Melatonin Abstracts Melatonin maintains mitochondrial membrane potential and attenuates activation of initiator (casp-9) and effector caspases (casp-3/casp-7) and PARP in UVR-exposed HaCaT keratinocytes T. W. Fischer, M. A. Zmijewski,J. Wortsman and A. Slominski, J. Pineal Res. 2008; 44:397–407 ABSTRACT Melatonin is a recognized antioxidant with high potential as a protective agent in many conditions related to oxidative stress such as neurodegenerative diseases, ischemia/reperfusion syndromes, sepsis and aging. These processes may be favorably affected by melatonin through its radical scavenging properties and/or antiapoptotic activity. Also, there is increasing evidence that these effects of melatonin could be relevant in keratinocytes, the main cell population of the skin where it would contribute to protection against damage induced by ultraviolet radiation (UVR). We therefore investigated the kinetics of UVR-induced apoptosis in cultured keratinocytes characterizing the morphological and mitochondrial changes, the caspases- dependent apoptotic pathways and involvement of poly(ADPribose) polymerase (PARP) activation as well as the protective effects of melatonin. When irradiated with UVB radiation (50 mJ/cm2), melatonin treated, cultured keratinocytes were more confluent, showed less cell blebbing, more uniform shape and less nuclear condensation as compared to irradiated, nonmelatonin-treated controls. Preincubation with melatonin also led to normalization of the decreased UVR-induced mitochondrial membrane potential. These melatonin effects were followed by suppression of the activation of mitochondrial pathway-related initiator caspase 9 (casp-9), but not of death receptor-dependent casp-8 between 24 and 48 hr after UVR exposure. Melatonin down-regulated effector caspases (casp-3/casp-7) at 24–48 hr post-UV irradiation and reduced PARP activation at 24 hr. Thus, melatonin is particularly active in UV-irradiated keratinocytes maintaining the mitochondrial membrane potential, inhibiting the consecutive activation of the intrinsic apoptotic pathway and reducing PARP activation. In conclusion, these data provide detailed evidence for specific antiapoptotic mechanisms of melatonin in UVR-induced damage of human keratinocytes. The cutaneous serotoninergic / melatoninergic system: securing a place under the sun
Andrzej Slominski, Jacobo Wortsman and Desmond J. Tobin, FASEB J. 19, 176-194 (2005) ABSTRACT It was recently discovered that mammalian skin can produce serotonin and transform it into melatonin. Pathways for the biosynthesis and biodegradation of serotonin and melatonin have been characterized in human and rodent skin and in their major cellular populations. Moreover, receptors for serotonin and melatonin receptors are expressed in keratinocytes, melanocytes, and fibroblasts and these mediate phenotypic actions on cellular proliferation and differentiation. Melatonin exerts receptor-independent effects, including activation of pathways protective of oxidative stress and the modification of cellular metabolism. While serotonin is known to have several roles in skin-e.g., proedema, vasodilatory, proinflammatory, and pruritogenic-melatonin has been experimentally implicated in hair growth cycling, pigmentation physiology, and melanoma control. Thus, the widespread expression of a cutaneous seorotoninergic/melatoninergic syste,m(s) indicates considerable selektivity of action to facilitate intra-, auto-, or paracrine mechanisms that define and influence skin function in a highly compartmentalized manner. Notably, the cutaneous melatoninergic system is organized to respond to continuous stimulation in contrast to the pineal gland, which (being insulated from the external environment) responds to discontinuous activation by the circadian clock. Overall, the cutaneous serotoninergic/melatoninergic system could counteract or buffer external (environmental) or internal stresses to preserve the biological integrity of the organ and to maintain its homeostasis. Constitutive and UV-induced metabolism of melatonin in keratinocytes and cell-free systems
Fischer T. W., Sweatman T. W., Semak L., Sayre R. M., Wortsman J. and Slominski A., FASEB J. 20, E897-E907 (2006) ABSTRACT Melatonin, which can be produced in the skin, exerts a protective effect against damage induced by UV radiation (UVR). We have investigated the effect of UVB, the most damaging component of UVR, on melatonin metabolism in HaCaT keratinocytes and in a cell-free system. Four metabolites were identified by HPLC and LC-MS: 6-hydroxymelatonin, N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK), 2- hydroxymelatonin (the main intermediate between melatonin and AFMK), and 4- hydroxymelatonin. Concentrations of these photoproducts were directly proportional to UVR-dose and to melatonin substrate content, and their accumulation was time-dependent. The UVR-dependent increase of AFMK and 2- hydroxymelatonin was also detected in keratinocytes, where it was accompanied by simultaneous consumption of intracellular melatonin. Of note, melatonin and its two major metabolites, 2- hydroxymelatonin and AFMK, were also detected in untreated keratinocytes, neither irradiated nor preincubated with melatonin. Thus, intracellular melatonin metabolism is enhanced under exposure to UVR. The additional biological activity of these individual melatonin metabolites increases the spectrum of potential actions of the recently identified cutaneous melatoninergic system. Melatonin reduces UV-induced reactive oxygen species in a dose-dependent manner in IL-3-stimulated leukocytes.
