Has anyone ever
told you how electrifying you are? Well, they may not be that far
from the truth! Every aspect of our being is interconnected by a communication
system compromised of neurons, synapses and chemicals (known as neurotransmitters)
that ignite a stimulating fire beneath us.
To understand
this fire, and to understand our bodies, we must study the chemical
transactions within them.
Neurotransmitters
are produced in the cell body of a neuron and are then stored in vesicles
until they move down the axon to the axon terminal. They are released
from their terminal when the vesicles join with the membrane of the
axon terminal. This process spills the neurotransmitters into a calcium
channel known as a synapse where they forge through and are accepted
by the receptor neuron. The following activity has the possibility
of being depolarized or hyperpolarized. A depolarized membrane would
stimulate postsynaptic activity whereas a hyperpolarized membrane
would restrain postsynaptic activity.
After the chemical
is released it must then be inactivated through one of four mechanisms.
Inactivation of
neurotransmitters can be done through diffusion, enzymatic
degradation, glial cells, or reuptake. Diffusion
is when the neurotransmitter drifts out of the synaptic cleft and
away from the receptor. When a specific enzyme alters the structure
of the neurotransmitter it will not be recognized by the receptor
and thus will not be utilized. This exemplifies enzymatic degradation
or deactivation. Glial cells are astrocytes that remove neurotransmitters
from the synaptic cleft, altering uptake. And reuptake is when the
entire neurotransmitter is taken back to the original axon terminal.
Otto Loewi,
an Austrian scientist, found the first neurotransmitter in 1921. He
utilized two frog hearts in which one remained connected to the vagus
nerve and was placed in a chamber of saline and the other was placed
in a connected chamber that allowed the fluid from the first chamber
to flow into the other as well. Electrical stimulation of the vagus
nerve slowed processes in both of the hearts with a slower reaction
time on the second heart. Loewi then hypothesized that stimulation
of the vagus nerve released a chemical into the first heart that then
flowed into the second heart. Today we know this chemical as acetylcholine.
Acetylcholine
is produced when choline is accepted by a receptor and choline
acetyltransferase is present. Choline thenreacts with acetyl coenzyme
A (CoA) to produce acetylcholine. It is synthesized in the central
nervous system and in peripheral parasympathetic nerve cells. Choline,
found in vitamins B1 and B5, is present in egg yolks, green leafy
vegetables and legumes. Acetylcholine aids with memory and musculature.
We have also seen decreased concentrations in the bodies of Alzheimer's
patients. Chemicals that block the proper function of acetylcholine
will dilate pupils and the respiratory system as well as decrease
muscle tone and mobility.
Acetylcholine
receptors can be nicotinic or muscarinic. Nicotinic
receptors are located in the brain, heart, adrenals and muscle tissue.
When acetylcholine binds to these sites, it increases the heart rate,
blood pressure and improves muscle tone. Nicotine, found in tobacco,
will bind to these receptors and will stimulate them. Forty-five
percent of smokers are mentally ill and this explains the craving
for tobacco products. An individual with a habit of smoking may be
lacking acetylcholine, thus when this neurotransmitter is replenished
and lobelia administered, this will inhibit the process, proving its
success in eliminating the habit of smoking.
Muscarinic
receptors are found in the brain, sweat glands and blood vessels.
Found to be essential in learning and retention, these
sites when stimulated also increase sweating, salivation, and body
temperature. Both of these sites are called cholinergic and they promote
the release and maintenance of acetylcholine.
A group of neurotransmitters
referred to as "catecholamines" contains dopamine,
norepinephrine and epinephrine. Norepinephrine and epinephrine, produced
by the adrenal gland, are respectively also referred to as
noradrenalin and adrenaline. These neurotransmitters are formed from
the amino acids phenylalanine and tyrosine. Catecholamines are responsible
for peripheral nervous system effects (elevated blood pressure and
blood sugar, muscular contraction and the release of TSH from the
pituitary) as well as central nervous system responses involving respiration
and psychomotor activity. They also control the flow of blood to the
skin, skeletal system and mucous membranes as well as heart and gastrointestinal
function. Norepinephrine and epinephrine influence metabolism by moderating
endocrine function and insulin release by the synthesis of glycogen
and fatty acid mobilization.
Andrenergic receptors
that usually accept norepinephrine or epinephrine can be inhibited
and stimulated by synthetic medicines such as Ritalin, cocaine, and
fenfluramine. Ephedrine, a Chinese herb, also binds to these receptor
sites. These sites are called Alpha Adrenergic Receptors and
Beta Adrenergic Receptors.
Alpha Adrenergic
Receptors decrease digestive activity while contracting the blood
vessels and the uterus. Beta Adrenergic Receptors contract the blood
vessels and the uterus muscles as well as stimulating the heart. "Beta
Blockers" are a common drug prescribed to inhibit the proper
function of this receptor. Lobelia will also inhibit this function.
