[Proliferation of retinal glia and excitatory amino acids]

Kainic acid administered intravitreally induced mitogenic effects in the adult rat retina at doses ranging from 60 nm to 200 nm. Similar effects resulted from the injection of domoic acid at doses ranging from 20 nm to 400 nm, and ouabain. L-glutamate, N-methyl D-aspartate and quisqualate provoked similar cytotoxic effects, i.e., swelling and vasuolization of the outer plexiform, inner nuclear and inner plexiform layer, and cell pycnosis. The latter induced no mitoses. The use of Rompun ketamine as anesthetic blocked the mitogenic effects. The immunohistochemical labelling of both glial fibrillary acidic protein and S100 protein in the dividing cells and the location of dividing nuclei in the inner nuclear layer are arguments for their Müllerian nature. We suggest that the mitogenic effects could account for reactive gliosis observed in some clinical conditions.