Figure 1
The monoamine neurotransmitter pathway. Abbreviations: GTP = guanosine triphosphate; GTPCH = guanosine triphosphate cyclohydrolase 1; PTPS = 6-pyruvoyltetrahydropterin synthase; SR = sepiapterin reductase; BH4 = tetrahydrobiopterin; TH = tyrosine hydroxylase; DHPR = dihydropteridine reductase; qBH2 = quinonoid dihydrobiopterin; 5-HTP = 5-hydroxytryptophan; L-dopa = levodihydroxyphenylalanine; PLP = pyridoxal phosphate; AADC = aromatic L-amino acid decarboxylase; 5-HIAA = 5-hydroxyindoleacetic acid; HVA = homovanillic acid; MHPG = 3-methoxy-4-hydroxylphenylglycol; VMA = vanillylmandelic acid.