N-acetyl-5-methoxytryptamine (Melatonin), as a crucial messenger in plants, functions in adjusting biological rhythms, stress tolerance, plant growth and development. Several studies have shown the retardation effect of exogenous melatonin treatment on plant growth and development. However, the in vivo role of melatonin in regulating plant leaf growth and the underlying mechanism are still uncl...

Aging alters many aspects of circadian rhythmicity, including responsivity to phase-shifting stimuli and the amplitude of the rhythm of melatonin secretion. As melatonin is both an output from and an input to the circadian clock, we hypothesized that the decreased melatonin levels exhibited by old hamsters may adversely impact the circadian system as a whole. We enhanced the diurnal rhythm of m...

BACKGROUND/AIMS Small intestinal neuroendocrine tumours (SI-NETs) are derived from enterochromaffin cells. After demonstrating melatonin in enterochromaffin cells, we hypothesized that SI-NETs may express and secrete melatonin, which may have an impact on clinical factors and treatment response. METHODS Tumour tissue from 26 patients with SI-NETs, representing paired sections of primary tumou...

Melatonin has been reported to suppress adrenocorticotropin (ACTH) secretion in the anterior pituitary and cortisol production in the adrenal by different mechanisms. However, the effect of melatonin on aldosterone production has remained unknown. In this study, we investigated the role of melatonin in the regulation of aldosterone production using human adrenocortical H295R cells by focusing o...

Melatonin is a key hormone in the regulation of circadian rhythms of vertebrates, including songbirds. Understanding diurnal melatonin fluctuations and being able to reverse or simulate natural melatonin levels are critical to investigating the influence of melatonin on various behaviors such as singing in birds. Here we give a detailed overview of natural fluctuations in plasma melatonin conce...

Introduction ▼ Melatonin is a hormone produced by the pineal gland, regulating the circadian rhythm in mammals [1]. Exogenous administration of melatonin improves sleep quality [2], reduces jet lag [3], and possesses analgesic [4, 5], anti-oxidative [6, 7] and anti-inflammatory effects [6]. Melatonin is traditionally administered orally, but the drug displays a poor and variable bioavailability...

Here, we report the effects of short exposure to melatonin on the human mt1 (h mt1) melatonin receptor-mediated signaling in Chinese hamster ovary (CHO) cells, and the consequences of an exposure that resembles the physiological pattern of melatonin release on cAMP-mediated signal transduction. Short exposure (10 min) of h mt1 melatonin receptors to melatonin (400 pM) inhibited forskolin-stimul...

In this study, serum melatonin and urinary 6-sulfatoxymelatonin (aMT6s) were measured in 14 major depressive inpatients, compared to 14 matched controls according to age, gender, season and hormonal treatment in women. Moreover, the relationship between serum melatonin and urinary aMT6s levels was analysed in the two groups. Results indicated that the two groups of subjects showed a clear melat...

PROBLEM This study investigates dose-dependent effects of melatonin on ovarian graft. METHOD OF STUDY Vitrified-thawed whole ovaries of newborn mice were grafted into ovariectomized mature ones. Melatonin (20, 50, 100, and 200 mg/kg/day) was administrated to separate groups of host mice for 32 days. IgM and IgG antibodies, Th1 and Th2 cytokines, and melatonin in recipient's blood were measure...

In bile duct-ligated (BDL) rats, large cholangiocytes proliferate by activation of cAMP-dependent signaling. Melatonin, which is secreted from pineal gland as well as extrapineal tissues, regulates cell mitosis by interacting with melatonin receptors (MT1 and MT2) modulating cAMP and clock genes. In the liver, melatonin suppresses oxidative damage and ameliorates fibrosis. No information exists...