Category Archives: Melatonin

Melatonin Implants Influence Bone Repair in Rabbits


Melatonin promotes angiogenesis during repair of bone defects: a radiological and histomorphometric study in rabbit tibiae.

The pineal gland hormone, melatonin, is an immunomodulator and neuroendocrine hormone; it also stimulates monocyte, cytokine and fibroblast proliferations, which influence angiogenesis. The aim of this study was to investigate the effects of melatonin on angiogenesis during bone defect repair by means of radiological and histomorphometric evaluations of bone response to melatonin implants.
Twenty New Zealand rabbits weighing 3,900-4,500 g were used. Twenty melatonin implants were inserted in the proximal metaphyseal area of the animals’ right tibia and 20 control areas were located in the left proximal metaphyseal area. Following implantation, the animals were sacrificed in groups of five, after 1, 2, 3 and 4 weeks, respectively. Anteroposterior and lateral radiographs were taken, and radiographic thermal imaging analysis was performed for all groups at different time stages following implant insertion. Samples were sectioned at 5 μm and stained using Hematoxylin-Eosin and Masson’s trichrome, supplementing radiographic findings with histomorphometric analysis.
After 4 weeks, radiological images showed complete repair of the bone defects. No healed or residual bone alterations attributable to the presence of the melatonin implant were observed. Histomorphometric analysis at 4 weeks showed the presence of a higher density newly formed bone. There were statistically significant differences in the length of cortical formation between the melatonin group and the control group during the first weeks of the study; there were also statistically significant differences in the number of vessels observed in the melatonin groups at the first two study stages.
Melatonin may have potential beneficial effects on bone defect repair.

Ramírez-Fernández MP, Calvo-Guirado JL, de-Val JE, Delgado-Ruiz RA…
Clin Oral Investig Jan 2013
PMID: 22323056

Melatonin Induces Bone Sialoprotein In Vitro


Melatonin regulates human bone sialoprotein gene transcription.

Melatonin is produced by the pineal gland and regulates various physiological processes including osteoblast differentiation and bone formation. Bone sialoprotein (BSP) is a mineralized connective tissue-specific protein expressed in the early stage of cementum and bone mineralization. To elucidate the effects of melatonin on human BSP gene expression, we utilized human Saos2 osteoblast-like cells. Melatonin (100 nM) increased the level of BSP mRNA at 3 h, and the level became maximal at 12 and 24 h. We then investigated the melatonin-induced transcriptional activity of luciferase constructs (between -84LUC and -868LUC) including different lengths of the human BSP gene promoter transfected into Saos2 cells. The effects of melatonin abrogated in constructs included 2-bp mutations in the two cAMP response elements (CRE1 and CRE2). The effects of melatonin were suppressed by protein kinase A, tyrosine kinase, ERK1/2 and phosphatidylinositol 3-kinase inhibitors. Gel mobility shift assays showed that melatonin increased the binding of nuclear proteins to CRE1 and CRE2, and antibodies against CRE binding protein 1 (CREB1), phospho-CREB1, c-Fos, c-Jun, JunD and Fra2 disrupted CRE1 and CRE2 protein complex formation. These data indicate that melatonin induces BSP transcription via the CRE1 and CRE2 elements in the human BSP gene promoter.

Matsumura H, Ogata Y
J Oral Sci 2014
PMID: 24739710 | Free Full Text

Melatonin Benefits Bones in Old Rats


Melatonin dietary supplement as an anti-aging therapy for age-related bone loss.

Introduction: Previous studies have shown that melatonin, an antioxidant molecule secreted from the pineal gland, is a positive regulator of bone mass. However, melatonin potential effects on bone mass have never been investigated in old population yet. The aim of this study was to assess the effects of dietary melatonin supplementation on mass accrual and biomechanical properties of old rat femora. Methods: Twenty 22-months-old male Wistar rats were divided into 2 randomly assigned groups. The first group was treated for 10 weeks with melatonin, whereas the second group left untreated (control). Rat femurs were collected, and their phenotypes and biomechanical properties were investigated by micro-computed tomography, histomorphometry and 3-point-bending test. Statistical analyses were performed by Student’s two-tailed unpaired t-test. In all experiments, a value of p < 0.05 was considered significant. Results: Rats treated with melatonin had higher bone volume, bone trabecular number, trabecular thickness and cortical thickness in comparison to control group. Histomorphometric analyses confirmed the increase of bone volume in melatonin-treated rats. In agreement with these findings, melatonin-treated rats demonstrated with higher bone stiffness, flexural modulus and ultimate load compared to controls. Conclusion: These compelling results are the first evidence indicating that dietary melatonin supplementation is able to exert beneficial effects against age-related bone loss in old rats; improving the microstructure and biomechanical properties of aged bones.

