Existence of Ionotropic Glutamate Receptor Subtypes in Cultured Rat Retinal Ganglion Cells Obtained by the Magnetic Cell Sorter Method and Inhibitory Effects of 20-Hydroxyecdysone, a Neurosteroid, on the Glutamate Response

Abstract

ABSTRACT-Glutamate and neurosteroids are known to exist in retinal ganglion cells (RGC). Therefore, patch clamp studies using the whole-cell recording method were performed to determine whether or not ionotropic glutamate receptor subtypes, i.e., N-methyl-D-aspartate (NMDA), a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and kainate receptors, were present on RGC obtained by the magnetic cell sorter (MACS) method and cultures. In addition, the effects of 20-hydroxyecdysone (20-HE), a neurosteroid, on inward currents induced by NMDA, AMPA and kainate were examined at a holding potential of -60 mV. The current-voltage relationship for NMDA in the presence of glycine and Mg 2+ -free, as well as those for AMPA and kainate were linear, with a reversal potential of around 0 mV. NMDA-induced currents were blocked by MK-801, while both AMPA-and kainate-induced currents were blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Application of 20-HE in the bath resulted in significant inhibitions on NMDA-, AMPA-and kainate-induced currents. Thus, NMDA, AMPA and kainate receptors were confirmed to exist on MACS-separated cultured RGC. Moreover, 20-HE inhibited NMDA receptor-mediated currents most prominently and AMPA-and kainate-mediated currents moderately, suggesting that neurosteroids may be playing a role in modulating glutamate-mediated transmission in RGC, and 20-HE might be useful for preventing glutamate neurotoxicity.

TRPV1: Contribution to Retinal Ganglion Cell Apoptosis and Increased Intracellular Ca2+with Exposure to Hydrostatic Pressure

“…16,55–61 The P4–P10 developmental stage is particularly advantageous for the isolation of RGCs because the apoptotic elimination of excess RGCs during development is complete, and the remaining RGCs have a functional axon in the optic nerve with arborization of presynaptic terminals within the brain. 62–64 Furthermore, the relatively undifferentiated state of other neurons in the retina eases dissociation of the retina and specificity of antigen-based isolation.…”

A Computational Study on the Role of Gap Junctions and Rod Ih Conductance in the Enhancement of the Dynamic Range of the Retina

“…AMPA receptors are found in AII amacrine and ganglion cells [31], [32] and metabotropic mGluR6 receptors are found in bipolar cells [33]. These two receptor types were modeled by the same equations [30].…”

Effect of neurosteroids on the retinal gabaergic system and electroretinographic activity in the golden hamster

“…Alternatively, it was demonstrated that NSs can modulate glutamate‐mediated transmission in several systems, including retinal ganglion cells (Wu et al . 1991; Mukai et al . 2002).…”