Fischer TW, Scholz G, Knoll B, Hipler UC, Elsner P., J Pineal Res. 2001 Aug;31(1):39-45. ABSTRACT Reactive oxygen species (ROS) are presumed to be involved in inflammatory UV reactions of the skin. This in vitro study was performed to investigate the suppressive effect of melatonin in interleukin-3 (IL-3) stimulated leukocytes. Neutrophilic granulocytes were isolated from EDTA-treated whole blood and placed in a phosphate-buffered saline (PBS) containing IL-3. Cell suspensions were either treated with PBS (control) or with increasing doses of melatonin (0.1, 0.5, 1, 2, 3, 5, 7.5, 10 mmol). One PBS solution was left unirradiated and the other nine solutions (PBS and melatonin) were irradiated with 750 mJ/cm2 UVB light (280-360 nm, max: 310 nm). Radical formation was measured by the chemiluminescence technique. UV- irradiated leukocytes showed a 5-fold higher radical formation than unirradiated leukocytes. Melatonin, in increasing doses in powers of ten, led to a maximum 030309 - 3 - suppression of free radicals at 10 nmol (P= 0.01) and 1 mmol melatonin (P= 0.001), showing a biphasic, non-linear, dose response relationship. Melatonin, given in amounts of 0.1-10 mmol, led to a direct dose-dependent suppression of ROS. Radical formation was suppressed significantly in a range from 0.5 to 10 mmol (P= 0.001). Melatonin is known to function as a radical scavenger and antioxidant; some of these melatonin effects may be receptor independent, while others may be receptor dependent. Melatonin suppresses reactive oxygen species induced by UV irradiation in leukocytes
Fischer TW, Scholz G, Knoll B, Hipler UC, Elsner P., J Pineal Res. 2004 Sep;37(2):107-12. ABSTRACT An investigation of the antioxidative UV protective effect of melatonin was performed in an in vitro irradiation model with leukocytes. Leukocytes were isolated from EDTA-treated whole blood and taken up in phosphate-buffered saline (PBS). Five of 10 aliquots were incubated with 2 mmol/L melatonin and 5 with PBS as a control. The samples were irradiated by UV light (280-360 nm, max: 310 nm) at doses between 75 and 300 mJ/cm(2) or left unirradiated. Radical formation was measured using the chemiluminescence
technique. Staining with trypan blue was performed to assess cell viability. Melatonin significantly suppressed radical formation in cell solutions irradiated from 75 to 300 mJ/cm(2) (P </= 0.001). Controls showed an increase of reactive oxygen species (ROS) formation as a sign of oxidative stress when irradiated with increasing UV doses and a maximum ROS formativ under 300 mJ/cm(2) UV light. The cytotoxicity of UV light was reduced by melatonin up to a UV dose of 1.5 J/cm(2). Leukocytes were suitable cells for the evaluation of the efficacy of melatonin as a radical scavenger under UV light. The results confirm that the clinically observed UV protective effects of melatonin may be at least partially based on its radical scavenging properties. Melatonin increases survival of HaCaT keratinocytes by suppressing UV-induced apoptosis
Fischer TW, Zbytek B, Sayre RM, Apostolov EO, Basnakian AG, Sweatman TW, Wortsman J, Elsner P, Slominski A., J Pineal Res. 2006 Jan;40(1):18-26. ABSTRACT Melatonin is a potent antioxidant and direct radical scavenger. As keratinocytes represent the major population in the skin and UV light causes damage to these cells, the possible protective effects of melatonin against UV-induced cell damage in HaCaT keratinocytes were investigated in vitro. Cells were preincubated with melatonin at graded concentrations from 10(-9) to 10(-3) m for 30 min prior to UV irradiation at doses of 25 and 50 mJ/cm2. Biological markers of cellular viability such as DNA synthesis and colony-forming efficiency as well as molecular markers of apoptosis were measured. DNA synthesis was determined by [3H]-thymidine incorporation into insoluble cellular fraction, clonogenicity through plating efficiency experiments and apoptosis by the terminal deoxynucleotidyl