Tresguerres IF, Tamimi F, Eimar H, Barralet J…
Rejuvenation Res Mar 2014
PMID: 24617902

Review: Melatonin Induces Osteoblastogenesis and Inhibits Osteoclastogenesis


Melatonin effects on bone: potential use for the prevention and treatment for osteopenia, osteoporosis, and periodontal disease and for use in bone-grafting procedures.

An important role for melatonin in bone formation and restructuring has emerged, and studies demonstrate the multiple mechanisms for these beneficial actions. Statistical analysis shows that even with existing osteoporotic therapies, bone-related disease, and mortality are on the rise, creating a huge financial burden for societies worldwide. These findings suggest that novel alternatives need to be developed to either prevent or reverse bone loss to combat osteoporosis-related fractures. The focus of this review describes melatonin’s role in bone physiology and discusses how disruption of melatonin rhythms by light exposure at night, shift work, and disease can adversely impact on bone. The signal transduction mechanisms underlying osteoblast and osteoclast differentiation and coupling with one another are discussed with a focus on how melatonin, through the regulation of RANKL and osteoprotegerin synthesis and release from osteoblasts, can induce osteoblastogenesis while inhibiting osteoclastogenesis. Also, melatonin’s free-radical scavenging and antioxidant properties of this indoleamine are discussed as yet an additional mechanism by which melatonin can maintain one’s bone health, especially oral health. The clinical use for melatonin in bone-grafting procedures, in reversing bone loss due to osteopenia and osteoporosis, and in managing periodontal disease is discussed.

Maria S, Witt-Enderby PA
J. Pineal Res. Dec 2013
PMID: 24372640

Hypothesis: Melatonin for Osteoporosis


Is postmenopausal osteoporosis related to pineal gland functions?

There is currently considerable interest in the pathogenesis of postmenopausal osteoporosis, which is the most common metabolic bone disease. Osteoporosis affects approximately 20 million persons in the United States, 90% of whom are postmenopausal women. Although there is evidence that estrogen deficiency is an important contributory factor, the pathogenesis of osteoporosis is multifactorial and presently poorly understood. There is evidence that pineal melatonin is an anti-aging hormone and that the menopause is associated with a substantial decline in melatonin secretion and an increased rate of pineal calcification. Animal data indicate that pineal melatonin is involved in the regulation of calcium and phosphorus metabolism by stimulating the activity of the parathyroid glands and by inhibiting calcitonin release and inhibiting prostaglandin synthesis. Hence, the pineal gland may function as a “fine tuner” of calcium homeostasis. In the following communication, we propose that the fall of melatonin plasma levels during the early stage of menopause may be an important contributory factor in the development of postmenopausal osteoporosis. Consequently, plasma melatonin levels taken in the early menopause could be used as an indicator or perhaps as a marker for susceptibility to postmenopausal osteoporosis. Moreover, light therapy, administration of oral melatonin (2.5 mg at night) or agents which induce a sustained release of melatonin secretion such as 5-methoxypsoralen, could be useful agents in the prophylaxis and treatment of postmenopausal osteoporosis. Finally, since application of external artificial magnetic fields has been shown to synchronize melatonin secretion in experimental animals and humans, we propose that treatment with artificial magnetic fields may be beneficial for postmenopausal osteoporosis.

Sandyk R, Anastasiadis PG, Anninos PA, Tsagas N
Int. J. Neurosci. Feb 1992
PMID: 1305608

Nightshift Work Associated with Fractures


Nightshift work and fracture risk: the Nurses’ Health Study.

Nightshift work suppresses melatonin production and has been associated with an increased risk of major diseases including hormonally related tumors. Experimental evidence suggests that light at night acts through endocrine disruption likely mediated by melatonin. To date, no observational study has addressed the effect of night work on osteoporotic fractures, another condition highly sensitive to sex steroid exposure. Our study, to our knowledge, the first to address this question, supports the hypothesis that nightshift work may negatively affect bone health, adding to the growing list of ailments that have been associated with shift work.
We evaluated the association between nightshift work and fractures at the hip and wrist in postmenopausal nurses.
The study population was drawn from Nurses’ Health Study participants who were working full or part time in nursing in 1988 and had reported their total number of years of rotating nightshift work. Through 2000, 1,223 incident wrist and hip fractures involving low or moderate trauma were identified among 38,062 postmenopausal women. We calculated multivariate relative risks (RR) of fracture over varying lengths of follow-up in relation to years of nightshift work.
Compared with women who never worked night shifts, 20+ years of nightshift work was associated with a significantly increased risk of wrist and hip fractures over 8 years of follow-up [RR = 1.37, 95% confidence interval (CI), 1.04-1.80]. This risk was strongest among women with a lower body mass index (<24) who never used hormone replacement therapy (RR = 2.36; 95% CI, 1.33-4.20). The elevated risk was no longer apparent with 12 years of follow-up after the baseline single assessment of nightshift work.
Long durations of rotating nightshift work may contribute to risk of hip and wrist fractures, although the potential for unexplained confounding cannot be ruled out.

