Kynuramine: high affinity for [3H]tryptamine binding sites.

Kynuramine, an endogenously occurring metabolite of L-tryptophan, was found to displace [3H]tryptamine from its high affinity binding sites in rat brain cortex with an inhibition constant (Ki) of 28 nM. Kynuramine exhibited structural specificity and considerable selectivity, compared with its affinity for serotonergic, adrenergic and benzodiazepine recognition sites. This novel finding opens-up the possibility that kynuramine may exert physiological actions via the putative tryptamine receptor.