The Nervous System: Neurons
Nervous and Endocrine systems
The nervous and endocrine systems work together to coordinate the actions of all other systems
of the body to produce behavior and maintain homeostasis.
The endocrine system produces chemical messengers that are transported through the circulatory
system. It requires seconds, minutes or hours.
The nervous system is more rapid, requiring only thousandths of a second.
Embryonic development
The nervous system originates from ectodermal tissue during embryonic development.
Neurons
Neurons are cells that transfer stimuli to other cells.
Structure of Neurons
Cell Body - contains nucleus and organelles
Dendrites - receive input
Axon - conducts impulses away from the cell body
Axon hillock - an enlarged region where an axon attaches to the cell body
Synaptic terminal - Neurotransmitters are manufactured in the cell body but released from
synaptic terminals. The neurotransmitters stimulate other neurons.
Synapse - A synapse is the junction between the synaptic terminal and another cell. The other
cell is called a postsynaptic cell.
Nerves and Ganglia
Axons and dendrites are bundled with axons or dendrites from other neurons to form nerves.
Clusters of neuron cell bodies are called ganglia.
Central and Peripheral Nervous Systems
The nervous system can be divided into the central nervous system (CNS) which includes the
brain and spinal cord and the peripheral nervous system (PNS) which includes everything else.
Classes of Neurons
Sensory neurons (afferent neurons) conduct sensory information toward the CNS. Sensory
neurons have a long dendrite and a short axon.
The brain and spinal cord contain interneurons. These receive information and if they are
sufficiently stimulated, they stimulate other neurons.
Motor neurons (efferent neurons) send information from interneurons to muscle or gland cells
(effectors).
Neuroglia
Neuroglia (also called glia) are cells within the nervous system that are not neurons.
There are different kinds of neuroglia, and they provide neurons with insulation, physical
support, metabolic assistance, and protection.
Myelination
Some neuroglia function to provide insulation for axons or dentrites. They do so by wrapping
around the long fibers.
The insulation properties come from myelin contained within the cells.
The layer of insulation is referred to as a myelin sheath.
If these insulating cells are located in the peripheral nervous system, they are called Schwann
cells.
Terms that are used to describe structures found in both the CNS and PNS
You will be responsible for learning the terms listed under PNS in the table below. Be aware that
these structures have a different name if they are located within the CNS.
Peripheral Nervous
System (PNS)
Central Nervous
System (CNS)
nerves
tracts
ganglia
nuclei
Schwann cells
oligodendrocytes
Membrane Potentials
Membrane potentials were first demonstrated using the giant axons of a squid (1mm dia). An
oscilloscope measured the electrical difference by placing one electrode outside the neuron and
the other inside the neuron.
Resting potential
The sodium-potassium pump pumps out 3 sodium ions (Na+) for each 2 potassium ions (K+)
pumped into the neuron. This results in more potassium ions inside and more sodium ions on the
outside.
Unequal pumping (3 Na+ out to 2K+ in) results in more positive charge on the outside compared
to the inside. The membrane is polarized.
Some K+ channels are open so K+ tends to leak out. This contributes to the negative charge
inside. The charge difference prevents further leakage.
The charge difference is measured in millivolts.
Gated Channels
The membrane contains channels that open or close, allowing the polarity of the membrane to
change as ions pass through the channel.
Ligand-gated channels are found in the synapses on postsynaptic cells. They open when bound
to specific ligands (molecules or ions) such as specific neurotransmitters.
Voltage-gated channels open when the membrane becomes depolarized. For example, sodium
gates open and then close slowly when the membrane is depolarized but remain closed when it is
polarized. When the sodium channel is open, sodium can pass through.
In a resting (polarized) neuron, sodium gates are closed. A slight depolarization will not cause
the gates to open but if the depolarization is greater than a threshold value, the gates will open.
Graded Potentials
Stimulation of a neuron causes sodium gates to open and the membrane becomes partially
depolarized as sodium ions enter the neuron. This type of depolarization is called "graded"
because the amount of depolarization depends on the strength of the stimulus. In the discussion
on action potentials below, we will see that conduction of a signal along a neuron is due to
depolarization that is independent of the strength of the stimulus.
Propagation of an Action Potential
As mentioned earlier, stimulation of the neuron causes Na+ gates open allowing Na+ to rush in.
This results in depolarization of the membrane in the area where the stimulation occurred. If the
depolarization is sufficient, it will depolarize adjacent areas of membrane causing more Na+
gates to open, thus spreading the depolarization.
Immediately after depolarization, Na+ channels close and K+ channels open causing K+ to flow
out. This process returns positive charge to the area just outside the membrane, thus restoring the
resting polarity.
The depolarization and repolarization events described above are called an action potential.
During an action potential, the depolarization spreads to neighboring areas of the neuron,
regenerating the action potential. Depolarization continues to spread all the way to the action
terminal where the axon joins another cell.
Action potentials are "all or nothing." The intensity of an action potentials does not diminish as
depolarization spreads along an axon.
Action potentials are initiated when depolarization reaches a threshold level. In typical
mammalian neurons, a depolarization to -55 mV produces an action potential.
The sodium-potassium pump operates continuously to restore the ionic gradient.
In the diagram below, depolarization caused by the influx of sodium can be seen spreading to the
right.
Refractory Period
The action potential cannot reverse its direction because membrane that has just been
depolarized cannot be depolarized again until after a brief recovery (called refractory) period.
During this period, the membrane is insensitive to stimulation.
The diagram below shows the voltage difference across the membrane during an action potential.
Initially, the inside of the membrane is approximately -65 or -70 millivolts compared to the
outside. When sodium gates open and sodium ions rush in, the inside temporarily becomes
positively charged. Potassium gates then open and potassium ions rush out, restoring the
negative charge.
Most action potentials last a few milliseconds and there may be as many as several hundred
action potentials per second.
Saltatory Conduction and Neuron Diameter
The gap between the Schwann cells in the myelin sheath is called a node of Ranvier. Gated
channels are concentrated in this area and not in the area under the myelin sheath. Action
potentials are regenerated at the nodes but not in the area underneath the myelin sheath. The
result is that the depolarization events spread farther, increasing the speed at which they spread.
The action potential spreads from node to node (saltatory conduction) causing it to spread faster.
Sodium-potassium pumps require a substantial amount of energy to pump the ions, so the
presence of insulation reduces the amount of membrane that requires active sodium-potassium
pumps, thus saving energy.
The diameter of the neuron also is related to the speed of conduction. Larger diameter axons
conduct faster. Example: squid axons are 500 microns dia.
Synaptic Potentials
Synapses
A synapse is a junction between a neuron and another cell. It is separated by a synaptic cleft.
In most synapses, the axon terminal of the presynaptic cell contains numerous synaptic vesicles
with neurotransmitter stored within them.
The action potential causes calcium channels to open in the plasma membrane of the presynaptic
cell. The calcium ions (Ca++) diffuse into the neuron and activate enzymes, which in turn,
promote fusion of the neurotransmitter vesicles with the plasma membrane. This process releases
neurotransmitter into the synaptic cleft.
Neurotransmitter molecules diffuse across the cleft and stimulate the postsynaptic cell, causing
Na+ channels to open and depolarization of the postsynaptic cell.
The depolarization of the postsynaptic cell is referred to as a synaptic potential.
The magnitude of a synaptic potential depends on:
the amount of neurotransmitter
the electrical state of the postsynaptic cell. If it is already partially depolarized, an action
potential can be produced with less stimulation by neurotransmitters. If it is hyperpolarized, it
will require more stimulation than normal to produce an action potential.
After the neurotransmitter is released into the synaptic cleft, it must be quickly removed or
inactivated to prevent the postsynaptic cell from being continuously stimulated and to allow
another synaptic potential.
In some cases there may be enzymes present in the synaptic cleft that break down the
neurotransmitter immediately. For example, acetylcholinesterase breaks down the
neurotransmitter acetylcholine.
In other cases, the axon terminal may reabsorb neurotransmitter and repackage it into vesicles for
reuse.
Excitatory and inhibitory postsynaptic potentials
A synaptic potential can be excitatory (they depolarize) or inhibitory (they polarize). Some
neurotransmitters depolarize and others polarize.
There are more than 50 different neurotransmitters.
In the brain and spinal cord, hundreds of excitatory potentials may be needed before a
postsynaptic cell responds with an action potential.
Synaptic integration
Synaptic integration is the combining of excitatory and inhibitory signals acting on adjacent
membrane regions of a neuron.
In order for an action potential to occur, the sum of excitatory and inhibitory postsynaptic
potentials must be greater than a threshold value.
Temporal and Spatial Summation
The effect of more than one synaptic potential arriving at a neuron is additive if the time span
between the stimuli is short. This is called temporal summation. The summation effect is
greatest when the time interval between stimuli is very short.
The effect of more than one synaptic potential arriving at a given region of a neuron can also be
additive. This is called spatial summation. The summing effect is greater if multiple stimuli all
arrive at nearby areas of a membrane. The effect is less if they stimulate separate, distant areas.
MAYBE AN EXAMPLE HERE ON TOUCH AND ADAPTATION
How do Nerve Impulses Start? [back to top]
We and other animals have several types of receptors of mechanical stimuli. Each initiates nerve
impulses in sensory neurons when it is physically deformed by an outside force such as:

