Monoamine neurotransmitters such as Catecholamines (dopamine, norepinephrine and epinephrine) and serotonin are the principle neurotransmitters that mediate a verity of CNS functions, motor control, cognition, emotion, memory processing and endocrine modulation. Catecholamines are synthesized by tyrosine hydroxylase (TH) using amino acid tyrosine and play an important role in a variety of functions such as endocrine regulation, cognition, emotions, memory processing and motor control [Kobayashi K (2001)]. Another important neurotransmitter, serotonin (5-HT) is synthesized by tryptophan hydroxylase (TPH1 and TPH2) by using amino acid tryptophan which influences learning, memory, mood states and perceptions of environment [Lovinger DM (1999)].
