Benzodiazepine and kainate receptor binding sites in the RCS rat retina.
BACKGROUND
The effect of age and photoreceptor degeneration on the kainate subtype of glutamate receptors and on the benzodiazepine-sensitive gamma-aminobutyric acid-A receptors (GABA(A)) in normal and RCS (Royal College of Surgeons) rats were investigated.


METHODS
[(3)H]Kainate and [(3)H]flunitrazepam were used as radioligands for kainate and GABA(A)/benzodiazepine()receptors, respectively, using the quantitative receptor autoradiography technique.


RESULTS
In both normal and RCS rat retina we observed that [(3)Eta]flunitrazepam and [(3)Eta]kainate binding levels were several times higher in inner plexiform layer (IPL) than in outer plexiform layer (OPL) at all four ages studied (P17, P35, P60 and P180). Age-related changes in receptor binding were observed in normal rat retina: [(3)Eta]flunitrazepam binding showed a significant decrease of 25% between P17 and P60 in IPL,and [(3)Eta]kainate binding showed significant decreases between P17 and P35 in both synaptic layers (71% in IPL and 63% in OPL). Degeneration-related changes in benzodiazepine and kainate receptor binding were observed in RCS rat retina. In IPL, [(3)Eta]flunitrazepam and [(3)Eta]kainate binding levels were higher than in normal retina at P35 (by 24% and 86%, respectively). In OPL, [(3)Eta]flunitrazepam binding was higher in RCS than in normal retina on P35 (74%) and also on P60 (62%).


CONCLUSIONS
The results indicate that postnatal changes occur in kainate and benzodiazepine receptor binding sites in OPL and IPL of the rat retina up to 6 months of age. The data also suggest that the receptor binding changes observed in the RCS retina could be a consequence of the primary photoreceptor degeneration.
Stasi
Kalliopi
K
Department of Physiology, Faculty of Medicine, University of Patras, 26500, Patras, Greece. kalliopi.stasi@mssm.edu
Naskar
Rita
R
Thanos
Solon
S
Kouvelas
Elias D
ED
Mitsacos
Ada
A
D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D005445:Flunitrazepam / Q000378:metabolism; D007608:Kainic Acid / Q000378:metabolism; D051381:Rats; D011922:Rats, Mutant Strains; D011963:Receptors, GABA-A / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*; D012162:Retinal Degeneration / Q000378:metabolism*
D005445:Flunitrazepam; D007608:Kainic Acid; D011963:Receptors, GABA-A; D018092:Kainic Acid Receptors