touch

pressure

stretching

sound waves

motion
Mechanoreceptors enable us to

detect touch

monitor the position of our muscles, bones, and joints - the sense of proprioception

detect sounds and the motion of the body.
E.g. Touch
Light touch is detected by receptors in the skin. These are often found close to a hair follicle so even if the
skin is not touched directly, movement of the hair is detected.
In the mouse, light movement of hair triggers a generator potential in mechanically-gated sodium
channels in a neuron located next to the hair follicle. This potential opens voltage-gated sodium
channels and if it reaches threshold, triggers an action potential in the neuron.
Touch receptors are not distributed evenly over the body. The fingertips and tongue may have as many
as 100 per cm2; the back of the hand fewer than 10 per cm 2. This can be demonstrated with the twopoint threshold test. With a pair of dividers like those used in mechanical drawing, determine (in a
blindfolded subject) the minimum separation of the points that produces two separate touch sensations.
The ability to discriminate the two points is far better on the fingertips than on, say, the small of the back.
The density of touch receptors is also reflected in the amount of somatosensory cortex in the brain
assigned to that region of the body.
Proprioception

Proprioception is our "body sense".

It enables us to unconsciously monitor the position of our body.

It depends on receptors in the muscles, tendons, and joints.

If you have ever tried to walk after one of your legs has "gone to sleep", you will have some
appreciation of how difficult coordinated
muscular activity would be without
proprioception.
The Pacinian Corpuscle
Pacinian corpuscles are pressure receptors.
They are located in the skin and also in various
internal organs. Each is connected to a sensory
neuron. Pacinian corpuscles are fast-conducting,
bulb-shaped receptors located deep in the
dermis. They consist of the ending of a single
neurone surrounded by lamellae. They are the
largest of the skin's receptors and are believed to
provide instant information about how and where
we move. They are also sensitive to vibration. Pacinian corpuscles are also located in joints and tendons
and in tissue that lines organs and blood vessels.
Pressure on the skin changed the shape of the Pacinian corpuscle. This changes the shape of the
pressure sensitive sodium channels in the membrane, making them open. Sodium ions diffuse in
through the channels leading to depolarisation called a generator potential. The greater the pressure the
more sodium channels open and the larger the generator potential. If a threshold value is reached, an
action potential occurs and nerve impulses travel along the sensory neurone. The frequency of the
impulse is related to the intensity of the stimulus.
Adaptation
When pressure is first applied to the corpuscle, it initiates a volley of impulses in its sensory neuron.
However, with continuous pressure, the frequency of action potentials decreases quickly and soon
stops. This is the phenomenon of adaptation.
Adaptation occurs in most sense receptors. It is useful because it prevents the nervous system from
being bombarded with information about insignificant matters like the touch and pressure of our clothing.
Stimuli represent changes in the environment. If there is no change, the sense receptors soon adapt. But
note that if we quickly remove the pressure from an adapted Pacinian corpuscle, a fresh volley of
impulses will be generated.
The speed of adaptation varies among different kinds of receptors. Receptors involved in proprioception such as spindle fibres - adapt slowly if at all.
SOME EXPLANANTIONS ON WHAT COULD GO WRONG
The action can be decreased or neutralized in a number of ways including: glial cells, which
remove neurotransmitters from the synaptic cleft; reuptake, where the chemical is taken
back to the axon that released it; blocking, whereby the flow by substances that attach to
specific receptors is blocked; and by prolonged exposure to the neurotransmitter.
Common Neurotransmitters - KEY
Neurotransmitter
Function
Examples of
Malfunctions
Acetylcholine (Ach)
Enables Muscle Action
(movement), Learning,
Memory
Alzheimer’s disease: too little effects
memory, Ach-producing neurons
deteriorate in hippocampus deteriorate
causing memory problems
Excitatory
Botulism poison blocks Ach leads to
paralyze of respiratory muscles
Black Widow bite – too much - muscles
in violent convulsions
Dopamine
Influences movement, learning,
attention, and emotion
Excess dopamine receptor activity
linked to schizophrenia (positive
symptoms)
Movement and reward
Inhibitory
Strongly associated with
reward mechanisms in brain
Starved of dopamine, the brain
produces tremors and decreased
mobility of Parkinson’s disease
Play part of rewarding property
in drugs like cocaine, alcohol,
opium, heroin, nicotine…
THESE INCREASE
DOPAMINE
Serotonin
Inhibitory
Affects mood, hunger, sleep,
and arousal, impulsivity
Undersupply – linked OCD, anxiety,
mood disorders(depression), anger
control, insomnia, and suicide
Prozac and other antidepressant
increase serotonin levels
Drink warm milk at night – help you
sleep because contains and amino acid
that brain uses to make serotonin
(relax)
Plays a role in schizophrenia, may
interact with dopamine system to alter
the way it operates.
*Role in perception: LSD attaches to
serotonin receptor cites blocking
perceptual paths
Norepinephrine
Helps control alertness and
arousal
Mood, sleep, learning
Excitatory
Aka Noradrenaline
Undersupply can depress mood
Oversupply – insomnia
Increases heart rate and slows
digestion during stress
COULD MAKE AN ACTIVITY OUT OF THIS
Common Neurotransmitters - KEY
Neurotransmitter
GABA (gammaaminobutyric acid)
Inhibitory
Function
Examples of
Malfunctions
A major (best known) inhibitory
neurotransmitter
Undersupply linked to seizures,
tremors, and insomnia
Sleep; movement
Anxiety, Huntington’s disease,
epilepsy
Seems needed to keep neuron
activity in check
Too little GABA also may be anxiety
drugs –
Valium works by enhancing effects of
GABA
Too little GABA in some brain areas
can be epilepsy
Glutamate
Major excitatory
neurotransmitter
Excitatory
Oversupply – over stimulate brain
leading to migraines or seizures (why
some avoid MSG, monosodium
glutamate, in food)
Involved in memory
Damage after stroke
Most common in CNS – as
much as ½ of all brain neurons
Curiously…Actually toxic to
neurons and an excess will kill
them
Sometimes brain damage or stroke
leads to excess and many more brain
cells die than from original trauma
ALS – (Lou Gehrig’s Disease)
excessive glutamate production.
Schizophrenia – lack of glutamate
production. (negative symptoms)
Many neurologists feel this is
responsible for many CNS diseases
Endorphins
Released in response to pain or
vigorous exercise
(endogenous (produced
within) morphine)
If brain is flooded with opiates like
heroin and morphine the brain may
stop producing these natural opiates
Pain control
Lack of – no established disorder
Short for Endogenous
morphine – built in
morphine
Structurally similar to heroin and
has similar functions: pain
reduction, pleasure
Opiods work by attaching at
endorphin receptor site…
AGONISTS
