Serotonin: Benefits, Reviews, Warnings?
Serotonin - also known as "feel-good hormone", 5-hydroxytryptamine or 5-HT - is a neurotransmitter synthesized in the brain and other tissues starting from ' essential amino acid tryptophan . SerotoninSerotonin is involved in many important biological functions, many of which are still to be clarified; In fact, like all chemical mediators, and various works by interacting with specific receptors , with completion of a different effect depending on the body region considered. We can then compare the serotonin to a key, which exert their action needs to interact with specific locks, represented by its receptors; the interaction between the key and locks allows the opening of doors that govern the control of brain and whole body.
As a precursor of melatonin , serotonin regulates circadian rhythms by synchronizing the sleep-wake cycle with endocrine daily fluctuations.
Serotonin is involved in the control of ' appetite and feeding behavior , leading to early onset of satiety , a lower intake of carbohydrates in favor of protein and a reduction, in general, the amount of food ingested. Not surprisingly, many people who complain about a drop in mood (eg, a pre-menstrual depression, see pre-menstrual syndrome ) experience a significant need for sweets (rich in simple carbohydrates) and chocolate (it contains and promotes the production of serotonin , because it is rich in simple sugars , as well as of psychoactive substances). Not surprisingly, therefore, some anorectic drugs useful in the treatment of ' obesity , such as fenfluramine , act by increasing the serotonin signal.
The ingestion of many carbohydrates stimulates the secretion of insulin , a hormone that facilitates the entry of nutrients into the cells, including amino acids with the exception of tryptophan. Consequently, after the massive insulin secretion in response to ' hyperglycemia , the relative levels of tryptophan in the blood rise (fall because those of the other amino acids). The relative increase in the tryptophan facilitates its passage in the central nervous system, where it increases the production of serotonin; what triggers a classic negative feed-back mechanism which reduces the desire to eat carbohydrates. By a similar mechanism, serotonin levels also increase during physical effort (which explains in part the antidepressant effects of physical activity); excessive increase of this substance during prolonged and strenuous effort is involved in the perception of fatigue .
After a meal rich in protein, tryptophan and therefore, the concentration of this amino acid in the blood increases, but did not change brain levels of serotonin. This lack of effect is due to the fact that, in parallel, increases in the blood also the concentration of other amino acids which, so to say, prevent the passage of tryptophan to the brain. For this reason, the intake of food containing tryptophan or a specific supplement not significantly increases the level of serotonin; Also the administration of the same is not possible because it is decomposed before it can produce its own effect.
In the cardiovascular system, serotonin acts on the contraction of the arteries , helping to control blood pressure ; also stimulates the contraction of smooth muscles of the bronchial tubes , the bladder and the large intracranial vessels (vasoconstriction of a massive cerebral arteries appears to trigger the ' migraine attack like excessive vasodilatation).
Serotinonergico The system is also involved in the control of sexual behavior and social relations (low serotonin levels seem to be linked to aggressive antisocial behavior and hypersexuality). No coincidence that some drugs that increase serotonin release and / or activity of its receptors, such as' ecstasy , induce euphoria, increased sociability and sense of self-esteem. In addition to the sexual behavior, serotonin has inhibitory effects on the sensitivity to pain, appetite and body temperature .
At the level of the CNS , after being released from the axon terminal, a part of serotonin interacts with postsynaptic receptors, while that in excess is degrata by MAO (monoamine oxidase) or reabsorbed (reuptake) from the presynaptic terminal, where it is stored in special vesicles. The drugs MAO inhibitors cause an irreversible blockade of monoamine oxidase , increasing the concentration of serotonin and other brain monoamines in the CNS; are therefore useful in the therapy of depression , although their use is now reduced to the important side effects. At the level of the central nervous system, serotonin present in the defect is, in fact decreases due to pathological mood; a lack of serotonin can then lead to depression, but also states of anxiety and aggression. Many antidepressants (such as Prozac ) work by blocking the reabsorption of serotonin, thus restoring and enhancing its signal, which is particularly low in depressed people; the same action is covered by ' St. John's Wort (or St John's wort) . Some of these medications at the same time increase the serotonin signal and that of noradrenaline (serotonergic and noradrenergic effect, typical of duloxetine and venlafaxine). Some medications increase the signal properties antiemicraniche serotonin (serotonergic receptor agonists are as sumatriptan), while other medicines taken for the same purpose have an opposite effect (pizotifen and methysergide)
Serotonin is also present in platelets , which stimulates the aggregation exerting vasoconstrictor activity and thrombogenic in response to injury of ' vascular endothelium (eg in response to a trauma).
Serotonin regulates motility and intestinal secretions , where the conspicuous presence of serotonin-containing enterochromaffin cells; causes diarrhea if present in excess and constipation if present at fault.
This action, in particular, is sensitive to the interrelationship between the "enteric nervous system" and the brain (central nervous system - CNS) and explains why very often have important psychophysical stress effects on intestinal motility . An excess of serotonin causes nausea and vomiting and not surprisingly this is one of the major side effects of several antidepressants, such as Prozac (nausea occurs in the first week of therapy and then regress); ondansetron, a drug that acts as an antagonist at serotonin receptors, on the other hand is a potent antiemetic (prevents the gag reflex is particularly strong during cycles of chemotherapy).
The existence of many drugs capable of interfering with the metabolism of serotonin effects in part by carrying out diversified depends, as mentioned, by the presence of the different receptors (there are at least 7 types), distributed in the various tissues of the body, and they interact with their active principles.