On the primary functions of melatonin in evolution: Mediation of photoperiodic signals in a unicell, photooxidation, and scavenging of free radicals*

Journal of Pineal Research, Год журнала: 1995, Номер 18(2), С. 104 - 111

Опубликована: Март 1, 1995

Abstract: Melatonin is widely abundant in many eukaryotic taxa, including vari‐ous animal phyla, angiosperms, and unicells. In the bioluminescent dinoflagellate Gonyaulax polyedra, melatonin produced concentrations sometimes exceed‐ing those found pineal gland, exhibits a circadian rhythm with pro‐nounced nocturnal maximum, mimics short‐day response of asexual encystment. Even more efficient as cyst inducer 5‐methoxytryptamine (5MT), which also periodically formed Gonyaulax. this unicell, photoperiodic signal‐transduction pathway presumably involves formation, its deace‐tylation to 5MT, 5MT‐dependent transfer protons from an acidic vacuole, cytoplasmic acidification. According concept, we observe that forma‐tion can be induced by various monoamine oxidase inhibitors protonophores, 5MT dramatically stimulates H + ‐dependent bioluminescence leads decrease pH, shown measurements dicyanohydroquinone fluorescence. Cellular components catalyze photooxidation melatonin. Its property being easily destroyed light presence cel‐lular catalysts may have been reason organisms developed mechanisms utilizing indoleamine mediator darkness. Photooxidative reactions melatonin, studied crude extracts and, de‐tail, protoporphyrin IX catalyst, lead formation N 1 ‐acetyl‐N ‐formyl‐5‐methoxykynuramine (AFMK) one main products. Photochemical involve interactions photooxidant cation radi‐cal leading melatonyl radical, subsequently combines superoxide anion. Photooxidation represents several possibilities general, biologically highly important act extremely radical scavenger, feature terminating reaction chains final combination su‐peroxide Trapping free radicals reflect primary evolutionar‐ily most ancient role living beings.

Язык: Английский

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Potent protective effect of melatonin on in vivo paraquat-induced oxidative damage in rats

Life Sciences, Год журнала: 1994, Номер 56(2), С. 83 - 89

Опубликована: Дек. 1, 1994

Язык: Английский

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Early neuropathological Alzheimer's changes in aged individuals are accompanied by decreased cerebrospinal fluid melatonin levels

Journal of Pineal Research, Год журнала: 2003, Номер 35(2), С. 125 - 130

Опубликована: Июль 23, 2003

Abstract: Neuropathology is the most reliable criterion for diagnosing Alzheimer's disease (AD). A well‐established system staging spread of neuropathological changes in AD available. The clinical use a biomarker that reflects change occurring brain tissue has not yet been established. Melatonin product plays only major role regulation circadian rhythms but may also exert neuroprotective effects AD. levels were determined ventricular postmortem cerebrospinal fluid (CSF) 121 subjects. Braak and modified cortex (MBSC) used to evaluate severity neuropathology. present study revealed stages AD, MBSC negatively correlated with CSF melatonin levels. By using MBSC, we now demonstrate first time significantly decreased aged individuals early temporal cortex, where process starts. Those did have any neurofibrillary tangle (NFT) or neuritic plaque (NP) had much higher (287 ± 68 280 64 pg/mL, respectively) than those few NFTs NPs (82 4 39 8 cortex. These results suggest decrease be an event development possibly even before symptoms.

Язык: Английский

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Comparative analysis of the protective effects of melatonin and vitamin E on streptozocin‐induced diabetes mellitus

Journal of Pineal Research, Год журнала: 2002, Номер 32(4), С. 225 - 230

Опубликована: Апрель 30, 2002

There is a clearly documented link between diabetic complications and lipid peroxidation. Hyperglycemia causes reduction in levels of protective endogenous antioxidants increases generation free radicals. The present study was carried out to compare the effects melatonin vitamin E against streptozocin (STZ)‐induced diabetes rats. Melatonin administered s.c. (100 μ g/kg) whereas given i.p. mg/kg) after induction with STZ (60 mg/kg). Plasma total cholesterol, triglyceride low density lipoprotein (LDL) were increased group while both injection caused significant decrease all these parameters. lowering effect greater than that E. brain, liver kidney tissue malondialdehyde (MDA) which because STZ‐induced diabetes. Vitamin also reduced elevated MDA concentrations rat tissues, but more potent Furthermore, treatment rats brain glutathione peroxidase (GSH‐Px) activity below control found be less effective on GSH‐Px it liver. In summary, prevents many by reducing oxidative stress protects organisms from damage dyslipidemia. Considering much lower molar concentration compared E, seems antioxidant, especially kidney.

Язык: Английский

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Maternal‐fetal transfer of melatonin in pregnant women near term

Journal of Pineal Research, Год журнала: 1998, Номер 25(3), С. 129 - 134

Опубликована: Ноя. 1, 1998

Abstract: Our objective was to evaluate the maternal‐fetal transfer of melatonin in pregnant women. Serum concentration measured by high‐performance liquid chromatography with electrochemical detection a maternal vein and umbilical artery at time birth. Blood samples were obtained from 12 women who had spontaneously delivered vaginally night. A single oral dose administered each 33 patients underwent cesarean section, and. blood taken 1,2, 3, or 4 hr after administration delivery. Cesarean section performed between 1300 1500 hr. The mean concentrations peripheral venous arterial did not differ significantly, positive correlations serum levels observed three sources blood. 3 mg led marked increases melatonin, maximum 2 (21.84 ± 2.09 ng/ml) drug administration. Changes resembled those found vein. significantly veins. closely correlated (r = 0.924, ( P < 0.001). These results suggest that, humans, is transferred fetal circulation both easily rapidly. potential for therapeutic use as an antioxidant exists preeclampsia.

Язык: Английский

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