Alterations of amino acids and glutamate transport in the DBA/2J mouse retina; possible clues to degeneration.
BACKGROUND
The DBA/2J mouse spontaneously develops ocular hypertension and time-dependent progressive retinal ganglion cell (RGC) loss. This study examines changes in amino acid levels in the vitreous, and changes in the expression of retinal glutamate transporters and receptors that occur during the progression of this pathology.


METHODS
Retinas were obtained from DBA/2J mice at ages 3, 6 and 11 months. C57BL/6 mice were used as age-matched controls. Vitreal amino acid content was measured with HPLC. Western blotting and immunohistochemistry were performed using specific antibodies against the glutamate transporters (GLAST, GLT-1v, EAAC-1) and glutamate receptors, particularly NMDA (NR1, NR2A, NR2B) and AMPA (GluR1, GluR2/3, GluR4) receptors.


RESULTS
HPLC showed retinal concentrations of glutamate, glutamine, glycine, alanine, lysine, serine, and arginine to be significantly higher in DBA/2J mice at 11 months of age compared to age-matched controls. Western Blots revealed a moderate decrease of GLAST and GLT-1v expression in DBA/2J mice at 6 and 11 months as compared to age-matched controls while there was no change in EAAC1. Immunohistochemically, no changes in expression of NMDA and AMPA receptors were seen.


CONCLUSIONS
Alterations of amino acid content and enhanced glutamate neurotransmission might be involved in the pathogenesis of retinal neurodegeneration in the DBA/ 2J mouse model of ocular hypertension. Moreover, these mice provide an animal model for studying excitotoxic retinal damage.
Schuettauf
Frank
F
Department of Pathophysiology of Vision and Neuro-Ophthalmology, University Eye Hospital, Schleichstrasse 12, 72076 Tübingen, Germany. fschuettauf@uni-tuebingen.de
Thaler
Sebastian
S
Bolz
Sylvia
S
Fries
Julia
J
Kalbacher
Hubert
H
Mankowska
Anna
A
Zurakowski
David
D
Zrenner
Eberhart
E
Rejdak
Robert
R
D027322:Amino Acid Transport System X-AG / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D001082:Aqueous Humor / Q000378:metabolism; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D004195:Disease Models, Animal; D005260:Female; D007124:Immunoenzyme Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009798:Ocular Hypertension / Q000378:metabolism / Q000473:pathology; D017470:Receptors, Glutamate / Q000378:metabolism*; D012160:Retina / Q000378:metabolism* / Q000473:pathology; D012162:Retinal Degeneration / Q000378:metabolism* / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000378:metabolism / Q000473:pathology
D027322:Amino Acid Transport System X-AG; D000596:Amino Acids; D017470:Receptors, Glutamate