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See detailApproche statistique de l'influence de l'age et du sexe sur l'excretion de 6-sulfatoxymelatonine urinaire (a-MT6s) chez l'individu normal
Hendrick, J. C.; Crasson, Marion ULg; Hagelstein, Marie-Thérèse ULg et al

in Annales d'Endocrinologie (2002), 63(1), 3-7

A radioimmunoassay of urinary 6-sulphatoxymelatonin (a-MT6s) was performed in 90 normal subjects: 44 males and 46 females (17-67 years). Patients treated with betablokers or antidepressants were not ... [more ▼]

A radioimmunoassay of urinary 6-sulphatoxymelatonin (a-MT6s) was performed in 90 normal subjects: 44 males and 46 females (17-67 years). Patients treated with betablokers or antidepressants were not included in this study. Urine samples were collected over three periods of time: 7 to 11 p.m., 11 p.m. to 7 a.m., and 7 to 11 a.m. Between 11 p.m. and 7 a.m., the subjects slept in their normal environment and had not ingested alcohol for 24 hours. We searched for a possible relation between urinary a-MT6s excretion (expressed in ng/l/h) and age. From 7 to 11 p.m. and from 7 to 11 a.m. no significant relation could be found. On the contrary, between 11 p.m. and 7 a.m. there was a significant relation indicating decrease of a-MT6s secretion with increasing age. Several linear or non-linear curve patters were tested: Boltzmann sigmoid (1(st), 2(nd), and 3(rd) degree), polynomial curves. The Boltzmann sigmoid showed the best fit judging by the r-squared value (0.152) and the runs test (p=0.64). On this curve the inflection point was located at 53 4 years (SDM, standard deviation of the mean). From 19 to 45 years, the upper sigmoid plateau was located at 1381 91 ng/l/h (SDM). The decrease was found between 45 and 60 years and the lower sigmoid plateau then stabilized at 467 370 ng/l/h (\SDM). In the study group, there was no significant difference between men and women according to the Mann-Withney test. Finally, use of oral contraceptives did not affect urinary a-MT6s (Mann-Withney). [less ▲]

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See detailMelatonine. II. Actions physiologiques et therapeutiques
Bruls, E.; Crasson, Marion ULg; Van Reeth, O. et al

in Revue Médicale de Liège (2000), 55(9), 862-70

Melatonin is a hormone mainly secreted by the pineal gland during the dark phase of the light-dark cycle. The most known function of melatonin in mammals is to transmit information concerning light-dark ... [more ▼]

Melatonin is a hormone mainly secreted by the pineal gland during the dark phase of the light-dark cycle. The most known function of melatonin in mammals is to transmit information concerning light-dark cycles playing the role of an active neuroendocrine transducer of environmental information. Given this chronobiologic role of pineal melatonin, it seems to be useful in the management of shift work, jet lag and some sleep disorders. In vitro like in vivo melatonin seems to be effective as an antioxidant and oncostatic agent. Melatonin may provide protection against aging process, degenerative diseases, cancer and play a role also in sexual maturation, reproduction, immune function and psychiatric illness. The administration of melatonin in the jet-lag syndrome is well codified. Further clinical research is needed for a better understanding and definition of other indications, treatment regimens and safety of the hormone. The aim of this paper is to review the current knowledge on its clinical implications. [less ▲]

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See detailMelatonine. I. Physiologie de la secretion
Bruls, E.; Crasson, Marion ULg; Legros, Jean-Jacques ULg

in Revue Médicale de Liège (2000), 55(8), 785-92

Melatonin is a hormone mainly secreted by the pineal gland during the dark phase of the light-dark cycle. The best known function of melatonin in mammals is to transmit information concerning light-dark ... [more ▼]

Melatonin is a hormone mainly secreted by the pineal gland during the dark phase of the light-dark cycle. The best known function of melatonin in mammals is to transmit information concerning light-dark cycles playing the role of an active neuroendocrine transducer of environmental information. Although melatonin circadian rhythm is endogenous, based on 25 hour cycles, it is modulated by light-dark cycle. During the day, the light signal is sent to the pineal gland through a special neuronal pathway and inhibits melatonin secretion. During the night, the last neuron of this pathway which is coming from the cervical ganglion superior releases nonadrenalin in the interstitium. Nonadrenalin stimulates melatonin synthesis through cAMP accumulation. Some factors other than light can also influence melatonin levels. Electromagnetic fields, age, male sex, Cushing syndrome, hypogonadotrophic hypogonadism, alcoholism seem to be associated with lower melatonin secretion. Female sex, hypergonadotrophic hypogonadism, sport and fasting seem to be linked to higher melatonin secretion. Some pathologies and drugs can modulate some steps of the neuroanatomic pathway of melatonin synthesis. Stress has no effect. The influence of weight and height is still investigated. Once released, melatonin can act on different organs through specific receptors (retina, supra-chiasmatic nucleus, hypophysis, brain, blood vessels, digestive tract, ovaries). [less ▲]

Detailed reference viewed: 53 (2 ULg)