Function of Neurotransmitters

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Important Neurotransmitters & Their Functions

As mentioned already, about 50 neurotransmitters have been discovered so far. Out of these, a few ofthe most important neurotransmitters and their functions are discussed below.

Acetylcholine

This neurotransmitter was discovered in the year 1921, by Otto Loewi. It is mainly responsible forstimulating muscles. It activates the motor neurons that control the skeletal muscles. It is alsoconcerned with regulating the activities in certain areas of the brain, which are associated withattention, arousal, learning, and memory. People with Alzheimer's disease are usually found to have asubstantially low level of acetylcholine.

Dopamine

Dopamine is the neurotransmitter that controls voluntary movements of the body, and is associatedwith the reward mechanism of the brain. In other words, dopamine regulates the pleasurableemotions.

Drugs like cocaine, heroin, nicotine, opium, and even alcohol increase the level of this

neurotransmitter. A significantly low level of dopamine is associated with Parkinson'sdisease, while the patients of schizophrenia are usually found to have excess dopamine inthe frontal lobes of their brain.

Serotonin

Serotonin is an important inhibitory neurotransmitter, which can have a profound effect on emotion,mood, and anxiety. It is involved in regulating sleep, wakefulness, and eating. It plays a role inperception as well. The hallucinogenic drugs like LSD actually bind to the serotonin receptor sites, andthereby block the transmission of nerve impulses, in order to alter sensory experiences.

A significantly low level of serotonin is believed to be associated with conditions like depression,suicidal thoughts, and obsessive compulsive disorder. Many antidepressants work by affecting thelevel of this neurotransmitter.

Gamma-aminobutyric Acid (GABA)

GABA is an inhibitory neurotransmitter that slows down the activities of the neurons, in order toprevent them from getting over excited. When neurons get over excited, it can lead to anxiety. GABAcan thus help prevent anxiety.

GABA is a non-essential amino acid, that is produced by the body from glutamate. A low level ofGABA can have an association with anxiety disorders.Drugs like Valium work by increasing thelevel of this neurotransmitter. Alcohol and barbiturates can also influence GABA receptors.

Glutamate

Glutamate is an excitatory neurotransmitter that was discovered in 1907 by Kikunae Ikeda of TokayImperial University. It is the most commonly found neurotransmitter in the central nervous system.Glutamate is mainly associated with functions like learning and memory. An excess of glutamate ishowever, toxic for the neurons. An excessive production of glutamate may be related to thedisease, known as amyotrophic lateral sclerosis (ALS) or Lou Gehrig's disease.

Epinephrine and Norepinephrine

Epinephrine (also known as adrenaline) is an excitatory neurotransmitter, that controls attention,arousal, cognition, and mental focus. Norepinephrine is also an excitatory neurotransmitter, and it


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regulates mood and physical and mental arousal. An increased secretion of norepinephrineraises the heart rate and blood pressure.

Endorphins

Endorphins are the neurotransmitters that resemble opioid compounds, like opium, morphine, andheroin in structure. The effects of endorphins on the body are also quite similar to the effects

produced by the opioid compounds. In fact, the name 'endorphin' is actually the short form for'endogenous morphine'.

Like opioids, endorphins can reduce pain, stress, and promote calmness and serenity. The opioiddrugs produce similar effects by attaching themselves to the endorphin receptor sites. Endorphinsenable some animals to hibernate by slowing down their rate of metabolism, respiration, and heartrate.

Melatonin

It is the hormone produced by the pineal gland that also acts as a neurotransmitter. It basicallycontrols the sleep-wake cycle. It is also associated with controlling mood and sexual behavior. Theproduction of melatonin is dependent on light. Light to the retina inhibits the production of melatonin,while darkness has a stimulating effect on its production.

Nitric Oxide

It is a gas that acts both as a hormone and neurotransmitter, depending on the specific requirement.

It can cause the blood vessels to dilate, besides preventing the formation of clots. This in turn, can

promote the circulation of blood. Nitric oxide can increase the level of oxygen in the body, and

improve memory, learning, alertness, and concentration. It is also responsible for causing the smooth

gastrointestinal muscles to relax.

To sum up, neurotransmitters are chemicals that allow the nerves to communicate with each other,

and thus, regulate the various functions of the body. A substantially high or low level of thesechemicals can alter the functions of the entire nervous system.

