WHAT IS SEROTONIN x Neurotransmitter(神经递质) x Also called5 hydrotrptamine(5HT)5羟色胺 x Synthesized from tryptophanWHAT IS SEROTONIN?  Neurotransmitter(神经递质)  Also called 5-hydrotrptamine(5-HT)5-羟色胺  Synthesized from tryptphan