickly, indicating influx of large amounts of Ca2+ into cells (Figures 8A and 8B). However no such obvious changes occurred in cells overexpressing GluN3A or cells pretreated with MK-801. This suggested that cells overexpressing GluN3A were less permeable to Ca2+. Figures 8(D) and 8(E) show changes in the concentrations of hydroxyl radicals and NO after glutamate injury in each group. Compared with wild-type cells, the concentrations of hydroxyl radicals and NO level in cells overexpressing GluN3A decreased from 567±14 and 49.7±1.6% to 437±8.6 and 28.0±1% after glutamate insult, respectively (P<0.05, n=3).


The GluN3A subunit exerts a neuroprotective effect in brain ischemia and the hypoxia process.

Wang H, Yan H, Zhang S, Wei X, Zheng J, Li J - ASN Neuro (2013)

Possible mechanisms involved in the protective ability of GluN3A(A) Intracellular Ca2+ ion changes in NG108-15 cells overexpressing or not overexpressing GluN3A subunits after glutamate injury. Data were record at 2 s intervals for 4 min while glutamate and glycine were added. (B) After glutamate injury, a large amount of Ca2+ flowed into cells (B2, bright green) compared with the original status (B1, dark green) in WT (wild-type) cells. (C) Little change of intracellular Ca2+ signal in GluN3A overexpressing cells before (C1) and after (C2) glutamate injury. (D, E) Changes of hydroxyl radical and NO after glutamate injury. NG108-15 cells with or without GluN3A overexpression were monitored, and sample absorbance was converted to a change ratio. Data were presented as means±S.E.M., **P<0.01 relative to vector alone (control).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3756525&req=5

Figure 8: Possible mechanisms involved in the protective ability of GluN3A(A) Intracellular Ca2+ ion changes in NG108-15 cells overexpressing or not overexpressing GluN3A subunits after glutamate injury. Data were record at 2 s intervals for 4 min while glutamate and glycine were added. (B) After glutamate injury, a large amount of Ca2+ flowed into cells (B2, bright green) compared with the original status (B1, dark green) in WT (wild-type) cells. (C) Little change of intracellular Ca2+ signal in GluN3A overexpressing cells before (C1) and after (C2) glutamate injury. (D, E) Changes of hydroxyl radical and NO after glutamate injury. NG108-15 cells with or without GluN3A overexpression were monitored, and sample absorbance was converted to a change ratio. Data were presented as means±S.E.M., **P<0.01 relative to vector alone (control).
Mentions: Fluo4-AM served as a Ca2+ indicator and was used to monitor changes in intracellular Ca2+ levels after glutamate insult. Wild-type cells turned bright green quickly, indicating influx of large amounts of Ca2+ into cells (Figures 8A and 8B). However no such obvious changes occurred in cells overexpressing GluN3A or cells pretreated with MK-801. This suggested that cells overexpressing GluN3A were less permeable to Ca2+. Figures 8(D) and 8(E) show changes in the concentrations of hydroxyl radicals and NO after glutamate injury in each group. Compared with wild-type cells, the concentrations of hydroxyl radicals and NO level in cells overexpressing GluN3A decreased from 567±14 and 49.7±1.6% to 437±8.6 and 28.0±1% after glutamate insult, respectively (P<0.05, n=3).

Bottom Line: GluN3 subunits, the third member of the NMDAR family with two isoforms, GluN3A and GluN3B, have been confirmed to display an inhibitory effect on NMDAR activity.It was found that GluN3A protein expression in rat hippocampus and the prefrontal cortex was increased quickly after brain ischemia and remained at a high level for at least 24 h.Suppressing the generation of hydroxyl radicals and NO (nitric oxide) is probably also involved in the neuroprotection.

View Article: PubMed Central - PubMed

Affiliation: Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, People's Republic of China.

ABSTRACT
NMDARs (N-methyl-D-aspartate receptors) mediate the predominantly excitatory neurotransmission in the CNS (central nervous system). Excessive release of glutamate and overactivation of NMDARs during brain ischemia and the hypoxia process are causally linked to excitotoxicity and neuronal damage. GluN3 subunits, the third member of the NMDAR family with two isoforms, GluN3A and GluN3B, have been confirmed to display an inhibitory effect on NMDAR activity. However, the effect of GluN3 subunits in brain ischemia and hypoxia is not clearly understood. In the present study, the influence of ischemia and hypoxia on GluN3 subunit expression was observed by using the 2VO (two-vessel occlusion) rat brain ischemia model and cell OGD (oxygen and glucose deprivation) hypoxia model. It was found that GluN3A protein expression in rat hippocampus and the prefrontal cortex was increased quickly after brain ischemia and remained at a high level for at least 24 h. However, the expression of the GluN3B subunit was not remarkably changed in both the animal and cell models. After OGD exposure, rat hippocampal neurons with GluN3A subunit overexpression displayed more viability than the wild-type neurons. NG108-15 cells overexpressing GluN3A presented pronounced resistance to glutamate insult. Blocking the increase of intracellular Ca2+ concentration may underlie the neuroprotective mechanism of up-regulated GluN3A subunit. Suppressing the generation of hydroxyl radicals and NO (nitric oxide) is probably also involved in the neuroprotection.

Show MeSH
Related in: MedlinePlus