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Dopamine

Pleasure, Love, and Integration of Thoughts and Feelings

Phenylalanineandtyrosineare precursors to the bodys three fight or flightneurotransmitters, dopamine, epinephrine (adrenaline) and norepinephrine.Phenylalanineconverts to>Tyrosineconverts to>DOPAconverts to>Dopamine

Dopamine is widespread in the brain as well as the rest of the nervous system. This

neurotransmitter plays a critical role in the control of movement. It has a stimulating effect on the
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heart, the circulation, the rate of metabolism, and is able to mobilize many of the bodys energy

reserves. It helps to modulate brain activity, control coordination and movement, and regulate the

flow of information to different areas of the brain. Dopamine is believed to release chemicals that

allow us to feel pleasure (e.g., endorphins). A massive disturbance of dopamine regulation in the

brain can result in a person no longer being able to respond emotionally or express his or her

feelings in an appropriate way (e.g., schizophrenia).

The main precursor for this neurotransmitter is the nonessential amino acid tyrosine. While tyrosine

is contained in many foods, it is classified as a nonessential amino acids because ordinarily our

bodies can create it. Still, deficiencies in the production of tyrosine can occur, and increased dietary

supplementation may be necessary. Folic acid, niacin, iron, and B6are necessary cofactors.

Optimal quantities of Dopamine result in:

Feelings of pleasure Feelings of attachment/love

Sense of Altruism Integration of thoughts and feelings

Dopamine Deficiencies result in:

Anhedonia Lack of ability to feel love, sense attachment to another Lack of remorse about actions Distractibility

Supplements required:

L-Phenylalanine Vitamin B6

Useful sources of building blocks for dopamine:

Apples Beets Blue-green algae Celery Chicken Cucumber Fish Green leafy vegetables Honey Cheese Sweet peppers Tofu


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Watermelon

Norepinephrine

Energy, Stimulation, Fight or Flight

Phenylalanineand tyrosineare precursors to norepinephrine and epinephrine.Phenylalanineconverts to>Tyrosineconverts to>DOPAconverts to>Dopamine

converts to>Norepinephrineconverts to>Epinephrine

Norepinephrine, also known as noradrenaline, is a neurotransmitter found in the sympathetic

nervous system. The sympathetic nervous system stimulates the heart, blood vessels, sweat glands,

the large internal organs, and the adrenal medulla in the brain. Like dopamine, norepinephrine has a

stimulating effect, fosters alertness, and plays an important regulatory role in long-term memory

and learning. It also protects endorphins from being broken down prematurely. Optimal levels of this

transmitter can stimulate a sense of wellbeing or even create a euphoric effect in stressful

situations. Yet excess norepinephrine can fuel the physiological expressions of fear and anxiety, as

may be the case for people who suffer from anxiety disorders.

The amino acid tyrosine, found in high concentrations in cheese, is converted by specific reactions

into at least two neurotransmitters norepinephrine and dopamine. Norepinephrine is produced

from dopamine, with the help of the amino acids phenylalanine, lysine, and methionine. Vitamins C

and B6, magnesium, and manganese are important cofactors.

Norepinepherine Functions in:

Arousal, energy, drive Stimulation Fight or Flight

Norepinepherine Deficiencies result in:

Lack of energy Lack of motivation First state called depression

Supplement required for norepinephrine:

1-phenylalanine Vitamin B6

Useful sources of building blocks for norepinephrine:


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Almonds Apples Avocado Bananas Beef liver or kidney Blue-green algae Cheese Fish Most green vegetables Lean meat Nuts Grains Pineapple Poultry Tofu

Serotonin

Emotional Stability, Calm, Sleep, Appetite Control

5-HTP (5-hydroxytryptophan)is a precursor to serotonin. And serotonin can furtherconvert to melatonin.5-HTPconverts to>Serotoninconverts to>Melatonin

Serotoninaffects numerous bodily systems. There are 17 known types of serotonin receptors, with

the largest quantity of serotonin being produced in the intestines. Serotonin acts in a variety of waysand is involved in about one quarter of all the bodys biological processes. Serotonin stimulates

release of a hormone, melatonin within the pineal gland, which regulates the body clock and sleep.

It has also been shown to play a role in the onset of migraine headaches by causing blood vessels to

constrict, affects blood clotting, heartbeat, and mood (it can reduce depression). Alterations of

serotonin activity is a common effect of psychedelic drugs, (e.g., LSD is structurally similar to

serotonin).

Serotonin is synthesized directly from the essential amino acid tryptophan, which must come from

the diet, with the assistance of Vitamin B6and carbohydrates. Yet the amount of tryptophan that

gets into the brain depends on the relative amounts of other amino acids in your blood. Because

amino acids are the building blocks of protein, one might think that eating a high-protein mealwould be a good way to get more tryptophan into the brain. But because protein foods typically

contain much smaller amounts of tryptophan than other amino acids, this is not the best strategy. In

contrast, a high-carbohydrate meal changes the odds in favor of tryptophan by increasing insulin,

which pulls competing amino acids out of our blood and into our cells. Even though the actual

amount of tryptophan in the blood hasnt changed, more passes into the brain. This helps to explain

why people often feel comforted after eating carbohydrate-rich foods (e.g., cake) and depressed
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people tend to binge on more carbohydrates.