transferase-mediated dUTP nick- end labeling (TUNEL) assay. DNA synthesis experiments showed a strong protective effect by preincubation with melatonin at concentrations of 10(-4) m (P < 0.01) and 10(-3) m (P < 0.001). Additional postirradiation treatment with melatonin showed no increase in the pre-UV incubation protective effect. These results indicate that preincubation is a requirement for melatonin to exert its protective effects. The mechanism of melatonin's protective effect (10(-6) to 10(-3) m) includes inhibition of apoptosis as measured by TUNEL assay. Moreover, the biological significance of these effects is supported by clonogenic studies showing a significantly higher number of colonies in cultures treated with melatonin compared to controls. Thus, pretreatment with melatonin led to strong protection against UVB-induced damage in keratinocytes. HaCaT cell proliferation influenced by melatonin
Hipler U.C., Fischer T.W. and Elsner P., Skin Pharmacol Appl Skin Physiol, 16, 379-385 (2003) ABSTRACT The hormone melatonin is characterized by numerous pharmacological effects. The influence of melatonin on the growth of the human hair follicle was shown in previous investigations. In the present study, the effects of melatonin were investigated by means of proliferation tests of HaCaT keratinocytes using the [3H]thymidine incorporation, a fluorescence assay with Hoechst dye 33342 and the ATP bioluminescence assay. The aim of the study was to find melatonin concentrations suitable for treatments of the skin and whether there is a cytotoxic effect on HaCaT cells. The different proliferative activity of melatonin depending on its concentration and the time of incubation could be shown in all investigations.
A review of the evidence supporting melatonin's role as an antioxidant
Reiter R. J., Melchiorri D., Sewerynek E., Poeggeler B., Barlow-Walden L., J. Chuang J., Ortiz G. G., and Cuna- Castroviejo D., J Pineal Res 18, no. 1:1-11 (1995) ABSTRACT This survey summarizes the findings, accumulated within the last 2 years, concerning melatonin's role in defending against toxic free radicals. Free radicals are chemical constituents that have an unpaired electron in their outer orbital and, because of this feature, are highly reactive. Inspired oxygen, which sustains life, also is harmful because up to 5% of the oxygen (O2) taken in is converted to oxygen-free radicals. The addition of a single electron to O2 produces the superoxide anion radical (O2-.); O2-. Is catalytic-reduced by superoxide dismutase, to hydrogen peroxide (H2O2). Although H2O2 is not itself a free radical, it can be toxic at high concentrations and, more importantly, it can be reduced to the hydroxyl radical (.OH). The .OH is the most toxic of the oxygen-based radicals and it wreaks Harc within cells, particularly with macromolecules. In recent in vitro studies, melatonin was shown to be a very efficient neutralizer of the .OH; indeed, in the system used to test its free radical scavenging ability it was found to be significantly more effective than the well known antioxidant, glutatione (GSH), in doing so. Likewise, melatonin has been shown to stimulate glutathione peroxidase (GSHPx) activity in neural tissue; GSH-PX metabolizes reduced glutathione to its oxidized form and in doing so it converts H2O2 to H2O, thereby reducing generation of the .OH by eliminating its precursor. More recent studies have shown that melatonin is also a more efficient scavenger of the peroxyl radical than is vitamin E. The peroxyl radical is generated during lipid peroxidation and propagates the chain reaction that leads to massive lipid destruction in cell membranes. In vivo studies have demonstrated that melatonin is remarkably potent in protecting against free radical damage induced by a variety of means. Thus, DNA damage resulting from either the exposure of animals to the chemical karcinogen safrole or to ionizing radiation is markedly reduced when melatonin is