N-Acetylserotonin (NAS)/normelatonin acts as a precursor of melatonin in the tryptophan metabolic pathway.N-Acetyl-5-hydroxytryptamine has been used to treat neuron cells and to analyze its effects on Krüppel-like factor 15 (KLF15) expression.;N-Acetylserotonin (NAS)/normelatonin acts as a precursor of melatonin in the tryptophan metabolic pathway.N-Acetyl-5-hydroxytryptamine has been used to treat neuron cells and to analyze its effects on Krüppel-like factor 15 (KLF15) expression.