The circadian rhythm of melatonin in hypothyroidism and hyperthyroidism

Soszyński, P; Zgliczyński, S; Pucilowska, Jolanta B.

doi:10.1530/acta.0.1190240

Cited by 102 publications

(207 citation statements)

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“…It has been observed in thyrotoxic human subjects that the levels of melatonin and thyroid hormones are negatively correlated (Soszynski et al ., 1988), although increased melatonin secretion has been reported in hypothyroid patients (Rojdmark et al ., 1991). A positive correlation between melatonin and TSH has been observed in both normal subjects (Rao & Mager, 1987) and hypothyroid patients (Soszynski et al ., 1988). Although a recent study demonstrated that the administration of exogenous melatonin has no effect on the spontaneous release of TSH in men (Terzolo et al ., 1990) and women (Terzolo et al ., 1993).…”

Section: Discussionmentioning

confidence: 99%

Effects of exogenous melatonin on pituitary hormones in humans

Iwatani

Tomoda

et al. 2001

Clinical Physiology

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The effects of melatonin on physiological function remain unclear, although the therapeutic potential of melatonin is being increasingly recognized. The aim of the present study is to investigate the effects of exogenous melatonin on the spontaneous release of pituitary hormone in humans. A double blind placebo-controlled protocol was designed to examine 12 adult healthy volunteers and 12 sleep disorder patients who have been treating with low doses of melatonin for 1 year. Either exogenous melatonin or placebo of 1 mg was given at 09:00 hours, followed by the collection of blood samples every 20 min for 4 h. Each blood sample was examined for levels of serum melatonin, PRL, LH, FSH, GH and TSH. LH levels were higher in sleep disorder patients compared with the healthy volunteers. In other pituitary hormones, there were no significant difference between healthy adults and sleep disorder patients. In all subjects, PRL levels were stimulated by acute administration of 1 mg of exogenous melatonin, while the levels of other pituitary hormones were not affected. These results suggested that exogenous melatonin can affect the spontaneous release of LH and PRL in humans. In addition, we demonstrated that 1-year oral melatonin treatment did not affect the responses to the acute administration of melatonin.

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Section: Discussionmentioning

confidence: 99%

Effects of exogenous melatonin on pituitary hormones in humans

Iwatani

Tomoda

et al. 2001

Clinical Physiology

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“…However, even the clearest examples of multiple periodic SRs exhibit seemingly irregular additional changes in the light curves (Kerschbaum, Lebzelter & Lazaro 2001;Lebzelter & Kiss 2001), so that multimode pulsation with stationary frequency and amplitude content does not fully explain the light variations in SRs. Other explanations suggested in the literature include chaotic phenomena (Icke, Frank & Heske 1992;Buchler, Kolláth & Cadmus 2004), coupling of rotation and pulsation (Barnbaum, Morris & Kahane 1995;Soszynski et al 2004) and dust-shell dynamics (Höfner, Feuchtinger & Dorfi 1995;Höfner et al 2003). Studies of radial velocity variability in SRs (Lebzelter, Kiss & Hinkle 2000;Lebzelter & Hinkle 2002) suggested that light variations are dominated by stellar pulsations, which implies that the observed irregularities must be largely related to stochastic behaviour of the oscillations.…”

Section: Introductionmentioning

confidence: 99%

The light curve of the semiregular variable L2 Puppis -- II. Evidence for solar-like excitation of the oscillations

Bedding

Kiss

Kjeldsen

et al. 2005

Monthly Notices of the Royal Astronomical Society

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We analyse visual observations of the pulsations of the red giant variable L2 Puppis (L2 Pup). The data cover 77 yr between 1927 and 2005, thus providing an extensive empirical base for characterizing properties of the oscillations. The power spectrum of the light curve shows a single mode resolved into multiple peaks under a narrow envelope. We argue that this results from stochastic excitation, as seen in solar oscillations, with a mode lifetime of about 5 yr. The random fluctuations in phase also support this idea. A comparison with X Cam, a true Mira star with the same pulsation period, and W Cyg, a true semiregular star, illustrates the basic differences in phase behaviours. The Mira shows very stable phase, consistent with excitation by the κ‐mechanism, whereas W Cyg shows large phase fluctuations that imply stochastic excitation. We find L2 Pup to be intermediate, implying that both mechanisms play a role in its pulsation. Finally, we also checked the presence of low‐dimensional chaos and could safely exclude it.

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“…32 Nevertheless, it was also reported that melatonin levels measured in the day and at night in hypothyroidism patients were not different from those in the controls. 33,34 Consequently, it can be said that there is no consensus in the studies exploring the relation between hypothyroidism and melatonin.…”

Section: Resultsmentioning

confidence: 99%

The relation between reduced serum melatonin levels and zinc in rats with induced hypothyroidism

Belviranlı

Baltacı

2007

Cell Biochemistry & Function

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The objective of the study was to explore the changes in melatonin and zinc levels in rats with induced hypothyroidism. Thirty adult male rats used in the study were allocated to three groups with equal numbers. Group 1: General control group which was not subjected to any procedure. Group 2: Sham-hypothyroidism group to which was administered 10 mg kg(-1) intraperitoneal (i.p.) physiologic saline (0.09% NaCl) for 4 weeks. Group 3: Hypothyroidism group which was supplemented with intraperitoneal 10 mg kg(-1) propylthiouracil (PTU) for 4 weeks. Blood samples collected from all animals at the end of the study by decapitation were analysed for serum Total T4 (TT4), Total T3 (TT3), Free T4 (FT4), Free T3 (FT3) (ELISA) as well as for melatonin (RIA) hormones and zinc levels (atomic emission). Comparison of the study groups in terms of thyroid hormones, melatonin and zinc levels showed that TT4, TT3, FT4, FT3, melatonin and zinc levels in group 3 were lower than those in groups 1 and 2 (p < 0.01). These parameters were not different in groups 1 and 2. The results of the study demonstrate that PTU supplementation for 4 weeks results in a significant inhibition in both melatonin and zinc levels. Inhibited melatonin levels may result from the decrease in zinc levels.

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The circadian rhythm of melatonin in hypothyroidism and hyperthyroidism

Cited by 102 publications

References 0 publications

Effects of exogenous melatonin on pituitary hormones in humans

Effects of exogenous melatonin on pituitary hormones in humans

The light curve of the semiregular variable L2 Puppis -- II. Evidence for solar-like excitation of the oscillations

The relation between reduced serum melatonin levels and zinc in rats with induced hypothyroidism

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