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Neonatal seizures alter NMDA glutamate receptor GluN2A and 3A subunit expression and function in hippocampal CA1 neurons.

Zhou C, Sun H, Klein PM, Jensen FE - Front Cell Neurosci (2015)

Bottom Line: Moreover, GluN eEPSCs showed a decreased sensitivity to GluN2B selective antagonists and decreased Mg(2+) sensitivity at negative holding potentials, indicating a higher proportion of GluN2A and GluN3A subunit function, respectively.These physiological findings were accompanied by a concurrent increase in GluN2A phosphorylation and GluN3A protein.These results suggest that altered GluN function and expression could potentially contribute to future epileptogenesis following neonatal seizures, and may represent potential therapeutic targets for the blockade of future epileptogenesis in the developing brain.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Division of Neuroscience, Boston Children's Hospital Boston, MA, USA ; Program in Neurobiology, Harvard Medical School Boston, MA, USA.

ABSTRACT
Neonatal seizures are commonly caused by hypoxic and/or ischemic injury during birth and can lead to long-term epilepsy and cognitive deficits. In a rodent hypoxic seizure (HS) model, we have previously demonstrated a critical role for seizure-induced enhancement of the AMPA subtype of glutamate receptor (GluA) in epileptogenesis and cognitive consequences, in part due to GluA maturational upregulation of expression. Similarly, as the expression and function of the N-Methyl-D-aspartate (NMDA) subtype of glutamate receptor (GluN) is also developmentally controlled, we examined how early life seizures during the critical period of synaptogenesis could modify GluN development and function. In a postnatal day (P)10 rat model of neonatal seizures, we found that seizures could alter GluN2/3 subunit composition of GluNs and physiological function of synaptic GluNs. In hippocampal slices removed from rats within 48-96 h following seizures, the amplitudes of synaptic GluN-mediated evoked excitatory postsynaptic currents (eEPSCs) were elevated in CA1 pyramidal neurons. Moreover, GluN eEPSCs showed a decreased sensitivity to GluN2B selective antagonists and decreased Mg(2+) sensitivity at negative holding potentials, indicating a higher proportion of GluN2A and GluN3A subunit function, respectively. These physiological findings were accompanied by a concurrent increase in GluN2A phosphorylation and GluN3A protein. These results suggest that altered GluN function and expression could potentially contribute to future epileptogenesis following neonatal seizures, and may represent potential therapeutic targets for the blockade of future epileptogenesis in the developing brain.

No MeSH data available.


Related in: MedlinePlus

Hypoxic seizures-induced increases in GluN2A subunit phosphorylation at 48–96 h post-HS. (A–C) Western blot quantification of total and Phospho-GluN2A subunit (Y1387) in micro-disected hippocampus CA1 from control and 48–96 h post-HS rats (n = 20, 20). *p < 0.05. Error bars indicate S.E.M. (D–F) Western blot quantification of total and Phospho-GluN2B subunit (Y1472) in micro-dissected hippocampus CA1 from control and 48–96 h post-HS rats (n = 10, 10). Error bars indicate S.E.M.
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Figure 3: Hypoxic seizures-induced increases in GluN2A subunit phosphorylation at 48–96 h post-HS. (A–C) Western blot quantification of total and Phospho-GluN2A subunit (Y1387) in micro-disected hippocampus CA1 from control and 48–96 h post-HS rats (n = 20, 20). *p < 0.05. Error bars indicate S.E.M. (D–F) Western blot quantification of total and Phospho-GluN2B subunit (Y1472) in micro-dissected hippocampus CA1 from control and 48–96 h post-HS rats (n = 10, 10). Error bars indicate S.E.M.

Mentions: To further confirm the post-HS changes in NMDA receptor GluN2A/B subunit composition, we analyzed the membrane protein expression levels of GluN2A and 2B in the microdissected hippocampal CA1 region from 48–96 h post-HS rats and their littermate controls. We found that GluN2A subunit expression in 1 through to 96 h post-HS rats did not show significant changes compared to their littermate controls (P10–11 controls: 100 ± 16.96%; 1–24 h post-HS rats: 155.22 ± 27.21%, n = 20, p = 0.09 and P12–14 controls: 100 ± 12.08%; 48–96 h post-HS rats: 135.66 ± 21.06%, n = 20, p = 0.15, Figure 3A). However, GluN2A phosphorylation at Y1387 in CA1 region at 48–72 h post-HS was significantly increased compared to P12–14 control levels (P12–14 controls: 100 ± 11.31%; 48–96 h post-HS rats: 170.28 ± 12.21%, n = 20, p = 0.001, Figure 3B), not at 1–24 h (P10–11 controls: 100 ± 14.38%; 1–24 h post-HS rats: 137.98 ± 12.13%, n = 20, p = 0.07). GluN2A tyrosine (Y1387) phosphorylation functions to incorporate GluN2A subunits into GluNs and enhances GluN function (Chen and Roche, 2007; Zhou et al., 2007; Zhang et al., 2008; Sanz-Clemente et al., 2010, 2013). Our results suggest an increase in GluN2A function at 48–96 h following HS.


