3H]- d-aspartate accumulation in the retina of pigeon, guinea-pig and rabbit

Abstract

Retinas from pigeons, guinea-pigs and rabbits were exposed to [ 3 H]- d -aspartate either by intraocular injections or by incubating undetached or detached retinas in it. In all species about 5–10% of the cells in the ganglion cell layer became radioactive. In the pigeon most of the photoreceptors became radioactive when the substance reached them (i.e. when the retina was detached) and, in guinea-pigs and rabbits, about 10% of them also became radioactive. In the latter case the radioactive photoreceptors were characterized by long myoids protruding out among the surrounding outer segments and by having their perikarya in the outermost cell row of the outer nuclear layer. The frequency distribution and morphology of the radioactive photoreceptors suggest they are cones. Since [ 3 H]- d -aspartate can be presumed to label neurons using aspartate or glutamate as transmitter, the work suggests that cones and about 5–10% of all ganglion cells use either of the two substances as transmitter.