This is the neurotransmitter
responsible for allowing bears and
other animals to hibernate. Heroin
slows heart rate, respiration, and
metabolism in general… exactly what
you need to hibernate… if you were a
bear. Heroin can slow it to nothing…
death or Permanent Hibernation
Neurotransmitters and their Functions
Neurotransmitters are the chemicals that facilitate the transmission of nerve impulses across the synapse. Some of
the important neurotransmitters and their functions are discussed in this article.
The transmission of signals from one neuron to another, across the synapse was earlier thought to be electrical.
Synapse is a small gap or junction between two neurons or a neuron and a muscle. In 1921, it was confirmed that
neurons actually communicate by releasing certain chemicals. The communication takes place through a change in
chemical concentration and these chemicals are called neurotransmitters. The credit for confirming this fact and
also for discovering the neurotransmitter, acetylcholine goes to the German pharmacologist, Otto Loewi. So,
neurotransmitters are the chemicals that allow the nerve impulses or signals to be transmitted across the synapse.
There are several types of neurotransmitters and each one of them is responsible for some specific functions. Given
below is some more information about the types of neurotransmitters and their functions.
Types of Neurotransmitters
There are a number of neurotransmitters, which can be classified in many different ways. But, more commonly
they are classified into three categories - amino acids, monoamines and peptides. Neurotransmitters like
glutamate, aspartate, glycine, serine and gamma aminobutyric acid (GABA) fall into the category of amino acids.
On the other hand dopamine neurotransmitter, serotonin, melatonin, epinephrine and norepinephrine are the
monoamine neurotransmitters. Calcitonin, glucagon, vasopressin, oxytocin and beta-endorphin are some of the
neuroactive peptides. There are about 50 neuroactive peptides till now, with new ones being discovered regularly.
Apart from these, acetylcholine, adenosine and nitric oxide are some other noteworthy neurotransmitters. Out of
all these neurotransmitters, we are going to discuss about the most well-known and important neurotransmitters
and their functions.
Neurotransmitters and Their Functions
Acetylcholine, dopamine, GABA, serotonin, epinephrine, norepinephrine and endorphins are the most significant or
crucial neurotransmitters found in the human body. The functions of these neurotransmitters are explained below.
Acetylcholine
It is the first neurotransmitter to be discovered in the year 1921. This neurotransmitter is responsible for
stimulating muscles. It activates the motor neurons that control the skeletal muscles. It is also concerned with
regulating the activities in certain areas of the brain, which are associated with attention, arousal, learning and
memory. People with Alzheimer's disease are usually found to have a substantially low level of acetylcholine.
Dopamine
Dopamine is the neurotransmitter that controls voluntary movements of the body and is associated with the reward
mechanism of the brain. In other words, dopamine regulates the pleasurable emotions, and drugs like cocaine,
heroine, nicotine, opium and even alcohol increase the level of this neurotransmitter, for which the user of such
drugs feels good. Decreased level of dopamine is associated with Parkinson's disease, while the patients of
schizophrenia are usually found to have excess dopamine in the frontal lobes of the brain.
Serotonin
Serotonin is an important inhibitory neurotransmitter, which has been found to have a significant effect on
emotion, mood and anxiety. It is also involved in regulating sleep, wakefulness and eating. A significantly low
serotonin level is found to be associated with conditions like depression, suicidal thoughts and obsessive
compulsive disorder. Many antidepressant drugs work by affecting the level of this neurotransmitter.
Gamma Aminobutyric Acid (GABA)
GABA is an inhibitory neurotransmitter that slows down neuron activity in order to prevent their over excitation,
which could lead to anxiety. GABA is a non-essential amino acid, that is produced by the body from glutamic acid.
A low level of GABA can have an association with anxiety disorders. Alcohol and drugs like barbiturates can
influence GABA receptors.
Glutamate
Glutamate is an excitatory neurotransmitter. It is the most commonly found neurotransmitter in the central
nervous system. Glutamate is mainly related with functions like learning and memory. An excess of glutamate is
however toxic for the neurons. An excessive glutamate production may be related with the disease, known as
amyotrophic lateral sclerosis (ALS) or Lou Gehrig's disease.
Epinephrine and Norepinephrine
Epinephrine is an excitatory neurotransmitter, that is derived from norepinephrine. Epinephrine controls mental
focus and attention. Norepinephrine is also an excitatory neurotransmitter and it regulates mood and both physical
and mental arousal. Increased secretion of norepinephrine raises the heart rate and blood pressure.
Endorphins
Endorphins are the neurotransmitters that resemble the opioid compounds like opium, morphine and heroine in
structure. In fact, their effect on the body is also similar to the effect produced by the opioid compounds. Like
opioids, endorphins can reduce pain, stress and promote calmness and serenity. These are the neurotransmitters
that enable some animals to hibernate by slowing down metabolism, respiration and heart rate.
So, these were some of the most common and well known neurotransmitters and their functions. Hope this article
provided some interesting facts about the neurotransmitters that allow the nerves to communicate with each other
and thus, regulate the various functions of the body.
By Chandramita Bora
Published: 6/30/2010
Important Neurotransmitters and their Function
Excerpts from "Mapping the Mind", Rita Carter
Different types of cells secrete different neurotransmitters. Each brain
chemical works in widely spread but fairly specific brain locations and may
have a different effect according to where it is activated. All of the major
neurotransmitters are made from amino acids except acetycholine. Some 60
neurotransmitters have been identified, but the most important, listed top to
bottom, seem to be:
Controls arousal levels in many parts of the brain and is vital
for giving physical motivation. When levels are severely
depleted, as in Parkinson's disease, people may find it
Dopamine impossible to move forward voluntarily. Low dopamine may
also be implicated in mental stasis. LSD and other
hallucinogenic drugs are thought to work on the dopamine
system.
This is the neurotransmitter enhanced by Prozac, and has thus
become known as the 'feel-good' chemical. It has a profound
Serotonin
effect on mood and anxiety -- high levels of it, or sensitivity
to it, are associated with serenity and optimism.
Controls activity in brain areas connected with attention,
learning and memory. People with Alzheimer's disease
Acetylcholine
typically have low levels of ACh in the cerebral cortex, and
(ACh)
drugs that boost its action may improve memory in such
patients.
