Kynurenic acid synthesis in bovine retinal slices--effect of glutamate agonists

• Published in: Journal of Neural Transmission Vol. 113; no. 10; pp. 1367 - 1372
• Main Authors: Zarnowski, T, Bialek, M, Rejdak, R, Zrenner, E, Junemann, A, Zagorski, Z, Kocki, T, Turski, W A
• Format: Journal Article
• Language: English
• Published: Austria Springer Nature B.V 01.10.2006
• Subjects: alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid - metabolism; Animals; Aspartic Acid - metabolism; Cattle; Excitatory Amino Acid Agonists - pharmacology; Glutamic Acid - metabolism; Kynurenic Acid - metabolism; N-Methylaspartate - metabolism; Organ Culture Techniques; Retina - drug effects; Retina - metabolism
• ISSN: 0300-9564; 1435-1463
• DOI: 10.1007/s00702-005-0423-0

The purpose of the present study was to investigate the effect of glutamate agonists upon kynurenic acid (KYNA) production in bovine retinal slices. Quantitative analysis of newly synthesized KYNA was carried out using an HPLC system and detected fluorimetrically. Glutamate at the concentration of 0.01, 0.1 and 1 mM reduced KYNA synthesis in the retinal slices to 70% (p < 0.05), 35% (p < 0.01) and 23% (p < 0.001), respectively. The concentration of glutamate reducing production of KYNA by 50% (IC(50)) was 0.035 mM (0.02-0.06). Aspartate at the concentration of 0.01, 0.1 and 1 mM lowered KYNA synthesis in the retinal slices to 80% (p < 0.01), 57% (p < 0.001) and 43% (p < 0.001), respectively. In contrast, kainic acid (up to 5 mM), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) (up to 1 mM) and 1-aminocyclopentane-trans-1,3-dicarboxylic acid (t-ACPD) (up to 3 mM) turned out to be ineffective in diminishing KYNA synthesis. These data demonstrate that glutamate, aspartate and N-methyl-D-aspartate (NMDA) inhibit KYNA synthesis in bovine retinal slices with different potency.