Feskanich D, Hankinson SE, Schernhammer ES
Osteoporos Int Apr 2009
PMID: 18766292

Melatonin May Protect Against Bone Loss in Postmenopausal Women


Assessment of the relationship between circadian variations of salivary melatonin levels and type I collagen metabolism in postmenopausal obese women.

Few experimental and clinical studies show that melatonin (MEL) can play a significant part to modulate circadian bone metabolism. On this basis it was suggested that MEL secretion which altered during 24-h in obese women could be of importance to regulate bony mass defect after menopause.
The aim of the study was to prove if there were any connection between changes in 24-h profile of serum MEL levels and circadian metabolism of type I collagen in postmenopausal women with visceral obesity.
The relationship of 24-h profile of salivary MEL and circadian metabolism of type I collagen (as assessed by measuring saliva concentrations of carboxyterminal propeptide of type I procollagen–PICP and cross-linked carboxyterminal telopeptide of type I collagen–ICTP) was investigated in 26 women with visceral obesity (33.5 < BMI < 42.1 kg/m(2)) and 18 healthy volunteers with correct body mass (21 < BMI < 24.5 kg/m(2); 0.73 < WHR < 0.76). The specimens were collected at subjects’ home at 3 h intervals during a 24 h span. The age range of all subjects was 52-60 years.
In all the obese women studied a tendency to suppress circadian levels of tested biochemical markers of bone metabolism was observed (especially regarding ICTP); those alterations were accompanied by substantial increment in MEL concentrations during the day. Significant and negative correlation was found between values of acrophase MEL and PICP rhythms and both amplitude and acrophase of MEL and ICTP rhythms.
Our results confirm hypothesis that alterations in MEL concentrations might have a protective effect against postmenopausal loss of bone mass.

Ostrowska Z, Kos-Kudla B, Marek B, Swietochowska E…
Neuro Endocrinol. Lett. Apr 2001
PMID: 11335888

Review: Melatonin Effects on Bone – 2003


Melatonin effects on bone: experimental facts and clinical perspectives.

Bone formation proceeds through a remodeling process that runs continuously, involving the resorption of old bone by osteoclasts, and the subsequent formation of new bone by osteoblasts. This is controlled by growth factors and cytokines produced in bone marrow microenvironment and by the action of systemic hormones, like parathyroid hormone, estradiol or growth hormone (GH). One candidate for hormonal modulation of osteoblast and osteoclast formation is melatonin. Because circulating melatonin declines with age, its possible involvement in post-menopausal and senescence osteoporosis is considered. This review article discusses early studies on melatonin-bone relationships and recent data that suggest a direct effect of melatonin on bone. Melatonin could act as an autacoid in bone cells as it is present in high quantities in bone marrow, where precursors of bone cells are located. Melatonin dose-dependently augmented proteins that are incorporated into the bone matrix, like procollagen type I c-peptide. Osteoprotegerin, an osteoblastic protein that inhibits the differentiation of osteoclasts is also augmented by melatonin in vitro. Another possible target cell for melatonin is the osteoclast, which degrades bone partly by generating free radicals. Melatonin through its free radical scavenger and antioxidant properties may impair osteoclast activity and bone resorption. At least in one study melatonin was both inhibitory to osteoclastic and osteoblastic cells. Therefore, the documented bone-protecting effect of melatonin in ovariectomized rats can depend in part on the free radical scavenging properties of melatonin. Additionally, melatonin may impair development of osteopenia associated with senescence by improving non-rapid eye movement sleep and restoring GH secretion. Whether melatonin can be used as a novel mode of therapy for augmenting bone mass in diseases deserves to be studied.

Cardinali DP, Ladizesky MG, Boggio V, Cutrera RA…
J. Pineal Res. Mar 2003
PMID: 12562498

Review: Melatonin Effects on Bones and Teeth


Melatonin effects on hard tissues: bone and tooth.