Mainly an excitatory chemical that induces physical and
mental arousal and elevated mood. Production is centered in
Noradrenaline
an area of the brain called the locus coreuleus, which is one
of several putative candidates for the brain's 'pleasure' centre.
The brain's major excitatory neurotransmitter, vital for
Glutamate forging the links between neurons that are the basis of
learning and long-term memory.
These are opioids that, like the drugs heroine and morphine,
Enkephalins and modulate pain, reduce stress and promote a sensation of
Endorphins
floaty, oceanic calm. They also depress physical functions
like breathing and may produce physical dependence.
Excerpts from
"Mapping the Mind", Rita Carter
Weidenfeld & Nicolson, 1998
Neurological Control
Neurotransmitters
Neurotransmitter Molecules
More information on:
Neurotransmission at a
synapse
neurotransmitters can be broadly split into two groups – the
‘classical’, small molecule neurotransmitters and the relatively
larger neuropeptide neurotransmitters. Within the category of small molecule neurotransmitters,
the biogenic amines (dopamine, noradrenaline, serotonin and histamine) are often referred to as a
discrete group because of their similarity in terms of their chemical properties.
Small molecule neurotransmitters
Type
Neurotransmitter
Acetylcholine
Amino acids
Excitatory
Gamma aminobutyric acidGABA
Inhibitory
Glycine
Inhibitory
Glutamate
Aspartate
Biogenic amines
Postsynaptic effect
Dopamine
Excitatory
Excitatory
Excitatory
Noradrenaline
Excitatory
Serotonin
Excitatory
Histamine
Excitatory
Click on the links in the table above to read more about some of the important neurotransmitters.
Neuropeptide neurotransmitters
Corticotropin releasing hormone
Corticotropin (ACTH)
Beta-endorphin
Substance P
Neurotensin
Somatostatin
Bradykinin
Vasopressin
Angiotensin II
Serotonin
Although the CNS contains less than 2% of the total serotonin in the body, serotonin plays a very
important role in a range of brain functions. It is synthesised from the amino acid tryptophan.
Within the brain, serotonin is localised mainly in nerve pathways emerging from the raphe
nuclei, a group of nuclei at the centre of the reticular formation in the
Midbrain , pons and medulla. These serotonergic pathways spread extensively throughout the
brainstem , the cerebral cortex and the spinal cord . In addition to mood control, serotonin
has been linked with a wide variety of functions, including the regulation of sleep, pain
perception, body temperature, blood pressure and hormonal activity.
Outside the brain, serotonin exerts a number of important effects, particularly involving the
gastrointestinal and cardiovascular systems.
Noradrenaline
Noradrenaline is classed as a monoamine neurotransmitter and noradrenergic neurons are
found in the locus coeruleus , the pons and the reticular formation in the brain. These neurons
provide projections to the cortex, hippocampus , thalamus and midbrain. The release of
noradrenaline tends to increase the level of excitatory activity within the brain, and noradrenergic
pathways are thought to be particularly involved in the control of functions such as attention and
arousal.
Outside the brain, noradrenaline plays an important role in the sympathetic nervous system – the
system that co-ordinates the ‘fight or flight’ response. Systemically, therefore, changes in
noradrenergic activity may induce changes in a range of functions including heart rate, blood
pressure and gastrointestinal activity. This explains the broad side-effect profile associated with
drugs that affect monoamine neurotransmitters, such as the tricyclic antidepressants.
Find out more about noradrenaline and serotonin
Dopamine
Dopamine is also classed as a monoamine neurotransmitter and is concentrated in very specific
groups of neurons collectively called the basal ganglia. Dopaminergic neurons are widely
distributed throughout the brain in three important dopamine systems (pathways): the
nigrostriatal, mesocorticolimbic, and the tuberohypophyseal pathways. A decreased brain
dopamine concentration is a contributing factor in Parkinson’s disease, while an increase in
dopamine concentration has a role in the development of schizophrenia.
Acetylcholine
Acetylcholine ‘acts’ or ‘is transmitted’ within cholinergic pathways that are concentrated mainly
in specific regions of the brainstem and are thought to be involved in cognitive functions,
especially memory. Severe damage to these pathways is the probable cause of Alzheimer’s
disease.
Outside the brain, acetylcholine is the main neurotransmitter in the parasympathetic nervous
system – the system that controls functions such as heart rate, digestion, secretion of saliva and
bladder function. Drugs that affect cholinergic activity produce changes in these body functions.
Some antidepressants act by blocking cholinergic receptors and this anticholinergic activity is an
important cause of side effects such as dry mouth.
Neurotransmitters Receptors
Neurotransmitters exert their effect by binding to specific receptors on the neuronal postsynaptic
membrane. A neurotransmitter can either ‘excite’ its neighbouring neuron so increasing its
activity, or ‘inhibit’ its neighbouring neuron, suppressing its activity. In general, the activity of a
neuron depends on the balance between the number of excitatory and inhibitory processes
affecting it, and these can occur simultaneously. Most neurotransmitter receptors can be divided
into two types – ligand-gated receptors and G-protein linked receptors.
Stimulation of a ligand-gated receptor enables a channel in the receptor to open and permits the
influx of chloride and potassium ions into the cell. The positive or negative charges that enter the
cell either excite or inhibit the neuron. Ligands for these receptors include excitatory
neurotransmitters, such as glutamate and, to a lesser extent, aspartate. Binding of these ligands to
the receptor produces an excitatory postsynaptic potential (EPSP). Alternatively, binding of
inhibitory neurotransmitter ligands, such as GABA and glycine, produces an inhibitory
postsynaptic potential (IPSP). These ligand-gated receptors are also known as ionotropic or fast
receptors.
G-protein linked receptors are indirectly linked to ion channels, via a second messenger system
involving G-proteins and adenylate cyclase. These receptors are neither precisely excitatory nor
inhibitory and modulate the actions of the classic excitatory and inhibitory neurotransmitters
such as glutamate and glycine. These receptors tend to have an inhibitory effect if they are linked
to the Gi protein in the cell membrane, and a more excitatory effect if linked to the Gs protein.
G-protein linked receptors are known as metabotropic or slow receptors and examples include
GABA-B, glutamate, dopamine (D1 and D2), 5-HT1A, 5-HT1B, 5-HT1D, 5-HT2A,
5-HT2C receptors.
Serotoning receptors
Type
Distribution
Postulated Roles
5-HT1 Brain, instetinal nerves
Neuronal inhibition, behavioural
effects, cerebral vasoconstriction
5-HT2 Brain, heart, lungs, smooth
muscle control, GI system,
blood vessels, platelets
Neuronal excitation,
vasoconstriction, behavioural
effects, depression, anxiety
5-HT3 Limbic system, ANS
Nausea, anxiety
5-HT4 CNS, smooth muscle
