The Toxic Effect of Sodium L-Glutamate on the Inner Layers of the Retina

L-Glutamic acid and its sodium salt have been widely used in the oral treatment of petit mal and mental deficiency (e. g., Zimmerman, Burgemeister, and Putnam, 1949; Milliken and Standen, 1951). Single doses of 20-30 gm. have also been administered intravenously without permanent illeffects (Sapirstein, 1943; Elman, 1946; Mayer-Gross and Walker, 1949; Weil-Malherbe, 1949). During an investigation of the influence of various substances of biochemical importance upon the progress in the mouse of an hereditary retinal dystrophy it was observed that the parenteral administration of sodium L-glutamate damaged the inner layers of the retina, which are not themselves involved in the genetic lesion. Since this lesion could also be produced in normal mice, a limited study was made of its histological development and the conditions necessary for its appearance in mouselings and adults of the Strong A2 (Glaxo) strain. Among substances related chemically or physiologically to glutamate, which were also