Melatonin is an endogenous hormone rhythmically produced in the pineal gland under the control of the suprachiasmatic nucleus (SCN) and the light/dark cycle. This indole plays an important role in many physiological processes including circadian entrainment, blood pressure regulation, seasonal reproduction, ovarian physiology, immune function, etc. Recently, the investigation and applications of melatonin in the hard tissues bone and tooth have received great attention. Melatonin has been investigated relative to bone remolding, osteoporosis, osseointegration of dental implants and dentine formation. In the present review, we discuss the large body of published evidence and review data of melatonin effects on hard tissues, specifically, bone and tooth.

Liu J, Huang F, He HW
Int J Mol Sci 2013
PMID: 23665905 | Free Full Text

From the full text:

Bone remolding processes are mediated by hormones, cytokines, growth factors and other molecules [22]. One of the hormones modulating bone formation and resorption is melatonin. It is hypothesized that melatonin, perhaps through three principle actions, modulates bone metabolism. Firstly, melatonin directly affects the actions of osteoblast and osteoclast. Numerous studies documented that melatonin increases pre-osteoblast/osteoblast/osteoblast-like cell proliferation, promotes the expression of type I collagen and bone marker proteins (e.g., alkaline phosphatase, osteopontin, bone sialoprotein and osteocalcin), and stimulates the formation of a mineralized matrix in these cells [23–27]. Besides, melatonin inhibits the differentiation of osteoclasts via decreases in the expression of RANK mRNA and increases in both the mRNA and protein levels of osteo-protegerin [28,29]. Secondly, melatonin indirectly regulates bone metabolism through the interaction with systemic hormones (e.g., PTH, calcitonin, and estrogen) or other moleculars. Ladizesky et al. [15] revealed that estradiol treatment could prolong the effect of melatonin to augment bone remodeling in ovariectomized rats; it indicates that appropriate circulating estradiol levels might be needed for melatonin effects on bone. Thirdly, osteoclasts generate high levels of superoxide anions during bone resorption that contribute to the degradative process. Melatonin is a significant free-radical scavenger and antioxidant. It can clear up the free radicals generated by osteoclast during the bone resorption process and protect bone cells from oxidative attacks [18,30,31].


Some studies revealed the possible etiologic role of melatonin in osteoporosis. Nocturnal plasma melatonin levels decline with age. It has also been reported that melatonin secretion decreases sharply during menopause, which is associated with post-menopausal osteoporosis [46,47]. A correlation between decreased plasma melatonin levels and an increased incidence of bone deterioration as seen in post-menopausal women has been examined [48]. Furthermore, Ostrowska et al. [49] found that a pinealectomy in rats promotes the induction of bone metabolism biomarkers. In addition, Feskanich et al. [50] reported that twenty or more years of nightshift work significantly increased the risk of wrist and hip fractures in post-menopausal women. Nightshift work leads to disturbances of melatonin secretion as well as severe circadian rhythm disruption. These observations taken together suggest that melatonin may be involved in the pathogenesis of osteoporosis.

Melatonin Increases Bone Density in Blind Mice


Effects on bone by the light/dark cycle and chronic treatment with melatonin and/or hormone replacement therapy in intact female mice.

In this study, the effects of the light/dark cycle, hormone replacement therapy (HRT), and nocturnal melatonin supplementation on osteogenic markers and serum melatonin levels were examined in a blind mouse model (MMTV-Neu transgenic mice). Melatonin levels in this mouse strain (FVB/N) with retinal degeneration (rd-/-) fluctuate in a diurnal manner, suggesting that these mice, although blind, still perceive light. Real-time RT-PCR analyses demonstrated that Runx2, Bmp2, Bmp6, Bglap, and Per2 mRNA levels coincide with melatonin levels. The effect of chronic HRT (0.5 mg 17β-estradiol + 50 mg progesterone in 1800 kcal of diet) alone and in combination with melatonin (15 mg/L drinking water) on bone quality and density was also assessed by histomorphometry and microcomputed tomography, respectively. Bone density was significantly increased (P < 0.05) after 1 yr of treatment with the individual therapies, HRT (22% increase) and nocturnal melatonin (20% increase) compared to control. Hormone replacement therapy alone also increased surface bone, decreased trabecular space, and decreased the number of osteoclasts without affecting osteoblast numbers compared to the control group (P < 0.05). Chronic HRT + melatonin therapy did not significantly increase bone density, even though this combination significantly increased Bglap mRNA levels. These data suggest that the endogenous melatonin rhythm modulates markers important to bone physiology. Hormone replacement therapy with or without nocturnal melatonin in cycling mice produces unique effects on bone markers and bone density. The effects of these therapies alone and combined may improve bone health in women in perimenopause and with low nocturnal melatonin levels from too little sleep, too much light, or age.

Witt-Enderby PA, Slater JP, Johnson NA, Bondi CD…
J. Pineal Res. Nov 2012
PMID: 22639972