Abstract
1. Radioactivity and its distribution in the neonatal mouse brain following subcutaneous administration of ^<14>C-labeled monosodium glutamate (MSG) were studied by means of radiometry and freezing autoradiography. 2. The. brain level of radioactivity proportionally increased and peaked at 3 hours after the injection of radiolabeled MSG, then gradually decreased, whereas the blood level of radioactivity rapidly increased, peaking at 50 minutes, and rapidly decreased thereafter. 3. The radioactivity on the brain autoradiograph was less than in other head tissues, but marked accumulation of radioactivity was observed in the retina, lens, preoptic area, hippocampus, dorsal surface of thalamus, arcuate nuclear region, and choroid plexus of lateral and third ventricles at 15 minutes to 24 hours. These areas, except lens and choroid plexus, correspond to the sites of MSG-induced lesions.