Neuronal excitation, GI
5-HT5, Brain
6, 7
Not known
Noradrenaline receptors
Type
Distribution
Postulated Roles
Alpha1 Brain, heart, smooth
muscle
Vasoconstriction, smooth muscle control
Alpha2 Brain, pancreas, smooth
muscle
Vasoconstriction, presynaptic effect in
GI (relaxant)
Beta1
Heart, brain
Heart rate (increase)
Beta2
Lungs, brain, skeletal
muscle
Bronchial relaxation, vasodilatation
Beta3
Postsynaptic effector cells Stimulation of effector cells
Dopamine receptors
Type
Distribution
Postulated Roles
D1, 5like
Brain, smooth muscle
Stimulatory, role in
schizophrenia?
D2, 3, 4- Brain, cardiovascular system,
like
presynaptic nerve terminals
Inhibitory, role in
schizphrenia?
Acetylcholine receptors
Type Distribution
Postulated Roles
M1
Nerves
CNS excitation, gastric acid
secretion
M2
Heart, nerves, smooth muscle
Cardiac inhibition, neural
inhibition
M3
Glands, smooth muscle,
endothelium
Smooth, muscle contraction,
vasodilation
M4
?CNS?
Not known
M5
?CNS?
Not known
NM
Skeletal muscles neuromuscular
junction
Neuromuscular transmission
NN
Postganglionic cell body dendrites Ganglionic transmission
Co-transmission
Several different neurotransmitters can be released from a single nerve terminal, including
neuropeptides and small molecule neurotransmitters. As well as acting as neurotransmitters in
their own right, neuropeptides can act as co-transmitters. As
co-transmitters, they can activate specific pre- or postsynaptic receptors to alter the
responsiveness of the neuronal membrane to the action of ‘classical’ neurotransmitters, such as
noradrenaline and serotonin.
Serotonin, noradrenaline and dopamine are involved in the control of many of our mental states,
sometimes acting on their own and at other times acting together (illustrated in the diagram
below). These and other neurotransmitters are likely to play a pivotal role in the pathological
basis of mental illness and diseases of the brain. Much of the evidence for this stems from the
fact that most of the effective antidepressant drugs are thought to work by changing either
serotonin and/or noradrenaline metabolism, or receptor sensitivity to these neurotransmitters.
Understanding the numerous neurotransmitters, their receptors, locations and interactions with
one another has been central to the design of medicines for mental illness. This acquired
knowledge has led to the development of successful products for many brain disorders including
epilepsy, schizophrenia, Parkinson’s disease, depression, anxiety disorders and migraine .
Monoamine Reuptage and Breakdown
After release from the presynaptic membrane, serotonin and noradrenaline are cleared from the
synapse by the process known as reuptake. This terminates the neurotransmitter effect. In
addition, ‘used’ monoamines are broken down by enzymes such as monoamine oxidase in the
synapse.
The Following Article from:
International Health Supplement Education Foundation
Dallas, Texas
Learn How Neurotransmitters Chemically Generate . . .
Feelings of Happiness
Drive and Motivation
Ability to Focus
Emotional Stability
Mental Alertness
Good Feelings Toward Others
Calmness in the Face of Difficulty
Relieve the symptoms of neurotransmitter
insufficiency by restoring daily supplies to
maintain the brain's chemical balance.
Understanding Neurotransmitters
In your brain are ten billion neurons (brain cells). Between each and every one of
these are neurotransmitters. Chemical messengers that TRANSMIT thought
from one cell to the next, allowing brain cells to "talk to each other." What's
most fascinating is that how you experience emotion and how you feel, is dictated
by certain neurotransmitters, as illustrated in the following example.
COLORS OF YOUR MIND
A RED GLASS held in front of a flashlight will transmit light through the glass
as RED. It has no choice but to transmit as RED. A GREEN glass transmits the
light as GREEN. The colors RED and GREEN can be compared to different
emotions or feelings you feel. The glass is the transmitter, the beam of light is like
your thought. Different neurotransmitters, like different colored glasses, will
determine which emotion or feeling your thought is transmitted in. Some
transmitters transmit thought in a positive, happy or euphoric feeling; some
transmit thought in a relaxed, calm and quiet mood; some transmit thought in a
highly motivated, intense and focused "state of mind," and so on.
MOODS CHANGE . . .
The types of transmitters change regularly between cells in your brain to meet
the needs of your current circumstance. At night, to induce sleep, the brain needs
to raise its level so certain thoughts are transmitted in a calming, quieting and
relaxing way for you to sleep well. In the morning it must lower its levels of these
transmitters and raise excitatory transmitter levels. During exercise it increases
levels of euphoria inducing transmitters. During times of stress it must raise
levels of another transmitter that helps you to remain clam and in control. When
in pain, inhibitory transmitters are used by the brain to restrict the transmission
of pain. The more present the less pain you feel!
IT IS CRITICAL that all of the major neurotransmitters be present daily and in
sufficient amounts in order for the brain to be chemically balanced. When there
are insufficient amounts of one or more of these it upsets the ratio and symptoms
are experienced.
___________________________________
NEUROTRANSMITTER DEFICIENCIES
o
o
o
o
o
o
o
o
Depression
Lifelessness
Moods
Irritability
Sleeplessness
Anxiety/Panic
Brain Fog
Stress Damage
___________________________________
Depleted supplies of "feel good" transmitters means it will be impossible for you
to feel happy, upbeat, motivated or on track. You will feel just the opposite: A
decrease in energy and interest, feelings of worthlessness and a pervasive sense of
helplessness to control the course of your life.
Certain transmitters, when depleted, may cause you to be easily agitated or
angered, experience mild to severe anxiety and have sleep problems. You may
feel more psychological and physical pain. These can all be symptoms of
neurotransmitter insufficiency.
IN CHILDREN, when supplies of desirable transmitters are too low, it is a major
cause of excitable, uncontrollable behavior, and an inability to focus or pay
attention. An extremely low level of some neurotransmitters creates the potential
of violent behavior.
MAIN CAUSES
of Neurotransmitter Deficiencies
 GENETIC: A person's genetic make up is responsible for low, high or balanced
levels of transmitters from birth.
 STRESS: Stress depletes neurotransmitters! Any type of stress . . . lack of sleep,
everyday mental and emotional battles or poor health, will deplete "feel good"
transmitters. This results in a reduction of transmitters needed for sleep, as well as
pain blocking transmitters.
 DIET: The specific amino acids that our brains manufacture transmitters from are
frequently not supplied by our modern diet or in the way our brain best utilizes
them. As stress further depletes supplies it is difficult, if not impossible, for the
brain to restore necessary amounts to proper levels. More information on the
subject of diet can be found under the heading "Amino Acid Link."
Major Neurotransmitters "Feel Good"





