Electrochemical und Immunohistological Detection of NO and NO-Synthase in the Rat Retina following Optic Nerve Axotomy
Groppe M., Naskar R., Heiduschka P., Thanos S.
Abteilung für Experimentelle Ophthalmologie, Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Münster
Purpose: The increased production of nitric oxide (NO) after optic nerve axotomy is associated with neuronal degeneration in the retina. Detailed knowledge of the extent and the time course of NO production is of great importance for the understanding of retinal ganglion cell (RGC) death and it's appropriate treatment. Therefore, NO-production was analysed electrochemically and the expression of NO-synthase (NOS) was examined after lesioning the optic nerve.
Method: Optic nerve axotomy induced degeneration of the RGC in Spraque-Dawley rats. At 2, 5, 9 and 14 days after the operation cryosections of the retina were stained with antibodies against the three isoforms of NOS. At the same time points whole mounts were prepared from the retinas. A platinum-disc electrode was polymerised with a NO-sensitive Ni-Porphyrin and Eugenol. For measurement of the NO-concentration in the retina differential pulse amperometry was used. Quantification of the RGC was performed by retrogradely labeling the cells with Di-Asp from the superior colliculus.
Results: An NO concentration of approximately 15 mM was measured in control retinas. Two and 5 days post axotomy the concentration was elevated up to 23 µM and decreased below the initial value after nine and fourteen days. No significant changes of NO
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