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Melatonin
Antioxidant and sleep promotor
Melatonin is a powerful antioxidant that can easily cross cell membranes and the blood-brain barrier. Unlike other antioxidants, melatonin does not undergo redox cycling, which is the ability of a molecule to undergo repeated reduction and oxidation. Redox cycling may allow other antioxidants (such as vitamin C) to act as pro-oxidants and promote free radical formation. Melatonin, once oxidized, cannot be reduced to its former state because it forms several stable end-products upon reacting with free radicals. Therefore, it has been referred to as a terminal (or suicidal) antioxidant.
Promoting better Sleep
Melatonin, taken right before sleep, helps to sleep sounder and better. A few milligrams will do the job, like 1 or 2 mg. It also improves the efficacy of other antioxidants. People short in melatonin many times are short in hGH as well, raising the risk for degenerative diseases such as osteroporosis.
Biogenic amines in the reduction of oxidative stress: Melatonin and its metabolites.
ReitNeuro Endocrinol Lett. 2008 Aug 4;29(4).
er RJ, Tan DX, Jou MJ, Korkmaz A, Manchester LC, Paredes SD.
Department of Cellular and Structural Biology, The University of Texas Health Science Center, San Antonio, Texas, USA. reiter@uthscsa.edu.
N-acetyl-5-methoxytryptamine (melatonin) is an endogenous indoleamine produced by all vertebrate organisms. Its production in the pineal gland has been extensively investigated but other organs also synthesize this important amine. Melatonin's functions in organisms are diverse. The actions considered in the current review relate to its ability to function in the reduction of oxidative stress, i.e., molecular damage produced by reactive oxygen and reactive nitrogen species. Numerous publications have now shown that not only is melatonin itself an efficient scavenger of free radicals and related reactants, but so are its by-products cyclic 3-hydroxymelatonin, N1-acetyl-N2-formyl-5-methoxykynuramine, and others. These derivatives are produced sequentially when each functions in the capacity of a free radical scavenger. These successive reactions are referred to as the antioxidant cascade of melatonin. That melatonin has this function within cells has been observed in studies employing time lapse conventional, confocal and multiphoton fluorescent microscopy coupled with the use of appropriate mitochondrial-targeted fluorescent probes.
The benefits of melatonin and its metabolites have been described in the brain where they are found to be protective in models of Parkinson's disease, Alzheimer's disease and spinal cord injury. The reader is reminded, however, that data not covered in this review has documented beneficial actions of these amines in every organ where they have been tested. The outlook for the use of melatonin in clinical trials looks encouraging given its low toxicity and high efficacy.
Melatonin helps reducing degenerative diseases, like osteoporosis
Osteoporis Int. 2008 Sep 3.
Nightshift work and fracture risk: the Nurses' Health Study.
Feskanich D, Hankinson SE, Schernhammer ES.
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA, USA, diane.feskanich@channing.harvard.edu.
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.
INTRODUCTION: We evaluated the association between nightshift work and fractures at the hip and wrist in postmenopausal nurses.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.
Thirty four years since the discovery of gastrointestinal melatonin.
Bubenik GA. J Physiol Pharmacol. 2008 Aug;59 Suppl 2:33-51.
Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada. gbubenik@uoguelph.ca
After the discovery of melatonin in the pineal gland by Lerner and co-workers in 1958, melatonin was also detected in the retina and the human appendix. Later, melatonin was confirmed immunohistologically in all segments of the gastrointestinal tract (GIT), in the guts of bovine embryos and in the GIT of low vertebrates. Melatonin was also confirmed in the pancreas and the hepatobiliary system. Melatonin is produced in the enteroendocrine cells of the GIT mucosa. The concentrations of melatonin in the GIT are 10-100x higher than in the plasma and the total amount of melatonin in the GIT is around 400x higher than the amount of melatonin in the pineal gland. Similar to pineal melatonin, GIT melatonin is a multifunctional compound which exhibits some general as well as some specific effects, depending on the organ and the location of GIT tissue. In the GIT, melatonin exhibits endocrine, paracrine, autocrine and luminal actions. Generally, the episodic secretion of melatonin from the GIT is related to the intake and digestion of food and to the prevention of tissue damage caused by hydrochloric acid and digestive enzymes. Some actions, such as the scavenging of hydroxyl free radicals, immunoenhancement and antioxidant effects are of general nature, whereas others, such as an increase of mucosal blood flow, the reduction of peristalsis and the regulation of fecal water content, are specific to the tubular GIT. Generally, melatonin actions oppose those of serotonin. Laboratory and clinical studies indicate that the utilization of melatonin can prevent or treat pathological conditions such as esophageal and gastric ulcers, pancreatitis, colitis, irritable bowel disease, and colon cancer.
Melatonin versus vitamin E as protective treatment against oxidative stress after extra-hepatic bile duct ligation in rats.
Journal of Pineal Research. 31(2):138-143, September 2001.
Montilla, P. 1; Cruz, A. 2; Padillo, F. J. 2; Tunez, I. 1; Gascon, F. 1; Munoz, M. C. 1; Gomez, M. 2; Pera, C. 2
Abstract: The aims of the present study were first to compare the effects of melatonin and vitamin E on the cholestasis syndrome and their protective effect on liver injury, and second, to evaluate the activity of antioxidant enzymes after treatment with these antioxidant drugs. Cholestasis was achieved in adult male Wistar rats by double ligature and section of the extra-hepatic biliary duct. Hepatic and plasma oxidative stress markers were evaluated by changes in the amount of lipid peroxides, measured as malondialdehyde (MDA) and reduced glutathione (GSH) in plasma and homogenates of hepatic tissue. Serum bilirubin, alkaline phosphatase (AP), and gamma-glutamyl-transpeptidase (GGT) were used to evaluate the severity of cholestasis, and serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were used to evaluate the hepatic injury. Both vitamin E and melatonin were administrated 1 day before and 7 days after bile duct ligation. Acute ligation of the bile duct was accompanied by a significant increased in MDA and a decrease in GSH levels in both plasma and liver, as well as a significant reduction in antioxidant enzymes activities. The overall analysis of both treatments showed that melatonin (500 [mu]g/kg daily) offered significantly better protection against cholestasis and a superior protective effect on hepatic injury than did vitamin E (15 mg/kg daily). Although vitamin E treatment resulted in a reduction of parameters of oxidative stress, the results were significantly better after a much lower daily dose of melatonin. Moreover, melatonin treatment was associated with a significant recovery of antioxidative enzymes. In conclusion, the present paper demonstrates a correlation between the intensity of biliary tract obstruction and increased free radical generation, as well as a direct correlation between the level of oxidative stress and the biochemical markers of liver injury. Melatonin (at a much lower dose than vitamin E) was much more efficient than vitamin E in reducing the negative parameters of cholestasis, the degree of oxidative stress and provided a significantly greater hepatoprotective effect against the liver injury secondary to the acute ligation of the biliary duct.
Studies:
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