Neonatal excitotoxic brain injury. Physiologic, metabolic, and pathologic findings.

The mechanism of brain injury caused by excitotoxins has been explored in detail in the adult, but not the developing animal. To better define the cerebral physiologic. metabolic and pathological effects of excitotoxic damage, quisqualic acid (QA), a glutamate analogue, was injected into the parahippocampal region of the neonatal rat. Electroencephalographic monitoring showed intermittent paroxysmal discharges which persisted for more than 24 h. Metabolic alterations were consistent with disruption of membrane function with a decrease in n-acetyl aspartate and a rise in acetate. Neuropathologic examination disclosed neuronal necrosis which was maximal in the medial CA1 and hilar areas. QA produces a unique pattern of physiologic, metabolic, and pathologic alteration in the neonatal rat brain which differs from that produced by hypoxic-ischemic injury.