A neuroactive metabolite of L-tryptophan potentiates acetylcholine-induced transient inward currents in Xenopus oocytes expressing a7 nAChRs potentiates 5-HT-induced ion currents in N1E-115 mouse neuroblastoma cells at 1 mM decreases gastrointestinal transit time in rats at 30 mg/kg induces convulsions in rats from 50 to 100 mg/kg serums levels are positively correlated with working memory in patients with schizophrenia