co-administered. Likewise, the induction of cataracts, generally accepted as being a consequence of free radical attack on lenticular macromolecules, in newborn rats injected with a GSH-depleting drug are prevented when the animals are given daily melatonin injections. Also, paraquat- induced lipid peroxidation in the lungs of rats is overcome when they also receive melatonin during the exposure period. Paraquat is a highly toxic herbicide that inflicts at least part of its damage by generating free radicals. Chemical and physical properties and potential mechanisms: melatonin as a broad spectrum antioxidant and free radical scavenger
Tan DX, Reiter RJ, Manchester LC, Yan MT, El-Sawi M, Sainz RM, Mayo JC, Kohen R, Allegra M, Hardeland R., Curr Top Med Chem. 2002 Feb;2(2):181-97. ABSTRACT Melatonin was found to be a potent free radical scavenger in 1993. Since then over 800 publications have directly or indirectly confirmed this observation. Melatonin scavenges a variety of reactive oxygen and nitrogen species including hydroxyl radical, hydrogen peroxide, singlet oxygen, nitric oxide and peroxynitrite anion. Based on the analyses of structure-activity relationships, the indole moiety of the melatonin molecule is the reactive center of interaction with oxidants due to its high resonance stability and very low activation energy barrier towards the free radical reactions. However, the methoxy and amide side chains also contribute significantly to melatonin's antioxidant capacity. The NC=O structure in the C3 amide side chain is the functional group. The carbonyl group in the structure of N-C=O is key for melatonin to scavenge the second reactive species and the nitrogen in the N-C=O structure is necessary for melatonin to form the new five membered ring after melatonin's interaction with a reactive species. The methoxy group in C5 appears to keep melatonin from exhibiting prooxidative activity. If the methoxy group is replaced by a hydroxyl group, under some in vitro conditions, the antioxidant capacity of this molecule may be enhanced. However, the cost of this change are decreased lipophility and increased prooxidative
potential. Therefore, in in vivo studies the antioxidant efficacy of melatonin appears to be superior to its hydroxylated counterpart. The mechanisms of melatonin's interaction with reactive species probably involves donation of an elektron to form the melatoninyl cation radical or through an radical addition at the site C3. Other possibilities include hydrogen donation from the nitrogen atom or substitution at position C2, C4 and C7 and nitrosation. Melatonin also has the ability to repair damaged biomolecules as shown by the fact that it converts the guanosine radical to guanosine by electron transfer. Unlike the classical antioxidants, melatonin is devoid of prooxidative activity and all known intermediates generated by the interaction of melatonin with reactive species are also free radical scavengers. This phenomenon is defined as the free radical scavenging cascade reaction of the melatonin family. Due to this cascade, one melatonin molecule has the potential to scavenge up to 4 or more reactive species. This makes melatonin very effective as an antioxidant. Under in vivo conditions, melatonin is often several times more potent than vitamin C and E in protecting tissues from oxidative injury when compared at an equivalent dosage (micromol/kg). Future research in the field of melatonin as a free radical scavenger might be focused on: 1), signal transduction and antioxidant enzyme gene expression induced by melatonin and its metabolites, 2), melatonin levels in tissues and in cells, 3), melatonin structure modifications, 4), melatonin and its metabolites in plants and, 5), clinical trials using melatonin to treat free radiál related diseases such as Alzheimer's, Parkinson's, stroke and heart disease. Melatonin: a principal neuroimmunoregulatory and anti-stress hormone: its anti-aging effects.
