Presence of the binding of a variety of ligands related to ionotropic excitatory amino acid receptors in rat retina

Abstract

The binding of [ 3H] l-glutamic (Glu),[ 3H](±)-3-(2-car☐ypiperazin-4-yl)propyl-1-phosphonic and [ 3H] d,l-(E)-2-amino-4-propyl-5-phosphono-3-pentenoic acids was detected in rat retinal membranes extensively washed and treated with a low concentration of Triton X-100, in addition to the binding of both [ 3H]glycine (Gly) and [ 3H]5,7-dichlorokynurenic acid. Furthermore, retinal membranes exhibited the binding of[ 3H](+)-5-methyl-10,11-dihydro-5H-dibenzo[ a,d]cyclohepten-5,10-imine in the presence of Glu, Gly and spermidine irrespective of the incubation period employed. Rat retina also contained the binding of [ 3H]kainic acid as well as the binding of [ 3H]α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid which was sensitive to potentiation by potassium thiocyanate. In addition, the binding of both[ 3H](+)-3-(hydroxyphenyl)- N-(1-propyl)piperidine and [ 3H]1,3-di- o-tolyl-guanidine was found in rat retina membranes extensively washed but not treated with Triton X-100. These results give support for the proposal that the rodent retina contains subclasses of ionotropic brain excitatory amino acid receptors including the N-methyl- d-aspartate receptor ionophore complex as well as σ sites.