Mélatonine

See also: Melatonine

The mélatonine , often called hormone of the sleep , is the central Hormone of regulation of the rates/rhythms chronobiologic, and a certain point of view, practically the whole of hormonal secretions, at the man, all the mammals and seems it at the majority of the complex animal species.

This neurohormone is synthesized starting from a neuro-transmitter, the Sérotonine, which derive itself from the Tryptophane, an essential amino-acid. It is secreted by the pineal Body (in the Cerveau) in answer to the absence of light and can also be extracted from many plants, for example the Riz.

She is regarded by certain Biochimiste S as a paramount hormone, because she controls the secretion of the majority of the human hormones (Paracrine S and endocrine S). The mélatonine produced in pineal body acts like an endocrine hormone because it diffuses in the Sang, whereas the mélatonine produced by the retina acts like a hormone Paracrine.

The mélatonine would increase the libido (at the subjects of male sex) by an antagonism of the receivers of the serotonin of the type 5-HT (2A).

According to an Italian study, the Vin would comprise an significant amount of mélatonine at least, which would explain, partly, why certain people would be sleepy after the absorption of a more or less large quantity of wine.

Role

Biological clock

Julius Axelrod undertook many experiments to discover the role of the mélatonine and pineal body on the cycle of the sleep and the others circadian rates/rhythms.

In normal weather, the hormone of the sleep is secreted the night only (peak of secretion at 5 o'clock in the morning at the man, and on average, because its production is inhibited by the light) and it manages (partly) the circadian rates/rhythms. In the areas at very gray winter like Northern Europe, it is the fall of winter luminosity (short days and gray) which would start an overproduction of mélatonine generating a Asthénie, even a Déprime, which disappears in spring. Meetings of Luminothérapie can then make it possible to control the production of mélatonine.

Antioxydant

The mélatonine is powerful a Antioxydant which can easily pass the cellular walls or the hemato-encephalic Barrière. Contrary to other antioxydants (like the Vitamin C), the mélatonine is changeable, and once oxidized, it cannot be reduced directly to find its initial state.

Immune system

Associated with the Calcium, the mélatonine can also help with the immunizing response of the Lymphocytes T. Its medical use to increase the answer is subjected to controversy since it would also support the autoimmune diseases.

Rich foods in mélatonine

According to a study of the researchers of Health Science Center of the University of Texas, the Noix are an important source of mélatonine easily absorptive by the organization. After having compared the blood rate of nourished nut rats with that of normally nourished rats, the researchers noted that the nut consumption involved a multiplication by three of the blood rates of mélatonine. They think that the benefits of nuts rise from synergy between the mélatonine and the nutrients which they contain.

The mélatonine is also found in the Maïs, the Tomate S and the Potatoes, but in definitely lower quantities. The content of mélatonine several food still would be very known little about, according to the authors of the study.

The researchers are unable to say which quantity of nut should be daily consumed in order to benefit from its protective effects. But they affirm that because of the multitude of beneficial compounds that they contain, their consumption is definitely preferable with the catch of supplements of mélatonine. According to these researchers, it is thus preferable to take nuts, whose capacity to standardize the rates of mélatonine remains unknown, with supplements of mélatonine, whose therapeutic indications and effects are known. These researchers were paid by the Californian Commission of the nuts ( California Walnut Commission ).

Medical use

Proportioning and posology

The night secretion of mélatonine is implied in the release of the sleep. It has thus been used for a few years, in certain countries, to look after the sleep disorders (Insomnie S of the elderly, or the jet lag. With the E. - U. and with the Canada, for example, the mélatonine is on sale free. The suggested amounts are however very high. Victor Herbert, M.D., J.D., of the MT. The Sinai School off Medicine, off reviews several studies of Massachusetts Institute Technology which show that the supplements of mélatonine on sale free contain from 3 to 10 times more this hormone which it is not necessary to increase the quality of the sleep. These high amounts can even be against-productive: Lewy and colleagues give an experimental support for the idea, already widespread, that high amounts of mélatonine can exert an action which is propagated with phases which are not phases of answer to the mélatonine (" too much melatonin may spill over onto the wrong zone off the melatonin phase-response curve"). In this study, 0,5 Mg of mélatonine was effective, but not 20 Mg (40 times more).

On a practical level, 0,3 Mg (=300 mcg micrograms) represents a sufficient daily amount to readjust a circadian rate/rhythm out of phase; that implies that the mélatonine, for those which can get it, is much more accessible than one could have thought it. Contrary to a drug of the soporific type, the action of the mélatonine is not immediate (the effect being felt after 3 to 4 weeks of regulation approximately) and does not present side effects like habituation.

Pharmaceutical analogues of the mélatonine

Whereas the mélatonine is not largely recommended by the medical authorities, Ramelteon ( (S) - N (2 (1,6,7,8-tetrahydro-2H-indeno- (5,4) furan-8-yl) ethyl) propionamide ), sold under the name of Rozerem (property of Takeda Pharmaceuticals), which is conceived to activate the receivers of mélatonine MT1 and MT2, was approved for the treatment of insomnia in the United States.

Phototherapy

Rather than to give mélatonine in injection or food catch, doctors prefer in particular to treat the depression or some sleep disorder or rate/rhythm chronobiologic to expose their patients to a source of light close to that of the sun. It should be noted that the Vitamine D also depends on the exposure of the skin to the light.

Uses in veterinary medicine

The majority of the animals seem to produce mélatonine and/or to be sensitive there. The mélatonine is also a veterinary product which allows pregnancies any period of the year in mammals of breeding (goat…). The hens exposed to the light lay all the year, phenomenon induced by forced lighting.

Roles of the light and the darkness

The impact of the illumination on the Man is still badly measured, but it is noted that the blind men often suffer from sleep disorders. The daily catch of mélatonine one hour before laying down it would readjust their circadian rate/rhythm on the twenty-four hours cycle and thus would improve, even prevent, the sleep disorders. Studies let think that the children who slept with a lit lamp or an intrusive light in their room would be more numerous later at the risk myopia, but these studies were discussed.

Safety

The mélatonine is a priori not poison and without known side effect, except the Somnolence, so taken with high amount. The mélatonine Exogène does not affect normally its secretion Endogène, in the short or medium term. However, the catch of mélatonine associated with a Inhibiteur of the monoamine oxydases (IMAO) can cause a Overdose because the IMAO inhibit the metabolisation of the mélatonine by the organization.

A study of the department of Nutrition of the Andrews university indicates that some compressed of mélatonine would contain up to 10 times the amount necessary to cause the physiological effect on the level of mélatonine in blood to improve the night rest. According to this study, with these strong amounts, the mélatonine could cause Migraine S and sudden changes of mood and destabilize the hormonal balance of the organization (see Medical use , supra ).

Other known functions of the mélatonine

The mélatonine is also a powerful Antioxydant which can easily cross the cellular membranes and the hematoencephalic Barrière.

References

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