ENDORPHINS (Opiods): Mood elevating, enhancing, euphoric. The more
present, the happier you are! Natural pain killers.
NOREPINEPHRINE: Excitatory, feel happy, alert, motivated. Anti-depressant,
appetite control, energy, sexual arousal.
DOPAMINE: Feelings of bliss and pleasure, euphoric, appetite control,
controlled motor movements, feel focused.
ACETYLCHOLINE: Alertness, memory, sexual performance, appetite control,
release of growth hormone.
PHENYLETHYLMINE (PEA): Feelings of bliss, involved in feelings of
infatuation (high levels found in chocolate).
Inhibitory


ENKEPHALINS: Restrict transmission of pain, reduce craving, reduce
depression.
GABA (Gamma Amino Butyric Acid): Found throughout central nervous
system, anti-stress, anti-anxiety, anti-panic, anti-pain; Feel calm, maintain
control, focus.
Hormonal



SEROTONIN: Promotes and improves sleep, improves self esteem, relieves
depression, diminishes craving, prevents agitated depression and worrying.
MELATONIN: "Rest and recuperation" and "anti-aging" hormone. Regulates
body clock.
OXYTOCIN: Stimulated by Dopamine. Promotes sexual arousal, feelings of
emotional attachment, desire to cuddle.
___________________________________
How Can You Restore Proper Levels of These
Neurotransmitters?
Major transmitters are manufactured inside neurons (brain cells) and then used
as needed. Neurons specifically use two key amino acids as precursors, or
building blocks, to make transmitters from. By supplying your brain with a
ready daily supply of these 2 amino acids, neurotransmitter levels are
maintained.
How Do You Feel When Transmitters Are Restored?
As levels are restored, you notice that you sleep better, think more clearly, are
slower to anger, feel more at peace and relaxed. You find you're more positive,
focused and motivated. These feelings begin to replace negative thoughts,
hopelessness and depression.
___________________________________
Amino Acid Link
How We Feed Our Brain Directly Affects
Our Production of Neurotransmitters.
"If the 'smart nutrient' intake of all Americans was optimal, the widespread use
of psychotropic drugs that are designed to treat depression, anxiety, senility and
personality disorders would greatly diminish."
--Robert Haas
renowned author on nutrition
Little Known Facts About Amino Acids, Vitamins, and Minerals
...
During the Gulf War U.S. fighter pilots were given an amino acid, vitamin, and
mineral formulation to relieve the debilitating stress of combat, enhance mental
sharpness and improve sleep between missions (documented pilot report available.)
The same amino acid, vitamin, and mineral formulation works for animals! In
large poultry farms where thousands of chickens are housed in one large area for
months, the amino acid and vitamin formulations are placed in the drinking water
of the chickens to keep them from killing each other!
___________________________________
The Two Key Amino Acids
Your Brain Uses to Make Neurotransmitters From -Phenylalanine* is an essential amino acid, meaning that if you're not getting it
from your diet then your brain isn't getting what it needs to make the transmitters
that cause you to feel happy, loving and motivated. The other amino acid,
Glutamine, is a conditionally essential amino acid. It is used to make
neurotransmitters which keep you feeling calm, focused and in control, but during
periods of stress the body cannot make its own supply of glutamine and needs an
outside source, diet or otherwise.
*The all natural FOOD supplement Phenylalanine should not be confused
with the CHEMICALLY ALTERED form of phenylalanine which is in the
artificial sweetener Aspartame.
Three Main Challenges
in Providing the Brain with a
Daily Supply of These Key Amino Acids



