J Korean Ophthalmol Soc.  1998 Oct;39(10):2303-2312.

The Effects of N-Methyl_D-Aspartic Acid, and Antagonism by Kynurenic Acid on Neurons in the Cathish Retina

• Lee SJ
• Jung CS
• Bai SH

Abstract

To investigate the mechanism of the excitatory signal transmission, the effects of N-methyl-D-aspartate(NMDA, ionotropic glutamate agonist) and kynurenic acid(glutamate antagonist) on catfish retinal neurons were explored using conventional intracellular recording techniques. Horizontal cells were depolarized by glutamate, kainate, quisqualate, and NMDA but gyperpolarized by kynurenate. Transient components of both ON-and OFF-bipolar cells were reduced either by glutamate or by NMDA. Kynurenate suppressed sustained components of the third-order neurons or OFF-bipolar cells. Furthermore, kynurenate blocked the depolarizing actions of NMDA on horizontal cells and ON-sustained cells with large ON-transient components. The results suggest that NMDA would exert a tonic depolarization in the horizontal cells and the 3rd-order neurons, and there might be a preferential suppression on the a NMDA receptors by kynurenic acid in the catfish retina.

Keyword

Catfish retina; Glutamate; NMDA; APB; Kynurenate

MeSH Terms

Catfishes
Glutamic Acid
Kainic Acid
Kynurenic Acid*
N-Methylaspartate
Neurons*
Quisqualic Acid
Receptors, N-Methyl-D-Aspartate
Retina*
Retinal Neurons
Glutamic Acid
Kainic Acid
Kynurenic Acid
N-Methylaspartate
Quisqualic Acid
Receptors, N-Methyl-D-Aspartate