Facilitatory and neurotoxic effects of intravitreal ornithine on the electroretinographic responses of albino rats.
The effect of an intravitreal injection of ornithine on the retina of rats was studied electroretinographically. Rats were injected intravitreally with 5 microl of 0.02, 0.25 and 0.5 M ornithine. Electroretinograms (ERGs) were recorded before, and 1, 3 and 9 days after the injection. High doses of ornithine (0.5 M) reduced while low doses (0.02 M) enhanced the ERG amplitudes. The implicit time of the a-wave was delayed at all concentrations after ornithine injection, which suggests that implicit times may be a more sensitive parameter of the ornithine effect. There were significant changes in the stimulus intensity necessary to obtain the one half of the maximum amplitude of the b-wave that may have been caused by damage of the photoreceptors and retinal pigment epithelium cells by ornithine. We conclude that the effect of ornithine on retinal function is dose dependent and can either enhance or depress the ERG amplitudes.
Department of Ophthalmology, Chiba University School of Medicine, Chiba, Japan. mizota@ophthalm.m.chiba-u.ac.jp
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Mizota
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Sato
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Adachi-Usami
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004596:Electroretinography / Q000187:drug effects*; D005260:Female; D007267:Injections; D009952:Ornithine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000187:drug effects* / Q000502:physiology; D014822:Vitreous Body
D009952:Ornithine