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Long-term changes in glutamatergic synaptic transmission in phenylketonuria
A V Glushakov1, O Glushakova, M Varshney
1Department of Anesthesiology, University of Florida, Gainesville, FL 32610-0254, USA.
Brain : a Journal of Neurology
|January 7, 2005
Summary
Phenylketonuria (PKU) causes elevated phenylalanine (L-Phe) levels, altering brain glutamate receptors. This study reveals changes in NMDA and AMPA receptor expression in PKU mice, potentially explaining cognitive deficits.
Area of Science:
- Neuroscience
- Biochemistry
- Genetics
Background:
- Phenylketonuria (PKU) is a common genetic disorder causing intellectual disability due to phenylalanine buildup.
- The exact cellular mechanisms of PKU-induced brain dysfunction are not fully understood.
- Elevated L-phenylalanine (L-Phe) acutely impairs glutamatergic transmission in neurons.
Purpose of the Study:
- To investigate the chronic effects of elevated L-Phe on postsynaptic glutamate receptors in the PKU brain.
- To determine if changes in glutamate receptor expression correlate with brain dysfunction in PKU.
Main Methods:
- Utilized Pah(enu2) mouse model of PKU.
- Employed liquid chromatography-mass spectrometry, patch-clamp electrophysiology, radioligand binding, and Western blot analyses.
- Analyzed forebrain tissue for L-Phe concentrations and receptor expression.
Main Results:
- PKU mice exhibited significantly higher brain L-Phe levels compared to controls.
- NMDA receptor density was upregulated in PKU mice.
- Expression of NMDA receptor subunits (NR2A) and AMPA receptor subunits (Glu1, Glu2/3) increased, while NR2B decreased.
Conclusions:
- Chronic L-Phe accumulation in PKU alters NMDA and AMPA receptor expression and density.
- These receptor changes may contribute to the impaired brain function observed in PKU.
- Glutamatergic system dysregulation is a key factor in PKU-associated neurological disorders.
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