What is serotonin? What is its function?

Serotonin is a chemical produced by the human body, which functions as a neurotransmitter. It is considered by some researchers as the chemical responsible for maintaining balance our mood, so a deficit of serotonin lead to depression.

The origin of the word serotonin comes from its discovery in 1948 when Maurice M. Rapport's first isolated initially as a type of serum affecting vascular tone. ¹

Find in this article as essential information on everything related to serotonin.

General information on serotonin

Find here some general information about serotonin. More details and additional information in the body of this article.

• Serotonin is a chemical produced by the human body that functions as a neurotransmitter.
• It is commonly regarded as the chemical responsible for maintaining balance our mood.
• Serotonin is produced through a biochemical conversion.
• Serotonin in the brain and intestines. Most of the body's serotonin (80-90%) can be found in the gastrointestinal tract.
• Used serotonin within the brain stems within this.
• It is considered that serotonin can affect mood, social behavior, appetite and digestion, sleep, memory, and desire and sexual performance of a person.
• There is a close relationship between depression and serotonin. However scientists are still not sure whether decreased levels of serotonin contribute to depression, or conversely, depression causes decrease in serotonin levels.
• Selective reuptake inhibitors (SSRIs) can affect serotonin levels in the body.
• If excessive serotonin in the body amounts accumulate, serotonergic / serotonin syndrome may occur.
• Other ways to increase serotonin levels in the body include the induction of moods, exposed to light, exercise and diet.

What is serotonin?

Serotonin occurs through a biochemical conversion process combining tryptophan, a component of proteins, tryptophan hydroxylase, a chemical reactor. Together form the 5-hydroxytryptamine (5 - HT), also known as serotonin.²

Serotonin is most commonly known as a neurotransmitter, although some believe that this chemical is a hormone.

Whence comes serotonin?

Serotonin in the brain and intestines. Most of the body's serotonin (80-90%) can be found in the gastrointestinal (GI).Can also be found in the blood platelets and the central nervous system (CNS). ^2.3

Because serotonin can be found widely throughout the body, it is considered that this chemical influences a variety of physical and psychological functions.

As serotonin can not cross the blood-brain barrier, it is essential that the brain produces its own dose within it.

What is the function of serotonin?

As a neurotransmitter, serotonin transmits signals between nerve cells (neurons) regulating their intensity.

Serotonin is a neurotransmitter that regulates the signal between neurons.

Is widely considered that serotonin plays a key role in the central nervous system (CNS) as well as the general functioning of the body, particularly in the gastrointestinal (GI) tract.

Different studies have found links between serotonin and bone metabolism, production of breast milk, liver regeneration and cell division.

As a neurotransmitter, serotonin directly and indirectly influences in most brain cells. It is considered that serotonin may affect:

• Mood and social behavior
• Appetite and digestion
• The dream
• Memory
• Sexual desire and performance.

Links between serotonin and depression

It is not known exactly what causes depression. It is thought likely an imbalance of neurotransmitters or hormones in the body that lead to this condition.

Serotonin levels are strongly associated with depression.

There is a close relationship between depression and serotonin. However scientists are still not sure whether decreased levels of serotonin contribute to depression, or conversely, depression causes decrease in serotonin levels.

Although measurable levels of serotonin in the blood stream through an examination of serum serotonin level, is currently not possible to measure the levels of serotonin in the brain. 

Researchers still do not know if the levels of serotonin in the bloodstream reflect the levels of serotonin in the brain.

It is considered that medications such as selective reuptake inhibitors (SSRIs) can affect serotonin levels in the body, working as antidepressants and helping to relieve the symptoms of depression. Although no one knows precisely how they work.

However, a recent study may provide evidence contrary to these theories so widespread. Mice led scientists to make serotonin capacity through several behavioral tests. The mice did not show any signs of depression, which clearly suggests that factors other than serotonin are involved in the onset of depression. ¹²

SSRI's and serotonin

SSRIs are approved by the Food and Drug Administration (FDA - for its acronym in English) for the treatment of depression and are the most commonly prescribed antidepressants. The best known SSRIs include citalopram, fluoxetine, paroxetine and sertraline.

Generally, once a neurotransmitter has conveyed its neural impulse that is reabsorbed. SSRIs inhibit the reuptake of serotonin which increase serotonin levels in the body. It is considered that changing these levels of serotonin in the body to stimulate brain cells to send and receive messages, thus improving the overall mood of a person.

