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Background/aims: D-aspartate is an important candidate for retinal neurotransmitter or neuromodulator. The purpose of this study was to investigate the cells type and distribution of the D-aspartate-immunopositive cells in the ganglion cell layer., Methods: Wister rats were fixed by perfusion with 5% glutaraldehyde. Paraffin sections of the retina were immunohistochemically double-labeled using D-aspartate and glutamate or γ-aminobutyric acid antibodies. After labeling the whole-mount retina by D-aspartate, the cell densities of both the perivascular and nonperivascular areas in the ganglion cell layer were measured for the central, midperipheral, and peripheral zones, respectively., Results: Within the paraffin section, some of the glutamate-immunoreactive cells in the ganglion cell layer were D-aspartate immunoreactive. These D-aspartate-positive cells in the ganglion cell layer were more frequently observed along the retinal vessels in the whole-mount retina. The D-aspartate-positive cell densities in the perivascular area were significantly higher than those in the nonperivascular area for the central, midperipheral, and peripheral zones (p < 0.0001)., Conclusion: In the ganglion cell layer, the D-aspartate-immunopositive cells proved to be the ganglion cells, with their distribution found to be denser along the large retinal vessels such as the arterioles or venules., (Copyright © 2010 S. Karger AG, Basel.)

Aim: The present study investigates whether glutamate immunoreactivity (IR) in the cat outer retina, which is devoid of blood vessels, can be well preserved by perfusion fixation., Methods: Adult cats were perfused intracardially for 1, 5, 10, 15 and 30 min with physiological saline and were subsequently perfused with a mixture of 1% glutaraldehyde and 4% formaldehyde. After the fixation, the retinas were immunocytochemically examined., Results: The photoreceptor inner segments in the retina, which was perfused by saline for 1 and 5 min prior to fixation, showed no glutamate IR. However, those in the retina which was perfused by saline for 10 min showed moderate glutamate IR as found in the retina fixed by immersion. The glutamate IR in the inner segments decreased with a saline perfusion of more than 10 min., Conclusions: Perfusion fixation can well preserve glutamate IR even in the outer retina including the inner segments.

Purpose: To investigate the distribution of amino acids (glutamate, aspartate, glutamine, GABA, glycine) in detached retinas with minimum postmortem artifact and to clarify the relation between amino acid distribution and histopathological change in the outer portion of detached retinas., Methods: Unilateral retinal detachment was produced in cats by injecting 0.25% sodium hyaluronate into the subretinal space using a glass micropipet. The eyes were fixed by perfusion for 10 min, 1, 3, 6 and 24 h, 2, 3 and 7 days after detachment and then examined under conventional light- and electron-microscopic immunocytochemistry., Results: For glutamate, aspartate and glutamine, the inner segments and perikarya of the photoreceptor cells, which were not immunopositive in the normal retinas, showed various degrees of immunoreactivity immediately after retinal detachment. Photoreceptor cells with the strong immunoreactivity developed necrosis. The staining pattern of GABA and glycine scarcely changed during the course of retinal detachment., Conclusions: Excess intracellular glutamate, aspartate and glutamine in photoreceptor cells may cause a part of neuronal death after retinal detachment.

Purpose: To detect early diabetic damage in type 2 diabetes mellitus patients with no diabetic retinopathy (NDR) using optical coherence tomography (OCT) and to evaluate OCT as a clinical test., Methods: Thirty-two patients with NDR (n = 32) were enrolled. We examined retinal and retinal nerve fiber layer (RNFL) thickness using OCT. Two healthy normal populations were also enrolled for the retinal thickness (n = 48) and RNFL thickness (n = 34). Both OCT measurements were obtained in four areas (temporal, superior, nasal and inferior). The receiver operator characteristic (ROC) curve was generated to evaluate the predictor variables., Results: Comparing the normal and NDR eyes, retinal thickness significantly increased (p = 0.03) and RNFL thickness significantly decreased (p = 0.02) in the superior areas. The area under the ROC curve was 0.65 for the superior retinal thickness and 0.63 for the superior RNFL thickness., Conclusions: Both OCT measurements can detect early retinal damage in NDR patients., (Copyright 2005 S. Karger AG, Basel.)