Lh and Melatonin Secretion Patterns in Pubertal Boys

Fevre, Michelle; Segel, Tamara; Marks, James F.; Boyar, Robert M.

doi:10.1210/jcem-47-6-1383

Cited by 34 publications

(9 citation statements)

References 8 publications

(1 reference statement)

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“…Our results confirm other reports that melatonin has a distinct circadian rhythm in children and adolescents [15,16]. Because there is a wide variation in amplitude and acrophase among individuals, studies based on melatonin concentrations in single timed blood samples may lead to equivocal conclu sions.…”

Section: Discussionsupporting

confidence: 85%

Evaluation of 5-Hydroxytryptophan Administration as a Test of Pineal Function in Humans

Cavallo¹,

Richards²,

Meyer³

et al. 1987

Horm Res

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We tested the hypothesis that acute 5-hydroxytryptophan (5-HTP) administration would cause an increase in concentrations of plasma melatonin to levels observed during the spontaneous nocturnal melatonin surge. We administered 5-HTP orally (5-12 mg/kg) to 10 healthy children and 5 healthy adults, and measured melatonin concentrations in plasma samples obtained every 30 min for 3-6 h. There was no appreciable increase in melatonin after 5-HTP stimulation, even though a melatonin increase has been reported in sheep treated with 5-HTP.

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Section: Discussionsupporting

confidence: 85%

Evaluation of 5-Hydroxytryptophan Administration as a Test of Pineal Function in Humans

Cavallo¹,

Richards²,

Meyer³

et al. 1987

Horm Res

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“…We did not find any statistical differences between sexes in the values of secretory parameters. Other investigators have also suggested that melatonin is secreted episodically in humans (6,22); however, the high diurnal melatonin concentrations re¬ ported in their studies, probably owing to a less specific assay than those presently available, make their conclusions questionable. Under our techni¬ cal conditions we were unable to detect a pulsatile diurnal pattern for melatonin secretion in adult volunteers, contrasting with the previous observa¬ tion by Weinberg et al (6).…”

Section: Discussionmentioning

confidence: 96%

“…In our study the melato¬ nin and LH pulsatile patterns were not superim¬ posable and did not show a clear statistical corre¬ lation, appearing as two independently regulated hormonal secretions. However, a decrease in the frequency of LH pulses between 03.00-05.00 h (30), the time when plasma melatonin rises to its maximal levels, has been described, with an inverse correlation between the integrated melatonin and LH levels; conversely, Fevre et al (22) have found a positive correlation between melatonin and LH secretion in 5 pubertal boys. Although no signifi¬ cant correlation was found in our study when the whole group was considered, three of the subjects (2 men and one woman) presented positive corre¬ lations between melatonin and LH plasma values.…”

Section: Discussionmentioning

confidence: 99%

Episodic nyctohemeral secretion of melatonin in adult humans: Lack of relation with LH pulsatile pattern

Leiva

Tortosa²,

Peinado³

et al. 1990

Acta Endocrinologica

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The concentration of melatonin and LH were determined in plasma samples obtained at 10-min intervals during 4 h of darkness (00.00-04.00 h) from 4 normal women, age 23-27 years, in the early follicular phase of the menstrual cycle and in 6 normal men, age 23-31 years. Additionally, melatonin concentration was determined in samples obtained from the men at 10-min intervals for 4 h during the day (10.00-14.00 h). A pulsatile pattern of melatonin secretion was found for all the subjects during darkness. There was no significant difference between women and men as to the number of pulses (2.8 \m=+-\0.5 vs 5.2 \ m=+-\1.0 per 4 h), amplitude of pulses (51.3 \ m=+-\28 vs 27.2 \m=+-\6 ng/l), concentration per 4 h (32.5 \m=+-\13 vs 31.0 \ m=+-\ 5 ng/l), or apparent half-life of melatonin (19.3 \m=+-\2.3 vs 15.3 \m=+-\7.5 min). The mean amplitude of the melatonin pulse correlated (r = 0.863, p<0.001) with the mean melatonin concentration per 4 h. A pulsatile LH secretion pattern was found for the 10 subjects and did not correlate significantly with the melatonin secretion pattern. The results are consistent with an independent signal for the demonstrated nyctohemeral pulsatile melatonin and LH secretions.The pineal gland is the main site of melatonin syn¬ thesis and secretion in humans (1,2). Plasma mela¬ tonin concentrations reflect faithfully pineal activ¬ ity (3,4). In mammals, melatonin shows a circadian pattern of synthesis and secretion entrained by the light-dark period, pineal activity being maximal during the dark period; thus, melatonin levels are low during the day and high at night (5). Studies carried out in healthy volunteers after frequent blood samples suggest that melatonin is secreted episodically (6,7). The variability of the reported results may be explained by differences in the fre¬ quency and hour of the sample collection, cycle analyses criteria, age of the subjects, and technical differences in the measurement of melatonin, among others. The apparent half-life (t'A) of cir¬ culating melatonin is also a matter of controversy, with no agreement in the data reported until now (7-9). Moreover, no physiological role has yet been defined for melatonin in humans. Although a strong influence of melatonin in the reproductive function in rodents (5) has been clearly established, there are no unequivocal data of this gonadal mod¬ ulation of melatonin in humans.The purpose of this work was to investigate the possibility of an episodic nature of melatonin se¬ cretion, to determine the apparent t'/b of endoge¬ nous melatonin, and to study the possible correla¬ tion of melatonin levels with LH surges in a group of healthy adult humans. Subjects and MethodsPlasma samples were obtained from 6 healthy men, aged 23 to 31 years and 4 healthy women, aged 23 to 27 years.Neither mean age (26.8 ± 1.82 vs 25.2 ± 1.7 years) (mean ± SEM), nor mean Body Mass Index (23 ± 1.8 vs 20.8 ± 2.0) were statistically different between sexes. Women were studied in the first half of the follicular phase of the menstrual cycle (4-8 days a...