Norepinephrine and epinephrine become inactivated by the action of
catecholamine-O-methyltransferase (COMT) and monoamine oxidase (MAO).
Monoamine oxidase is also known to break down serotonin, dopamine
and melatonin as well. Cases of depression have seen improvements
with the addition of MAO inhibitors (MAOI), discovered when tuberculosis
patients noticed an improvement in mood after being treated with isoniazid.
Herbs such as St. John's Wort, Ginkgo Biloba and Passion
Flower have proven the same benefit. St. John's Wort however does
not allow enzymatic activity to break down serotonin and Ginkgo helps
to prevent breakdown of the serotonin receptor sites as we age.
Drugs noted as
selective serotonin reuptake inhibitors (SSRIs), including Prozac,
Paxil, and Zoloft, block the reuptake of serotonin. Thus, SSRIs create
a false sense of detachment and the excess serotonin creates an elevation
of mood. Another popularized drug that has many of the same side effects
is Ritalin. These drugs are noted as stimulants and react quite similar
to the street drug 'speed'. Although drug companies list these drugs
as non-addictive, far too many former users have fought the increased
depression and weight gain due to withdrawal.
Dopamine,
responsible for sexual arousal and muscular coordination, is a neurotransmitter
that is deficient in Parkinson's sufferers. This is mainly because
of a decreased level of glutathione or and excess amount of iron.
This process synthesizes dopamine into free radicals and degenerates
the neurons that produce dopamine.
Serotonin
(5-Hydroxytryptamine, 5HT), derived from tryptophan, is found to be
in highest concentrations within the intestinal tract at 90%. The
remainder is found in platelets and the central nervous system. It
applies vasoconstriction to the cardiovascular, respiratory and intestinal
systems. Although most commonly associated with alleviating depression,
serotonin receptors have been found to control hunger, sleep, pain
response, seizure, and peristalsis as well as function of the limbic
system and brain.
Individuals with
a low serotonin level may notice cravings for carbohydrates. Being
that they are high in trytophan, ingesting these foods may increase
the body's production on serotonin. All too often these 'cravings'
are satisfied by refined or processed foods. It is much better to
assist the body by ingesting complex carbohydrates to ease the deficiency.
GABA (Gamma Amino Butyric Acid) is best known as an inhibitor
of presynaptic transmission, or it keeps the brain from being 'trigger
happy'. When in balance, GABA prevents anxiety and increases mental
clarity. Anxiolytic drugs of the benzodiazepine family (Valium, Xanax)
work off of the soothing effects of GABA receptor response. Herbs
found to bind to the GABA receptors are kava kava, hops
and lemon balm.
Glutamic Acid,
aiding in processing and retention of mental stimuli, is both a neurotransmitter
and an amino acid. Glutamine along with vitamin B6 is needed for the
production of this transmitter. Glutamic acid is also produced in
mass quantities during a stroke.
Glycine,
an inhibitory neurotransmitter, is found in the spinal cord and brain
stem. Glycine is an amino acid that acts as a neurotransmitter and
it has proven to be helpful in the treatment of epilepsy.
Histamine,
most commonly associated with allergies, has a different function
when involved in neurological activity. Histamine is shown to inflame
tissue, dilate capillaries and too increase permeation of tissue to
promote lymphatic movement throughout the system. Along with serotonin,
histamine is also effective in the release of enkephalins, pain relieving
chemicals.
Other neurotransmitters
that are less studied or newly discovered are endorphins, substance
P, and Nitric Acid. Endorphins elevate mood and ease pain.
The receptor sites associated with these transmitters are called opiate
receptors. Substance P is found within the brain as well as sensory
neurons. It is meant to signal pain, yet opiates and capsaicin (capsicum)
tend to ease the intensity of such pain by inhibiting the supply of
substance P to the synapses. Nitric Acid, recently discovered, sends
messages to various organs including the colon. It has many functions
such as erectile function, lowering of blood pressure, formation of
synaptic junctions and it also inhibits bacterial growth. It is formed
from the amino acid arginine, which then creates the enzyme called
nitric oxide synthease (NOS). NOS interacts with guanlate cyclase
and synthesizes into cyclic GMP.
Originally created
as a cardiovascular drug, Viagra works by stopping the degrading of
cyclic GMP. It seems as if the 'side effect' seems to be its selling
point.
Although Viagra
has put the fire in many people, it is the neurotransmitters that
get to do the work. The complex firework display going on within our
bodies needs to be nurtured and tended to so that we don't burn ourselves
out. Although complex, with the aid of proper nutrients we should
be able to sit back and enjoy the beautiful display of wellness as
it crescendos into a long and healthy existence.
