Hippocampal N-methyl-D-aspartate receptor subunit expression profiles in a mouse model of prenatal alcohol exposure.
BACKGROUND
Although several reports have been published showing prenatal ethanol exposure is associated with alterations in N-methyl-D-aspartate (NMDA) receptor subunit levels and, in a few cases, subcellular distribution, results of these studies are conflicting.


METHODS
We used semi-quantitative immunoblotting techniques to analyze NMDA receptor NR1, NR2A, and NR2B subunit levels in the adult mouse hippocampal formation isolated from offspring of dams who consumed moderate amounts of ethanol throughout pregnancy. We employed subcellular fractionation and immunoprecipitation techniques to isolate synaptosomal membrane- and postsynaptic density protein-95 (PSD-95)-associated pools of receptor subunits.


RESULTS
We found that, compared to control animals, fetal alcohol-exposed (FAE) adult mice had: (i) increased synaptosomal membrane NR1 levels with no change in association of this subunit with PSD-95 and no difference in total NR1 expression in tissue homogenates; (ii) decreased NR2A subunit levels in hippocampal homogenates, but no alterations in synaptosomal membrane NR2A levels and no change in NR2A-PSD-95 association; and (iii) no change in tissue homogenate or synaptosomal membrane NR2B levels but a reduction in PSD-95-associated NR2B subunits. No alterations were found in mRNA levels of NMDA receptor subunits suggesting that prenatal alcohol-associated differences in subunit protein levels are the result of differences in post-transcriptional regulation of subunit localization.


CONCLUSIONS
Our results demonstrate that prenatal alcohol exposure induces selective changes in NMDA receptor subunit levels in specific subcellular locations in the adult mouse hippocampal formation. Of particular interest is the finding of decreased PSD-95-associated NR2B levels, suggesting that synaptic NR2B-containing NMDA receptor concentrations are reduced in FAE animals. This result is consistent with various biochemical, physiological, and behavioral findings that have been linked with prenatal alcohol exposure.
Samudio-Ruiz
Sabrina L
SL
Department of Neurosciences, School of Medicine, University of New Mexico, Albuquerque, New Mexico, USA.
Allan
Andrea M
AM
Sheema
Sheema
S
Caldwell
Kevin K
KK
D000428:Alcohol Drinking / Q000523:psychology; D000818:Animals; D015153:Blotting, Western; D003071:Cognition / Q000502:physiology; D017931:DNA Primers; D018076:DNA, Complementary / Q000096:biosynthesis; D000076122:Disks Large Homolog 4 Protein; D005260:Female; D063647:Fetal Alcohol Spectrum Disorders / Q000235:genetics*; D051528:Guanylate Kinases; D006624:Hippocampus / Q000378:metabolism*; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis / Q000302:isolation & purification; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis* / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
D017931:DNA Primers; D018076:DNA, Complementary; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C120997:NR2A NMDA receptor; C121001:NR2B NMDA receptor; D012333:RNA, Messenger; D016194:Receptors, N-Methyl-D-Aspartate; D051528:Guanylate Kinases