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Functional Assessment of Urinary Neuro-biogenic Amines—A COMPREHENSIVE GUIDE 


Types and Functions

of Neuro-biogenic Amines

There are many types of neuro-active

substances. “Classic” neurotransmitters

are called small molecule neurotrans-

mitters or biogenic amines. Some amino

acids obtained from the diet or synthe-

sized in the body may act as neurotrans-

mitters or neuromodulators. Other

amino acids serve as precursors for neu-

rotransmitter synthesis. Many peptides

(proteins formed by linked amino acids)

are neuro-active, and many hormones

have neuro-active properties. The neu-

rotransmitters tested by Doctor’s Data,

Inc. include precursor and neuro-active

amino acids, “classic” small molecule

neurotransmitters and their metabolites:

Small molecule neurotransmitters

(biogenic amines)

Catecholamines: Dopamine,

Epinephrine (Adrenalin),


Histamine, Serotonin


3,4-Dihydroxyphenylacetic acid

(DOPAC), 3-Methoxytyramine

(3-MT), 5-Hydroxyindolacetic

acid (5-HIAA), Metanephrine,


Trace Amines: Phenylethylamine

(PEA), Tyramine, Tryptamine

Amino acids

Gamma aminobutyric acid

(GABA), Glutamate, Glycine,

Taurine, Tyrosine

Neurotransmitter function is de-

termined by the molecule’s post-syn-

aptic effects. (See Figure 1.)

Neurotransmitters act in two ways, they

either increase (excitatory) or decrease

(inhibitory) the likelihood that a nerve

cell will transmit any electrical informa-

tion. Multiple neurotransmitters may be

released together into a single synapse.

The neurotransmitters released togeth-

er may serve as “co-transmitters”. As

co-transmitters they may further influ-

ence a nerve cell or receptor’s response

to neuro-active compounds. Excitatory

neurotransmitter synapses have a differ-

ent conformation (form) and location on

the nerve cell from inhibitory synapses.

Only two neurotransmitters, the amino

acids GABA and glycine, have inhibitory

effects. The levels of neurotransmitters

are determined by their rates of syn-

thesis and metabolism (breakdown), or

turnover. The effect of a neurotransmit-

ter is determined, in large part, by the

receptor that it binds to.