Evidence for intraocular synthesis of kynurenic acid, a putative endogenous neuroprotectant.
Kynurenic acid (KYNA), an excitatory amino acid antagonist preferentially active at glycine binding site of the NMDA receptor, has been previously identified in the brain. This study was designed to examine its presence in the rabbit vitreous humor. Mean (+/- SD) level of KYNA in the vitreous was 22.3 +/- 3.9 pmol/ml as determined by HPLC. Intravitreal administration of 10 mmol aminooxyacetic acid (AOAA), a KYNA synthesis inhibitor, diminished its production by 9.6% after 2 h, 47.8% after 24 h and 21.5% after 48 h. It can be concluded that AOAA decreases the intravitreal concentration of KYNA, providing evidence of its intraocular origin.
Department of Ophthalmology and 1st Eye Hospital, Medical University School, Lublin, Poland. zaro@panaceum.am.lublin.pl
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Zarnowski
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Rejdak
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Zagórski
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Kocki
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Kleinrok
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Turski
D000625:Aminooxyacetic Acid / Q000494:pharmacology; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000378:metabolism*; D007736:Kynurenic Acid / Q000378:metabolism*; D008190:Lyases; D008297:Male; D011817:Rabbits; D000637:Transaminases / Q000037:antagonists & inhibitors; D014822:Vitreous Body / Q000187:drug effects / Q000378:metabolism*
D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D000625:Aminooxyacetic Acid; D000637:Transaminases; C427605:glutamine - phenylpyruvate transaminase; C021481:kynurenine-oxoglutarate transaminase; D008190:Lyases; D007736:Kynurenic Acid