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- Agardh, Carl-David, et al.
(författare)
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The glutathione levels are reduced in Goto-Kakizaki rat retina, but are not influenced by aminoguanidine treatment
- 1998
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Ingår i: Current Eye Research. - : Informa UK Limited. - 0271-3683 .- 1460-2202. ; 17:3, s. 251-256
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To examine the levels of the free radical protecting enzyme glutathione and the endothelial/pericyte ratio in retinal capillaries in the Goto-Kakizaki (GK) Wistar rat, with and without aminoguanidine treatment. METHODS: Eight-month-old GK rats, with non-obese, spontaneous non-insulin-dependent diabetes mellitus (NIDDM), were examined after a six month period of aminoguanidine treatment. Glutathione levels were measured with high performance liquid chromatography and the endothelial/pericyte ratio was calculated in trypsin digested vessel preparations. RESULTS: The levels of glutathione in GK rat retina were significantly lower compared to controls (p = 0.0108). There was no difference in the endothelial/pericyte ratio compared to matched control rats (1.8 +/- 0.2 vs. 1.8 +/- 0.1, respectively). Aminoguanidine treatment did not influence either the degree of hyperglycemia, the levels of glutathione or the endothelial/pericyte ratio in GK or control rat retina. CONCLUSIONS: The results indicate that impaired glucose metabolism may influence one of the defense mechanisms for oxidative stress, but also suggest that decreased glutathione levels occur prior to morphological signs of pericyte loss and/or endothelial cell proliferation in this animal model of hereditary NIDDM.
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| 2. |
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| 3. |
- Sundelin, Staffan, et al.
(författare)
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Lipofuscin accumulation in cultured retinal pigment epithelial cells reduces their phagocytic capacity
- 1998
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Ingår i: Current Eye Research. - : Informa UK Limited. - 0271-3683 .- 1460-2202. ; 17:8, s. 851-857
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Tidskriftsartikel (refereegranskat)abstract
- Purpose. Retinal pigment epithelial (RPE) cells slowly accumulate lipofuscin pigment within their acidic vacuolar apparatus as a result of extra- and/or intralysosomal oxidative alterations of phagocytosed photoreceptor outer segments (POS) with consequent imperfect degradation of these structures. In old age, lipofuscin accumulation may become quite substantial. It has been suggested that pronounced accumulation of lipofuscin is related to decreased RPE function and, possibly, to age-related macular degeneration. The aim of the present investigation was to study whether heavy loading with lipofuscin of RPE acidic lysosomes would affect the further phagocytic ability of the cells.Methods. In the first section of the investigation, cultures of rabbit RPE cells were exposed daily to bovine UV-irradiated POS (artificial lipofuscin) for 4 weeks, resulting in a pronounced lipofuscin accumulation of the cells. Fluorescent latex beads (labelled with a red fluorophore) were added to unloaded control cultures at 0 and 4 weeks after their establishment, and to lipofuscin loaded cells after 4 weeks of feeding with artificial lipofuscin. Cellular amounts of lipofuscin, and their phagocytotic activity, were quantified by static fluorometry measuring lipofuscin-specific and red bead-specific fluorescence, respectively. The intracellular location of the beads was verified by confocal laser scanning microscopy.Results. Unloaded, and thus almost lipofuscin-free, control cells exposed to latex beads showed numerous cytoplasmic particles emitting reddish fluorescence, while few particles were taken up by cells initially loaded with artificial, POS-derived, lipofuscin. Measurement of the latex bead-specific fluorescence showed significantly (p < 0.001) higher levels in unloaded control cells than in lipofuscin-loaded ones.In the second part of the investigation, unloaded control cultures and lipofuscin-loaded cultures were exposed to native bovine Texas Red-X-labelled POS 4 weeks after the establishment of the cultures. Unloaded control cells showed a large number of cytopiasmic POS emitting reddish fluorescence, while fewer POS were phagocytosed by cells loaded with artificial lipofuscin. Measurement of the Texas Red-X-specific fluorescence, thus quantifying the phagocytic ability of the cells, showed significantly (p < 0.001) higher levels in control cells than in lipofuscin-loaded ones.Conclusions. Severe lipofuscin accumulation of RPE cells appears to result in a greatly decreased phagocytic capacity. The resulting reduction in ability to cope with the needs of the overlying photoreceptor cells, in order to eliminate the obsolete tips of their POS, may well be of significance in the development of age-related macular degeneration.
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| 4. |
- Zhang, Hui, et al.
(författare)
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Increased catalase levels and hypoxanthine-enhanced nitro-blue tetrazolium staining in rat retina after ischemia followed by recirculation
- 1995
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Ingår i: Current Eye Research. - : Informa UK Limited. - 0271-3683 .- 1460-2202. ; 14:1, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, using retinal ischemia as a model, we examined if different periods of ischemia and recirculation influenced the generation of reactive oxygen species, i.e. in hydrogen peroxide generation and nitroblue tetrazolium (NBT) reduction. Ischemia was induced for 30 and 90 min by ligation of the optic nerve with the vessels and recirculation was established by removing the ligature. The rats were sacrificed after 15 min or 3 days of recirculation. The retinas were separated from the pigment epithelium for measurements of catalase activity and examination of NBT staining. Compared to controls, the catalase activity was increased after 30 and 90 min of ischemia followed by 15 min of recirculation, and after 90 min of ischemia followed by 3 days of recirculation. As in controls, NBT staining was observed, both after 30 and 90 min of ischemia followed by 15 min of recirculation, in photoreceptors, in both plexiform layers, in some ganglion and glial cells, and, occasionally, in cells in the inner nuclear layer. Opposite to controls, addition of hypoxanthine to the NBT solution resulted in an increased staining in vessels in the inner nuclear layer in retinas subjected to 30 min of ischemia followed by 3 days of recirculation. The increased catalase activity suggests an increased amount of this free radical scavenger after ischemia followed by short-term and long-term recirculation. The hypoxanthine-enhanced NBT staining of blood vessel walls after ischemia followed by long-term recirculation indicates an activation of xanthine oxidase and an increased production of NBT reductants, some of which may represent oxygen free radicals.
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