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

Lee, Sung Jong; Jung, Chnag Sub; Bai, Sun Ho

Original Article

Journal of the Korean Ophthalmological Society 1998;39(10):2303-2312.
Published online October 1, 1998.

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

Sung Jong Lee, Chnag Sub Jung, Sun Ho Bai

Physics & Biophysics Section, Department of Natural Sciences, College of Medicine, The Catholic University of Korea.

메기 망막의 신경원에 미치는 N-methyl-D-aspartic acid 의 효과와 Kynurenic acid 의 길항작용

이성종(Sung Jong Lee),정창섭(Chang Sub Jung),배선호(Sun Ho Bai)

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.

Key Words: Catfish retina;Glutamate;NMDA;APB;Kynurenate