Metabolic scopes definitions

Two different methods have been used to determine the structure-activity relations of the neurotoxic action of the excitatory amino acids. With the first, the amino acids are administered by peripheral injection, which produces neuronal damage in areas of the brain to which the excitotoxins gain access. The second approach involves direct intracranial injection with analysis of the affected area to determine the scope and specificity of the lesion. While the latter method allows for more precise definition of toxic potencies and avoids variables such as metabolism and penetration of the blood-brain barrier, the systemic administration of these compounds was exploited first and continues to be used. 

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