Is there any common precursor chemical that

[tica]

results in the synthesis of the major neurotransmitters? For example, what is norepinephrine's precursor?

[know_it_all]

There is no universal precursor. The cathecholamines (dopamine, norepinephrine, and epinephrine) can each be made from tyrosine.Glutamate and GABA, however, come from glutmate, glutamine, glutamic acid, or even possibly alpha keto glutartate (the body can interconvert all of these compounds).Serotonin and Melatonin can be made from tryptophan.I am not sure about any of the other neurotransmitters, but as you can see these are some of the major transmitters, and they have completley different precursors.