DIET: Overharvesting of fields resulting in nutrient depleted soils, fruits and
vegetables not allowed to fully ripen on the vine, and over-processing of
foods have all combined over the last century to rob our diets of many lifegiving nutrients. Experts in the field of brain nutrition all agree that it is
virtually impossible to get the necessary supply of the specific amino acids
from our American Diet that our brain needs to create enough of the
neurotransmitters that keep us feeling balanced and happy.
BLOOD BRAIN BARRIER (BBB): The BBB is a membrane or sack that
completely surrounds the brain and filters all of the blood as it enters the
brain. The difficulty in acquiring the high levels of the specific amino acids
the brain needs to manufacture the "feel good" transmitters exists because
other nutrients compete with them for entry through the BBB. For example,
it is difficult to impossible for the two key amino acids to pass through the
BBB when PROTEIN and OTHER AMINO ACIDS are present because they will
compete with them for entry through the BBB. Thus, the brain cannot
readily utilize these amino acids from protein sources such as meat, eggs and
dairy products. The same is true when they are combined in a formula
containing other amino acids or unassociated nutrients.
SYNERGISM: It has been discovered that in order for the brain to establish
the proper ratio of one neurotransmitter to another it uses these two key
amino acids best when formulated together with trace amounts of other
specific associated co-factor nutrients. The inter-conversion process of these
amino acids, in order to function optimally, REQUIRES these certain cofactors. When all of the necessary raw elements are present together, and in
exact formulation, a higher quality and quantity of ALL desired transmitters
can then be naturally produced. The result is that brain chemical balance is
then possible.
STRESS
The Neuro-Body Link
___________________________________
Stress Depletes Neurotransmitters
In handling daily stress the brain uses feel good transmitters called endorphins
(opiods). When large amounts are needed to handle stress, the RATIO of many
of the other transmitters, one to another, becomes upset creating a chemical
imbalance. We begin to FEEL stress more acutely -- a sense of urgency and
anxiety creates more stress. Harmful chemicals are released in our bodies that do
damage, causing more stress. We call this vicious cycle the "stress cycle."
Emotional fatigue can result, and be experienced and felt as depression.
The body responds to EMOTIONAL STRESS exactly as it responds to
PHYSICAL DANGER. Without our being aware of it, usually not feeling it at all,
our bodies are continuously reacting to emotions such as frustration, irritation,
resentment, hurt, grief and anxiety -- responding to these MENTAL and
EMOTIONAL STRUGGLES with a primitive physiological "fight or flight"
response designed to prepare our bodies to face immediate danger. In modern
day life we don't fight, we don't flee. Instead, the high-energy chemicals
produced in many everyday situations boil inside of us, potentially taking years
off our lives.
Almost all the body functions and organs react to stress.
Your body responds to stress with a series of physiological changes that include
increased secretion of adrenaline, elevation of blood pressure, acceleration of the
heartbeat, and greater tension in the muscles. Digestion slows or stops. Within 24
to 48 hours after a stress-anxiety-anger reaction, major physical symptoms can
and do occur.
Stress creates an excellent breeding ground for illness.
Increased adrenaline production causes the body to step up its metabolism of
proteins, fats and carbohydrates to quickly produce energy for the body to use.
The pituitary gland increases its production of andrenocorticotropic hormone
(ACTH), which in turn stimulates the release of the hormones cortisone and
cortisol. These have the effect of inhibiting the functioning of disease fighting
white blood cells and suppressing the immune system response. This complex of
physical changes known as the "fight or flight" response is also the reason that
stress can lead to nutritional deficiencies.
Long-Term Stress is Particularly Dangerous.
Continual stress eventually wears out the body. Consider the fact that only a few
of the veterans, Russian or German, who fought during the siege of Stalingrad
lived to age 50. Few lived to 45, and most died soon after their 40th birthdays. All
of these individuals suffered extreme stress 24 hours a day for more than six
months.
With Amino Acids, Vitamins, and Minerals, Opiods
(Endorphin) Levels Are Maintained.
High-energy chemicals are not pumped into your body to do damage. You
remain relaxed, at peace, and maintain a sense of well-being.
___________________________________
Researchers estimate that stress contributes to as many as 80% of all major
illnesses that include cardiovascular disease, cancer, endocrine and
metabolic disease, skin disorders and infectious ailments of all kinds.
Studies by the American Medical Association have shown stress to be a
factor in over 75% of all illnesses today.
Research linking stress to a variety of diseases and illnesses has been the
subject of more than 20,000 scientific studies.
___________________________________
PMS (Premenstrual Syndrome): Dr. James Chuong, director of
Baylor University Medical School's PMS Program, has found LOW
LEVELS of endorphins ("feel good" neurotransmitters) in women
suffering from PMS!
Afternoon Delight
The afternoon hunger that leads us to the cookie jar, soda pop or chocolate bar
may have more to do with a brain chemical imbalance than actual hunger. When
the stress of the day accumulates and too many of our own natural "feel good"
transmitters become depleted we reach for something to make us feel better.
Consider the fact that chocolate contains high amounts of phenylethylamine, a
neurotransmitter that causes feelings of bliss and is involved in feelings of
infatuation. Hence, the love affair many "chocoholics" have with chocolate! Four
decades of research strongly suggests that when the brain has adequate supplies
of the specific amino acids that it uses to make the transmitters that help us to
think clearly, pay attention and sleep well, behavior tends to be normal. Did you
ever notice that when you are feeling good you are less hungry?
Amino Acids, Vitamins, and Minerals Therapy
Neurotransmitter deficiencies can be expressed as both
psychological (behavioral pattern) and physiological (physical
craving) problems. Amino acid therapy provides the nutrition
needed to overcome the physiological problems so that 12-step
recovery programs, counseling and diets can work.
Neurotransmitter Function
Drugs that Affect
Neurotransmitters
Neurotransmitter
Deficiencies Result In
Amino Acid
Supplement
Lack of drive,
depression, lack of
energy
L-phenylalanine
Norepinephrine
Arousal, energy,
drive
Cocaine, speed,
caffeine, tobacco
GABA
Staying calm,
relaxation, focus
Valium, alcohol,
Free-floating anxiety,
marijuana, tobacco fearfulness, insecurity,
can't relax or sleep,
unexplained panic
Endorphins
Psychological /
physical pain
relief, pleasure,
reward, good /
loving feelings
toward others
Heroin, marijuana,
alcohol, sugar,
tobacco
Overly sensitive, feelings dLof incompleteness,
phenylalanine
anhedonia (inability to
experience pleasure
normally), world lacks
color, inability to love
Serotonin
Emotional
stability, pain
tolerance, selfconfidence
Sugar, marijuana,
ecstasy, tobacco
Depression, obsession,
worry, low self-esteem,
sleep problems, hunger,
irritability
L-glutamine
Chromium
Picolinate
Increases LTryptophan
availability
ADD / ADHD
Attention Deficit (Hyperactivity) Disorder
ADD has nothing to do with intelligence. Many people with ADD are highly
intelligent. According to experts in the field of ADD/ADHD, the disorder is the
result of a neurotransmitter imbalance.
Recognizing ADD
Not all children who are naturally rambunctious or extraordinarily curious have
ADHD. Nor do all disorganized adults who have many things going on at one
time have ADD. A professional diagnosis is the best way to determine ADD /
ADHD in any individual. However, the following description, as given by experts
in the field of ADD / ADHD, serves as a guide.
A high level of frustration causes ADD people to be
ADD / ADHD, like
impatient. Whatever is going on -- they want it to go
depression, occurs in
quickly and be finished. People with ADD suffer from
varying degrees of
"overload"; they have a heightened awareness of
intensity. Not all
incoming environmental stimuli. Their world tends to
be too bright, too loud, too abrasive and too rapidly
symptoms are present.
changing for comfort. Unable to filter out normal
There may be just one or a
background "noise" they find it difficult to
combination of them.
concentrate on a task before them. Disorientation to
time and space is often a problem. For instance they
may have to stop and think which hand is their right or left. They may have
difficulty following a set of instructions or reading a map. ADD people tend to be
disorganized. They have trouble making and carrying out plans. Many ADD
people are hyperactive. As youngsters they're constantly moving, squirming,
twisting and getting into everything. As adults they're restless and easily
distracted. They often tend to forget appointments, to pay bills and complete
tasks. Because they're always in a hurry, delays of any kind make them frantic.
ADD people live under such stress, frustration is difficult to tolerate, and when
they're frustrated they're likely to become angry.
Hormones
The Amino Acid Link
The Hypothalamus
A little place IN YOUR BRAIN called the Hypothalamus, a gland about the size
of the tip of your thumb, is often referred to as the "master controller" as it
regulates your entire hormonal (endocrine) system, orchestrating what all the
other glands of the endocrine system do. In addition to this aspect of metabolism
the hypothalamus also regulates body temperature and the hunger response.
More blood gushes through the hypothalamus than any part of the brain.
The ENDOCRINE
SYSTEM'S glands (a gland
is an organ or tissue that
secretes HORMONES,
tell your bones how much calcium to store or substances for use
release, influencing how strong your bones are elsewhere in the body, into
the bloodstream) include
determine height, bone and muscle growth
the pituitary, thyroid,
directly affect your mood
thymus and adrenal glands,
tell your brain when you will sleep and for how
as well as the pancreas,
long
ovaries and testes.
Hormones




