Diabetes changes the levels of ionotropic glutamate receptors in the rat retina.
OBJECTIVE
Diabetic retinopathy (DR) is a leading cause of vision loss and blindness among adults between the age 20 to 74. Changes in ionotropic glutamate receptor subunit composition can affect retinal glutamatergic neurotransmission and, therefore, contribute to visual impairment. The purpose of this study was to investigate whether diabetes leads to changes in ionotropic glutamate receptor subunit expression at the protein and mRNA level in the rat retina.


METHODS
Changes in the expression of ionotropic glutamate receptor subunits were investigated at the mRNA and protein levels in retinas of streptozotocin (STZ)-induced diabetic and age-matched control rats. Animals were euthanized one, four and 12 weeks after the onset of diabetes. Retinal protein extracts were prepared, and the receptor subunit levels were assessed by western blotting. Transcript levels were assessed by real-time quantitative PCR.


RESULTS
Transcript levels of most ionotropic glutamate receptor subunits were not significantly changed in the retinas of diabetic rats, as compared to age-matched controls but protein levels of alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA), kainate, and N-methyl-D-aspartic acid receptors (NMDA) receptors were found to be altered.


CONCLUSIONS
The results provide evidence that diabetes affects the retinal content of ionotropic glutamate receptor subunits at the protein level. The possible implications of these changes on retinal physiology and visual impairment in DR are discussed.
Santiago
Ana R
AR
Department of Zoology, University of Coimbra, Center for Neuroscience and Cell Biology, Coimbra, Portugal. asantiago@fmed.uc.pt
Gaspar
Joana M
JM
Baptista
Filipa I
FI
Cristóvão
Armando J
AJ
Santos
Paulo F
PF
Kamphuis
Willem
W
Ambrósio
António F
AF
D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003920:Diabetes Mellitus / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000235:genetics / Q000378:metabolism; D017470:Receptors, Glutamate / Q000235:genetics* / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000235:genetics / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism; D012160:Retina / Q000378:metabolism* / Q000473:pathology*
D001786:Blood Glucose; D021122:Protein Subunits; D012333:RNA, Messenger; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate
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