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18

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

dexamethasone

diuretics

epinephrine

insulin

imipramine

lithium

methyldopa

monoamine oxidase (MAO)

inhibitors

nicotine

nitroglycerine

decongestant nose drops

propafenone

reserpine

salicylates (aspirin)

theophylline

tetracycline

tricyclic antidepressants

vasodilators

Medications that may alter serotonin

levels include:

morphine

monoamine oxidase (MAO)

inhibitors

reserpine

methyldopa

lithium

serotonin re-uptake inhibitors

tryptophan or 5-hydroxy tryptophan

(5-HTP) supplements

No medication should ever be dis-

continued without the permission of

the prescribing physician.

Sudden dis-

continuation of certain medications may

be hazardous to health.

Digestion and Absorption

The gastrointestinal tract (GIT) has

its own nervous system. The enteric

(GIT) nervous system is sometimes call

a “second brain”; fibers from the GIT

travel directly to the central nervous sys-

tem via the vagus nerve. Ninety percent

of the fibers in the vagus nerve originate

in the gut and travel

to

the brain. The va-

gus nerve is part of the autonomic (“vis-

ceral”) nervous system. The autonomic

nervous system regulates involuntary ac-

tivity such as digestion, blood pressure

and respiration. Disorders may originate

in the autonomic nervous system or re-

sult from another disease such as diabe-

tes or Parkinson’s disease. Altered neu-

rotransmitter levels may contribute to

autonomic enteric nervous system dis-

orders in the GIT. In addition to GIT-

specific neuro-active compounds, the

gastrointestinal tract responds to signals

from catecholamines (dopamine, epi-

nephrine, norepinephrine), serotonin

and melatonin. Mood disorders may

alter the levels of gastrointestinal hor-

mones, such as somatostatin and vasoac-

tive intestinal peptide (VIP). Alterations

in GIT hormone signaling may contrib-

ute to irritable bowel syndrome (IBS).

Peripheral dopamine and norepineph-

rine metabolism occurs primarily in the

gut. Sulfotransferase (SULT) 1A3 is one

of three metabolic pathways for dopa-

mine, and is found in the gastrointestinal

tract and colon. (See Figure 4.)

Urinary levels of neurotransmitters

primarily reflect the activity of the pe-

ripheral and GIT enteric nervous sys-

tems. Digestion, motility, immunity,

permeability and absorption of nutri-

ents may affect neurotransmitter syn-

thesis, or be affected by, alterations in

neurotransmitter levels or disorders of

the autonomic nervous system.

The gastrointestinal bacteria (micro-

biome) is known to synthesize and me-

tabolize both neuro-active compounds

and essential vitamins (biotin, Vitamin

K, etc.). A healthy microbiome may

contribute to neurotransmitter balance

through gut-brain-microbiome commu-

nications. A diet full of fresh fruits, vege-

tables, nuts, seeds, and legumes provides