Hormones determine







at what rate to metabolize
when and where to store fat
levels of estrogen, progesterone and
testosterone
sex drive
blood pressure
blood sugar levels
numerous other functions
HORMONES float through
your blood, messengers
telling various cells that
they come in contact with
what to do. They are
essential to life as they
regulate and determine
how well your body
performs many of its
functions. Hormones affect
your overall health and
well-being, and determine
how youthful you remain
throughout life.
Keeping the Master Controller in Good Health
The various glands of the endocrine system require different
amino acids and nutrients to function optimally. However, the
hypothalamus, this master controller that orchestrates and
regulates your entire endocrine system, in order to function
properly, MUST HAVE the essential amino acid phenylalanine.
Essential meaning that the body cannot convert it from other
nutrients and so it is dependent on an outside source to acquire
sufficient amounts of this amino acid. If the diet is not providing
adequate amounts of phenylalanine, then recommended
therapeutic dosage is 500 to 2000 milligrams per day.
Symptoms of ADD / ADHD
Adults
Children
 A sense of under achievement (cannot get
life together)
 Head-knocking
 Difficulty getting organized
 Lack of concentration
 Chronic procrastinating
 Tendency to disturb others
 Starting new tasks and projects without
completion
 Self-destructive behavior
 Impulsive speaking
 Frequent mood changes
 Being bored easily (unable to sustain
attention over prolonged period)
 Speech and hearing disorders
 Easy distractibility (a tendency to drift away
in a conversation or thought)
 Temper tantrums
 Creative, intuitive and highly intelligent
(flashes of brilliance in the midst of
disorganization)
 Impatience
 Needless worrying or a sense of impending
doom
 Extreme distractibility
 Difficulty solving problems or managing time  Forgetfulness
 Low tolerance for stress and otherwise
ordinary problems
 Inability to finish tasks
 Mood swings or depression
 Learning disabilities
 Tendencies toward addictive behavior
 A tendency to become
frustrated quickly
 Family history of ADD
 Inability to sit still for any length
of time
.
 Clumsiness
.
 Sleep disturbances
.
 Failure in school despite
average or above average
intelligence
Amino Acids are the Building Blocks of All Life!
In order to function properly, the body MUST HAVE the essential amino acid
phenylalanine. Essential meaning that the body cannot convert it from other
nutrients and so it is dependent on an outside source to acquire sufficient
amounts of this amino acid. If the diet is not providing adequate amounts of
phenylalanine then recommended therapeutic dosage is 500 to 2000 milligrams
per day.
Menopause
Just before menopause many women experience anxiety. The body ceasing to
ovulate brings on a major transition largely due to the reduction of the hormones
estrogen and progesterone.
Many different organs and systems of the body are affected by this change as
many will take over from the ovaries to produce some estrogen and other
hormones. The brain and body has to adjust to all of the changes. The transition
usually lasts up to five years.
Premenstrual Syndrome (PMS)
According to the National Women's Health Resource Center, as many as 95% of
women have some premenstrual discomfort; for 30% to 35% of them it's severe.
Besides hormonal imbalance being a cause, it has also been discovered that
women suffering with PMS have LOW ENDORPHIN LEVELS, the brain's
natural "feel good" chemicals. This might explain why PMS has also been linked
to clinical depression!
In both instances of menopause and PMS, emotional stress
exaggerates the symptoms experienced. Relieving stress and
anxiety through proper brain nutrition will help to lessen the
associated difficulties of both experiences, making the transition
periods smoother. In addition, by supplying the hypothalamus
with sufficient amounts of the essential amino acid,
phenylalanine, for proper regulation of the hormonal system,
symptoms may also be improved