Serotonin Functions in:

Emotional stability Reduces aggression Sensory input Sleep cycle Appetite control

Serotonin Deficiencies result in:

Irritability Irrational emotions Sudden unexplained tears Sleep disturbances

Supplement required for serotonin:

5HTP or l-tryptophan from food Calcium, and Magnesium

Useful sources of building blocks for serotonin:

Bananas Beets Blue-green algae Brown rice Cheese Fennel Figs Fish Ham Legumes Milk Nuts Pasta Pineapple Potatoes Radishes Spinach Tomatoes Turkey Whole grains


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GABA (Gamma-Amino Butyric Acid)

Tension and Stress Control

Glutamineis a precursor to GABA(Gamma-Amino Butyric Acid).Glutamineconverts to>GABA

When brain experiences an abundance of nervous tension and stress, it can be caused by a surplus

of norepinephrine or epinephrine (adrenaline). To neutralize this extra adrenaline, the brain

produces neurotransmitters, one of which is GABA, that have inhibitory effects upon the nervous

system.

The following diagrams explain how the brain uses GABA to calm excessive nervous tension and

stress. The diagrams will also show the effect barbiturates, benzodiazepines and alcohol can have

on the same brain cells.

Please Note:The two inner rings are receptors for other neurotransmitters that have not yet been

scientifically identified. But scientists have discovered that the two inner rings are sensitive to

external source substances or chemicals, such as benzodiazepines, barbiturates and alcohol.These

external substances attach to the GABA receptor site like neurotransmitters, and can have an effect

on the brain similarly to their respective neurotransmittesrs. However, when an external source

substance is used to take the place of a natural internal substance for an extended period of time,

the body begins to reduce production of those natural chemicals. This can create a deficieny in

these naturally occuring chemicals.

L-Glutamine is an amino acid that in a precursor to GABA. Using a nutritional supplement that

contains L-Glutamine along with a balanced diet can support the natural replenishment of GABA, aswell as other neurotransmitters.

Diagram One: The GABA Receptor Complex
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Think of the GABA receptor complex as a round object, like a donut, consisting of three rings, and a

center.

Center Opening: Chloride ChannelChloride neutralizes norepinephrine, thereby calming stress and nervousness. If

any two of the rings fill with their respective chemicals, they will cause the donutto tighten, widening the chloride channel to allow more chloride into the brain toneutralize the adrenaline.

Outer Ring: GABA Sensitive RingAs the brain produces GABA, the molecules attach to the GABA Ring

Second Neurotransmitter Ring: Also sensitive to benzodiazepinesOther neurotransmitters and benzodiazepine molecules attach to the middle ring,which can also assist in opening the chloride channel.

Third Neurotransmitter Ring: Also sensitive to barbiturates and alcoholOther neurotransmitters, barbiturate and alcohol molecules attach to the innerring, which can also assist in opening the chloride channel.

GABA

The Chloride Channel

Diagram Two: GABA and The Chloride Channel

As the GABA Sensitive Ring and either the Second or Third Neurotransmitter rings begin to fill with

their respective molecules, they tighten the whole GABA complex, thereby widening the chloride

channel to allow more chloride to enter. Since chloride neutralizes norepinephrine, this process cancalm excessive nervousness, tension, and stress.

Since the Second and Third Neurotransmitter Rings are sensitive to external source substances such

as benzodiazepines, barbiturates and alcohol, these external substances can cause the Chloride

Channel to open, thereby assisting in the neutralizing of additional adrenaline.

However, prolonged use of any external substances that cause the GABA complex to widen without

the natural production of GABA, can eventually send the message to the brain that GABA is no

longer needed. The brain doesnt produce neurotransmitters to store, rather it produces them for

immediate use. Therefore, if the brain continues to receive the message that GABA is not needed to

widen the chloride channel, the brain may finally slow down the GABA production, thereby creatinga deficiency.

It takes at least two of the rings filling with molecules to tighten the whole complex. The amino acid

L-Glutamine is a precursor to GABA. Therefore, an amino acid supplement containing L-

Glutamine can nutritionally support the natural production of GABA.


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GABA Receptors

Diagram Three: Benzodiazepines and Barbiturates

If the second and third ring are filled with an abundance of external source substances such as

benzodiazepines, barbiturates and alcohol, a dangerous thing can happen. The Chloride Channel can

be opened wide enough to allow enough chloride to enter to substantially neutralize the

norepinephrine in the brain.

Since norepinephrine is a necessary transmitter that the brain uses to control the vital organs, which

are involuntary muscles, there must be norepinephrine available for the brain to keep these muscles

operating. Without any norepinephrine at all, the heart, lungs, and other vital organs can stop

working.


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Function of Neurotransmitters