The brains of neonate albino rats were examined with the light and electron microscope following subcutaneous administration of monosodium glutamate (MSG). In addition to lesions in areas known to be vulnerable to glutamate, such as the arcuate nucleus of the hypothalamus, distinct areas of necrotic tissue were detected in the granular portion of the retrosplenial cingulate cortex. The affected cells display the cytological features characteristic of MSG-lesioned brain tissue, including vacuolization of the endoplasmic reticulum and clumping of chromatin. Numerous pyknotic nuclei can be detected as early as 3 h following treatment. The possible causes of the lesion, particularly the role that may be played by astrocytes, are discussed.
Key words Cingulate cortex - Monosodium glutamate - Neurotoxic amino acid - Cell degeneration - Rat
This research was generously supported by a grant from the DFG (Me 559/4). The author wishes to express her deep gratitude to Dr. Pedro Mestres for his interest in the progress of this work. Thanks are due to Miss H. Jaeschke for technical assistance and to Mrs. J. Schäfer for typing the manuscript.