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A Takehara, H Gong, T Amemiya; Ultrastructural And Analytical Study In The Retina Of Copper-excessive Rats . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2615.
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Purpose:To examine the structure and elements in the retina of Cu-excessive rats with an electron microscope(TEM) and an energy dispersive X-ray analyzer (EDXA). Methods:Mature Wistar Kyoto rats were intraabdominally injected with 5mg/ml of CuCl2 /Kg body weight once a week for four weeks and control rats were injected with 1ml of distilled water/Kg body weight once a week. After four weeks the eyeballs were enucleated under pentobarbital anesthesia. Retinal specimens for element analysis were fixed in 4% glutaraldehyde with 0.05M cacodylate buffer for 1h, and then washed with 0.05M cacodylate buffer. Specimens for TEM were postfixed with 1% osmium tetroxide, while specimens for X-ray microanalysis were not postfixed. All specimens were dehydrated in a series of graded ethanols and embedded in Luveak 812. Ultrathin sections were cut and placed on nickel mesh. The sections were observed by TEM (JOEL JEM1210) and analyzed with an EDXA. Results:The mean serum Cu level was 172.3µg/dl in the Cu-excessive group and 116.0µg/dl in the control group. The Cu-excessive rats showed a decrease in number of cells in the inner nuclear layer. The inner nuclear layer nuclei showed clumps of chromatin and pyknosis. High density deposits existed in the retinal pigment epithelium. These deposits were analyzed with EDXA and found to contain iron, but not copper. Although rats treated with CuCl2 had the high serum Cu level, EDXA detected Fe, not Cu in the retinal pigment epithelium. TEM showed apoptotic changes in the inner nuclear layer, but not in other layers. Hypercupremia might induce iron accumulation due to hemolysis and lead to iron accumulation. The retinal changes in the present study might be due to iron accumulation, i.e. siderosis. Conclusion:Experimental hypercupremia might induce a secondary siderosis in the rat retina.
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