Endogenous excitotoxins

A potential for endogenous excitotoxin produced in the CNS via tryptophan metabolism has been localised to microglia.97 Microglia contain indoleamine-2,3-dioxy-genase (the first enzyme in this pathway), which converts tryptophan to kynurenine, and which is induced in microglia and macrophages by IL-1 and infections.98 Inhibitors of quinolinic acid production such as 4-chloro-3-hydroxyanthranilate and ///-nitrobenzylalanine99 100 could probably be of therapeutic value. 

Olney, J.W., Zorumski, C., Price, M.T. and Labruyere, J. (1990a). L-Cysteine, a bicarbonate sensitive endogenous excitotoxin. Science 248 596-599. 

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