Pierpaoli W, Maestroni GJ. Immunol Lett. 1987 Dec; 16(3-4):355-61 ABSTRACT Major environmental variables such as daily and seasonal changes of light and temperature regulace the daily circadian variations of synthesis and release of the pineal neurohormone N-acetyl-5- methoxytryptamine (melatonin). Melatonin has now been shown to be a potent immunoregulatory agent, and to be able to antagonize the immunosuppressive effects of acute anxiety stress in mice, as measured by antibody production, by thymus weight, and by the capacity of stressed- and mening melatonin-treated mice to react against a lethal virus. Both psychogenic factors and infectious agents such as viruses can act as "stressors" and induce an immunosuppression. Their combination is a determinant for the course of infectious diseases and, perhaps, cancer. Circadian (evening) melatonin possesses thus the singular ability to up-regulate the immunosuppression of stressed mice. This effect of melatonin is not exerted directly on immunocompetent cells, but mediated via the endogenous opioid system upon antigen-activation of T cells. Melatonin being a short-lived hormone with negligible side-effects which is rapidly degraded and eliminated by the body, the use of melatonin offers a new approach to the physiological control of stress and stress-related infectious diseases. In addition, melatonin could be used for the potentiation of primary immunization (vaccination) against antigens of the most varied nature which do not evoke a robust or longlasting secondary (memory) response. The regulatory function of pineal melatonin is discussed also in relation to hematopoiesis, to its oncostatic effects, and to its possible dual role in reproduction physiology and generation of immunocompetence and tolerance during ontogeny. Melatonin in the skin: synthesis,metabolism and functions
Andrzej Slominski, Desmond J. Tobin, Michal A. Zmijewski, Jacobo Wortsman and Ralf Paus, Trends in Endocrinology and Metabolism Vol. 1, Elsevier (Review 2007) Melatonin, a ubiquitous methoxyindole, is produced by and metabolized in the skin. Melatonin affects skin functions and structures through actions mediated by cell-surface and putative-nuclear receptors expressed in skin cells. Melatonin has both receptor-dependent and receptor-independent effects that protect against oxidative stress and can attenuate ultraviolet radiationinduced damage. The widespread expression and pleiotropic activity of the cutaneous melatoninergic system provides for a high level of cell-
specific selectivity. Moreover, intra-, auto- and para-crine mechanisms equip this system with exquisite functional selectivity. The properties of endogenous melatonin suggest that this molecule is an important effector of stress responses in the skin. In this way, melatonin actions may counteract or buffer both environmental and endogenous stressors to maintain skin integrity. Melatonin increases anagen hair rate in women with androgenetic alopecia or difuse alopecia: results of a pilot randomized controlled trial
T.W.FISCHER, G.BURMEISTER, * H.W.SCHMID* AND P.ELSNER Department of Dermatology and Allergology, Friedrich-Schiller-University, Erfurter Straße 35, D-07740 Jena, Germany, *ASAT Applied Science and Technology, Zug, Switzerland, British Journal of Dermatology 2004; 150: 341 -345 Summary Background In addition to the well-known hormonal influences of testosterone and dihydrotestosterone on the hair cycle, melatonin has been reported to have a beneficial effect on hair growth in animals. The effect of melatonin on hair growth in humans has not been investigated so far. Objectives To examine whether topically applied melatonin influences anagen and telogen hair rate in women with androgenetic or diffuse hair loss. Methods A double-blind, randomized, placebo-controlled study was conducted in 40 women suffering from diffuse alopecia or androgenetic alopecia. A 0,1% melatonin or a placebo solution was applied on the scalp once daily for 6 months and trichograms were performed to assess anagen and telogen hair rate. To monitor effects of treatment on physiological melatonin levels, blood samples were taken over the whole study period. Results Melatonin led to a significantly increased anagen hair rate in occipital hair in women with androgenetic hair loss compared with placebo (n = 12; P = 0.012). For frontal hair, melatonin gave a significant increase in the group with diffuse alopecia (n = 28; P = 0.046). The occipital hair samples of patients with diffuse alopecia and the frontal hair counts of those with androgenetic alopecia also showed an increase of anagen hair, but differences were not significant. Plasma melatonin levels increased under treatment with melatonin, but did not exceed the physiological night peak. Conclusions To the authors’ knowledge, this pilot study is the first to show that topically applied melatonin might influence hair growth in humans in vivo. The mode of action is not known, but the effect might result from an induction of anagen phase.
Overzicht Aandoeningen en Stofnamen in het kader van de Compensatieregeling Eigen Risico 2008 Verzekerden die lijden aan (een van de) onderstaande aandoeningen ontvangen een financiële compensatie voor het verplicht eigen risico. Dit geldt alleen wanneer zij minimaal 180 dagen per jaar een medicijn voorgeschreven krijgen voor één specifieke aandoening met daarin (een van de) stoffen d
Advance Access publication 24 December 2008Analgesic effects of treatments for non-specific low back pain:a meta-analysis of placebo-controlled randomized trialsL. A. C. Machado1, S. J. Kamper1, R. D. Herbert1, C. G. Maher1 and J. H. McAuley2Objective. Estimates of treatment effects reported in placebo-controlled randomized trials are less subject to bias than those estimatesprovided by other s