The serotonin , still called 5-hydroxy-tryptamine ( 5-HT ), is a Molécule resulting from the Tryptophane, an Amino-acid . It was initially identified as being the factor released by the blood Plaquettes involving a contraction of the blood-vessels, but it is also one of the principal neuromodulateurs of the central Nervous system.

Synthesis

Serotonin is manufactured starting from the Tryptophane, an Amino-acid which is brought to the brain by blood circulation inter alia. Certain neurons of the core of raphé, located within the cerebral trunk, transform tryptophan into 5-hydroxytryptophane (5-HTP) thanks to an enzyme, the Tryptophane hydroxylase. The 5-hydroxytryptophane is then converted into serotonin by another enzyme, the L-amino acid décarboxylase (AADC).

Mode of action

The Neuron S of the dorsal Raphé are connected to the majority of the areas of the central Nervous system (Cerveau, cerebral trunk, Spinal-cord). Serotonin is released in Synapse S and binds to receiving S located on the membrane of the post-synaptic element. Via their Axon S, the neurons of the core of raphé release serotonin on other neurons of the central nervous system, and while binding to specific receivers, modulate their electric properties.

Serotonin acts while binding to specific receivers located in the membrane of the cell S targets. The fifteen types of receivers of serotonin are divided into seven different groups (noted 5-HT1 with 5-HT7). Except for the receivers 5-HT3 which are ionotrope S, the receivers with serotonin are of type métabotrope (i.e. they act on Protéines G).

• the 5-HT2A, abundant in the brain, is suspecté to play a part in the anxiety caused by the Choix cornélien S of the daily life.

Physiological roles of serotonin

One finds serotonin in the Cerveau, where she plays the part of Neurotransmetteur or neurotransmitter, and in the digestive Système. It is implied in the regulation of functions such as the Thermorégulation, the food behaviors and sexual, the cycle Veille - Sommeil, the Douleur, the Anxiété or the Engine control. More recently, of the researchers of CNRS discovered that the serotonin of the mother played a big role in the development of the embryo. In the same way, according to a recent study, a serotonin imbalance would explain 50% of the cases of Sudden death of the infant. The activity of the neurons of raphé is related to the cycle day before-sleep. During the sleep, the neurons of raphé are quiet and thus do not release serotonin. When the subject is waked up, the neurons of raphé produce potential of action with very regular intervals. The frequency of the nerve impulses is correlated with the motor activity, which suggests that the quantity of serotonin released in the central nervous system is increased with the motor activity.

As serotonin plays a big role in the changes of emotional state, it is thought that certain molecules similar to serotonin can modify these emotional states. inhibiting selective of recaptures serotonin (substances which blocks recaptures it serotonin, for example the Fluoxétine) reduce the symptoms related on the depression or the obsessional turbid compulsifs.

A serotonin excess at the cerebral, consecutive level with the catch of these antidepressant drugs, can involve a Syndrome serotoninergic.

The regular practice of a sport increases the natural serotonin secretion.

See too

References

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