Neonatal seizures alter NMDA glutamate receptor GluN2A and 3A subunit expression and function in hippocampal CA1 neurons.

Zhou C, Sun H, Klein PM, Jensen FE - Front Cell Neurosci (2015)

Hypoxic seizures-induced increases in GluN2A subunit phosphorylation at 48–96 h post-HS. (A–C) Western blot quantification of total and Phospho-GluN2A subunit (Y1387) in micro-disected hippocampus CA1 from control and 48–96 h post-HS rats (n = 20, 20). *p < 0.05. Error bars indicate S.E.M. (D–F) Western blot quantification of total and Phospho-GluN2B subunit (Y1472) in micro-dissected hippocampus CA1 from control and 48–96 h post-HS rats (n = 10, 10). Error bars indicate S.E.M.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4585040&req=5

Figure 3: Hypoxic seizures-induced increases in GluN2A subunit phosphorylation at 48–96 h post-HS. (A–C) Western blot quantification of total and Phospho-GluN2A subunit (Y1387) in micro-disected hippocampus CA1 from control and 48–96 h post-HS rats (n = 20, 20). *p < 0.05. Error bars indicate S.E.M. (D–F) Western blot quantification of total and Phospho-GluN2B subunit (Y1472) in micro-dissected hippocampus CA1 from control and 48–96 h post-HS rats (n = 10, 10). Error bars indicate S.E.M.
Mentions: To further confirm the post-HS changes in NMDA receptor GluN2A/B subunit composition, we analyzed the membrane protein expression levels of GluN2A and 2B in the microdissected hippocampal CA1 region from 48–96 h post-HS rats and their littermate controls. We found that GluN2A subunit expression in 1 through to 96 h post-HS rats did not show significant changes compared to their littermate controls (P10–11 controls: 100 ± 16.96%; 1–24 h post-HS rats: 155.22 ± 27.21%, n = 20, p = 0.09 and P12–14 controls: 100 ± 12.08%; 48–96 h post-HS rats: 135.66 ± 21.06%, n = 20, p = 0.15, Figure 3A). However, GluN2A phosphorylation at Y1387 in CA1 region at 48–72 h post-HS was significantly increased compared to P12–14 control levels (P12–14 controls: 100 ± 11.31%; 48–96 h post-HS rats: 170.28 ± 12.21%, n = 20, p = 0.001, Figure 3B), not at 1–24 h (P10–11 controls: 100 ± 14.38%; 1–24 h post-HS rats: 137.98 ± 12.13%, n = 20, p = 0.07). GluN2A tyrosine (Y1387) phosphorylation functions to incorporate GluN2A subunits into GluNs and enhances GluN function (Chen and Roche, 2007; Zhou et al., 2007; Zhang et al., 2008; Sanz-Clemente et al., 2010, 2013). Our results suggest an increase in GluN2A function at 48–96 h following HS.

Bottom Line: Moreover, GluN eEPSCs showed a decreased sensitivity to GluN2B selective antagonists and decreased Mg(2+) sensitivity at negative holding potentials, indicating a higher proportion of GluN2A and GluN3A subunit function, respectively.These physiological findings were accompanied by a concurrent increase in GluN2A phosphorylation and GluN3A protein.These results suggest that altered GluN function and expression could potentially contribute to future epileptogenesis following neonatal seizures, and may represent potential therapeutic targets for the blockade of future epileptogenesis in the developing brain.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Division of Neuroscience, Boston Children's Hospital Boston, MA, USA ; Program in Neurobiology, Harvard Medical School Boston, MA, USA.

ABSTRACT
Neonatal seizures are commonly caused by hypoxic and/or ischemic injury during birth and can lead to long-term epilepsy and cognitive deficits. In a rodent hypoxic seizure (HS) model, we have previously demonstrated a critical role for seizure-induced enhancement of the AMPA subtype of glutamate receptor (GluA) in epileptogenesis and cognitive consequences, in part due to GluA maturational upregulation of expression. Similarly, as the expression and function of the N-Methyl-D-aspartate (NMDA) subtype of glutamate receptor (GluN) is also developmentally controlled, we examined how early life seizures during the critical period of synaptogenesis could modify GluN development and function. In a postnatal day (P)10 rat model of neonatal seizures, we found that seizures could alter GluN2/3 subunit composition of GluNs and physiological function of synaptic GluNs. In hippocampal slices removed from rats within 48-96 h following seizures, the amplitudes of synaptic GluN-mediated evoked excitatory postsynaptic currents (eEPSCs) were elevated in CA1 pyramidal neurons. Moreover, GluN eEPSCs showed a decreased sensitivity to GluN2B selective antagonists and decreased Mg(2+) sensitivity at negative holding potentials, indicating a higher proportion of GluN2A and GluN3A subunit function, respectively. These physiological findings were accompanied by a concurrent increase in GluN2A phosphorylation and GluN3A protein. These results suggest that altered GluN function and expression could potentially contribute to future epileptogenesis following neonatal seizures, and may represent potential therapeutic targets for the blockade of future epileptogenesis in the developing brain.

No MeSH data available.


Related in: MedlinePlus