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“…In man, the relationships between melatonin and the pituitary hormones are still contro versial. A correlation has been found by Fevre et al [1978] between the nocturnal rise of melatonin and LH in 4 boys (12-17 years old), whereas Vaughan et al [1978 described the lack of correlation between me latonin, LH, prolactin, ACTH, GH and sleep stages in 5 young men of 21 to 25 years old.…”

Section: Circadian Rhythm O F Plasma Melatoninmentioning

confidence: 99%

Some Aspects of the Orcadian Time Structure in the Elderly

Touitou¹

1982

Gerontology

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Rhythmicity is a fundamental property of living matter: biological rhythms in man as well as in other organisms can be demonstrated at all levels of organization (population, group, individual, organ, tissue, cell and subcellular structure). From a macroscopic point of view a rhythm implies regular periodicity of data displayed as a function of time. With the help of computers and special programs, it is possible to obtain a microscopic characterization and quantification of rhythm. A biorhythm can be characterized by the statistical estimation of several parameters: the period, the acrophase, the amplitude, the mesor. Each of these parameters is expressed as a mean with its confidence limits for a degree of security of 95%. With reference to the period, rhythms can be analyzed as a spectrum with several spectral domains: circadian rhythms (with period of about 24 h) are the most carefully studied, but other rhythms exist such as ultradian rhythms (period < 20 h) or infradian rhythms (period > 28 h, e.g. circamensual, circannual...). The acrophase is the peak time of the sine function used to approximate the rhythm. The amplitude is equal to half of the total rhythmic variability. The mesor is the mean adjusted rhythm; it corresponds to the 24-hour mean when sampling is performed at equal intervals. Circadian rhythms in blood variables are now fairly well documented in young healthy adults. Reports dealing with circadian rhythms in elderly subjects are few for obvious reasons, including the difficulty of gathering a group of elderly subjects comparable in age and social synchronization and moreover, free of major liver, heart, kidney, bone or any other degenerative disease and, consequently, not requiring medication. Therefore, we have undertaken a comparative study of the circadian rhythms in a group of 7 young healthy medical students (mean age 24 years) and in 18 elderly persons, free of the aforementioned diseases (mean age 80 years; 6 elderly men, 6 elderly women, 6 elderly women and men suffering from senile dementia). All subjects, either young or aged, were synchronized with respect to meal timing, diurnal activity and nocturnal rest. Blood samples were drawn at fixed times, every 4 h, during a single continuous span of 24 h beginning at 07.45 h (circadian rhythm) and the sampling was renewed four times a year to gather data on the circannual variations. Several biochemical variables were assayed, including electrolytes, enzymes, hormones. From these studies, it appears that the parameters characteristic of the biological rhythm may be modified with aging. However, the modifications are different from one function or variable to another. Differences in acrophases, mesors and amplitudes could be demonstrated. For instance, the acrophase may be shifted in the elderly for magnesium, calcium, proteins or some steroids, or on the contrary, it may be remarkably steady, e.g. for adrenal steroids, melatonin. The administration as a function of time of drugs or agents used as a diagnostic tool allowed to ascertain...

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Lh and Melatonin Secretion Patterns in Pubertal Boys

Cited by 34 publications

References 8 publications

Evaluation of 5-Hydroxytryptophan Administration as a Test of Pineal Function in Humans

Evaluation of 5-Hydroxytryptophan Administration as a Test of Pineal Function in Humans

Episodic nyctohemeral secretion of melatonin in adult humans: Lack of relation with LH pulsatile pattern

Some Aspects of the Orcadian Time Structure in the Elderly

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