Recreational drugs such as MDMA and cocaine also inhibit serotonin reuptake in order to maximize their impact.

Excessive levels of serotonin may occur when consumed while two different types of drugs that affect serotonin levels in the body, for example antidepressants and migraine medicine.

SSRIs can sometimes cause side effects. They all have different chemical compositions, and their effects may vary depending on the individual. These are some of the side effects that may occur:

• Agitation
• Diarrhea
• Dizziness
• Sleepiness
• Dry mouth
• Headaches
• Insomnia
• Nausea or vomiting
• Decreased libido
• Weight gain or loss.

What is serotonin syndrome?

Serotonin syndrome is a consequence of excessive stimulation of the central nervous system and peripheral serotonin receptors. It may appear as a result of taking certain medications, illegal drugs, or dietary supplements and usually occurs when two drugs that affect serotonin levels are consumed simultaneously, eg antidepressants with migraine medicine.

Carcinoid tumors can cause excessive levels of serotonin. These cancers are commonly found in the gastrointestinal (GI). These tumors produce excess serotonin to be released. Most carcinoid tumors have no symptoms, so their detection usually occurs only when tests or procedures related to other conditions are performed.

Serotonin syndrome leads to excessive nerve activity. Signs and symptoms of this include the following:

• Agitation
• Confusion
• Increased heart rate and blood pressure
• Pupil dilation
• Diarrhea
• Headaches
• Chills
• Perspiration
• Loss of muscle coordination
• Muscle stiffness.

In more severe cases of serotonin syndrome can be life threatening. This could even lead to high fever, irregular heartbeat, seizures and unconsciousness.

Treatment

Serotonin syndrome can not be diagnosed by a single test, as it shares similar symptoms with other conditions, so the doctor will try to first rule out these other conditions before diagnosing serotonin syndrome. ^5.10

Being diagnosed, treatment will focus on trying to restore normal levels of serotonin. If symptoms are mild, stop taking the medication that caused the problem could be enough to cause discomfort disappear after a few days.

The most extreme cases of serotonin syndrome may require hospitalization. Depending on the degree of symptoms, various medications can be administered in order to relax or paralyze muscles, controlling heart rate and blood pressure, and in some cases blocking the production of serotonin.

Oxygen can also be supplied through intravenous therapy to maintain normal levels of this in the bloodstream, and also for fever and dehydration.

Natural ways to increase serotonin levels

A part of SSRIs and illegal drugs, it is considered that there are other ways to increase serotonin levels in the body. ¹¹

Legumes such as peas contain large amounts of tryptophan, the main component of serotonin.

• Induction of moods: changes in thinking, either through psychotherapy or inductance can increase serotonin levels, since the interaction between the synthesis of serotonin and mood is a two-way relationship
• Luz: which is also used as part of treatment for seasonal affective disorder; some studies suggest that also could be used to treat depression
• Exercise: Exercise has an antidepressant effect, and some research has suggested it may help increase brain serotonin function
• Diet: Foods rich in tryptophan could be linked to the improvement of mood, cognition and possibly increase our serotonin levels.

All these areas require deeper study and research, since current knowledge still speculative. 

Although there is much information regarding related to serotonin is unknown. The difficulties on the study of brain function suggest that will be a while before they can acquire full knowledge on this subject.

References:

1.        New York Times news article , Accessed 17 July 2014.
2.        WebMD Serotonin: 9 Questions and Answers , Accessed 17 July 2014.
3.        About.com Psychology What is serotonin? , Accessed 17 July 2014.
4.        Mayo Clinic Selective serotonin reuptake inhibitors (SSRIs) , Accessed 17 July 2014.
5.        Recognition and treatment of serotonin syndrome, Dr. C. Frank, Canadian Family Physician , published July               2008, Accessed 17 July 2014 article .
6.        WebMD What is serotonin syndrome? , Accessed 17 July 2014.
7.        Mayo Clinic Serotonin syndrome: Definition , Accessed 17 July 2014.
8.        WebMD Carcinoid syndrome , Accessed 17 July 2014.
9.        Mayo Clinic Serotonin syndrome: Symptoms , Accessed 17 July 2014.
10.     Mayo Clinic Serotonin syndrome: Treatment and drugs , Accessed 17 July 2014.
11.     How to Increase serotonin in the human brain without drugs, Dr. S. Young, Journal of Psychiatry and                            Neuroscience , published November 2007, Accessed 17 July 2014 article .
12.     American Chemical Society news release , Accessed 1 September 2014.