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Panigrahi AK, Pal PK, Sarkar Paria D. Melatonin as an Ameliorative Agent Against Cadmium- and Lead-Induced Toxicity in Fish: an Overview. Appl Biochem Biotechnol 2024:10.1007/s12010-023-04723-3. [PMID: 38224395 DOI: 10.1007/s12010-023-04723-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/15/2023] [Indexed: 01/16/2024]
Abstract
Diverse anthropogenic activities and lack of knowledge on its consequences have promoted serious heavy metal contaminations in different aquatic systems throughout the globe. The non-biodegradable nature of most of these toxic heavy metals has increased the concern on their possible bioaccumulation in aquatic organisms as well as in other vertebrates. Among these aquatic species, fish are most sensitive to such contaminated water that not only decreases their chance of survivability in the nature but also increases the probability of biomagnifications of these heavy metals in higher order food chain. After entering the fish body, heavy metals induce detrimental changes in different vital organs by impairing multiple physiological and biochemical pathways that are essential for the species. Such alterations may include tissue damage, induction of oxidative stress, immune-suppression, endocrine disorders, uncontrolled cell proliferation, DNA damage, and even apoptosis. Although uncountable reports have explored the toxic effects of different heavy metals in diverse fish species, but surprisingly, only a few attempts have been made to ameliorate such toxic effects. Since, oxidative stress seems to be the underlying common factor in such heavy metal-induced toxicity, therefore, a potent and endogenous antioxidant with no side effect may be an appropriate therapeutic solution. Apart from summarizing the toxic effects of two important toxicants, i.e., cadmium and lead in fish, the novelty of the present treatise lies in its arguments in favor of using melatonin, an endogenous free radical scavenger and indirect antioxidant, in ameliorating the toxic effects of heavy metals in any fish species.
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Affiliation(s)
- Ashis Kumar Panigrahi
- The University of Burdwan, Burdwan, West Bengal, 713104, India
- Eco-toxicology, Fisheries & Aquaculture Extension Laboratory, Department of Zoology, University of Kalyani, Kalyani, West Beng, al-741235, India
| | - Palash Kumar Pal
- Oxidative Stress and Free Radical Biology Laboratory, Department of Physiology, University of Calcutta, 92, A.P.C. Road, Kolkata, 700009, India
| | - Dipanwita Sarkar Paria
- Department of Zoology, Chandernagore College, The University of Burdwan, Chandernagore, West Beng, al-712136, India.
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Wu X, Li P, Tao J, Chen X, Zhang A. Subchronic Low-Dose Methylmercury Exposure Accelerated Cerebral Telomere Shortening in Relevant with Declined Urinary aMT6s Level in Rats. TOXICS 2023; 11:191. [PMID: 36851065 PMCID: PMC9961034 DOI: 10.3390/toxics11020191] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
Methylmercury (MeHg) is a global pollutant with established toxic effects on the central nervous system (CNS). However, early events and early-warning biomarkers of CNS damage following exposure to low-dose MeHg are still lacking. This study aimed to investigate whether subchronic low-dose MeHg exposure had adverse effects on the cerebral telomere length, as well as serum melatonin and its urinary metabolite 6-sulfatoxymelatonin (aMT6s) in rats. Sixteen male Sprague Dawley rats were divided into two groups. Group I was the control group. In group II, rats were exposed to MeHg by gavage at a dose of 0.1 mg/kg/day for 3 months. This study revealed that MeHg exposure resulted in impairment of learning and memory ability, a slightly reduced number of neurons and an irregular arrangement of neurons in the hippocampus. It also significantly accelerated telomere shortening in the cerebral cortex, hippocampus and hypothalamus. Moreover, MeHg exposure decreased the levels of melatonin in serum and aMT6s in urine, partly by suppressing the synthesis of 5-hydroxytryptamine (5-HT) in the brain but promoted the expression of melatonin-catalyzing AANAT and ASMT. Importantly, cerebral telomere length was positively correlated with MT and aMT6s after MeHg exposure. These results suggested that the shortened telomere length in the brain may be an early event in MeHg-induced CNS toxicity, and the level of aMT6s in urine may serve as an early-warning biomarker for MeHg-induced CNS damage.
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Affiliation(s)
- Xi Wu
- The Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, School of Public Health, Guizhou Medical University, Guiyang 550025, China
| | - Ping Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Junyan Tao
- The Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, School of Public Health, Guizhou Medical University, Guiyang 550025, China
| | - Xiong Chen
- The Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, School of Public Health, Guizhou Medical University, Guiyang 550025, China
| | - Aihua Zhang
- The Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, School of Public Health, Guizhou Medical University, Guiyang 550025, China
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Melatonin: A Versatile Protector against Oxidative DNA Damage. Molecules 2018; 23:molecules23030530. [PMID: 29495460 PMCID: PMC6017920 DOI: 10.3390/molecules23030530] [Citation(s) in RCA: 160] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 02/13/2018] [Accepted: 02/22/2018] [Indexed: 12/15/2022] Open
Abstract
Oxidative damage to DNA has important implications for human health and has been identified as a key factor in the onset and development of numerous diseases. Thus, it is evident that preventing DNA from oxidative damage is crucial for humans and for any living organism. Melatonin is an astonishingly versatile molecule in this context. It can offer both direct and indirect protection against a wide variety of damaging agents and through multiple pathways, which may (or may not) take place simultaneously. They include direct antioxidative protection, which is mediated by melatonin's free radical scavenging activity, and also indirect ways of action. The latter include, at least: (i) inhibition of metal-induced DNA damage; (ii) protection against non-radical triggers of oxidative DNA damage; (iii) continuous protection after being metabolized; (iv) activation of antioxidative enzymes; (v) inhibition of pro-oxidative enzymes; and (vi) boosting of the DNA repair machinery. The rather unique capability of melatonin to exhibit multiple neutralizing actions against diverse threatening factors, together with its low toxicity and its ability to cross biological barriers, are all significant to its efficiency for preventing oxidative damage to DNA.
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Romero A, Ramos E, de Los Ríos C, Egea J, Del Pino J, Reiter RJ. A review of metal-catalyzed molecular damage: protection by melatonin. J Pineal Res 2014; 56:343-70. [PMID: 24628077 DOI: 10.1111/jpi.12132] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 03/11/2014] [Indexed: 12/31/2022]
Abstract
Metal exposure is associated with several toxic effects; herein, we review the toxicity mechanisms of cadmium, mercury, arsenic, lead, aluminum, chromium, iron, copper, nickel, cobalt, vanadium, and molybdenum as these processes relate to free radical generation. Free radicals can be generated in cells due to a wide variety of exogenous and endogenous processes, causing modifications in DNA bases, enhancing lipid peroxidation, and altering calcium and sulfhydryl homeostasis. Melatonin, an ubiquitous and pleiotropic molecule, exerts efficient protection against oxidative stress and ameliorates oxidative/nitrosative damage by a variety of mechanisms. Also, melatonin has a chelating property which may contribute in reducing metal-induced toxicity as we postulate here. The aim of this review was to highlight the protective role of melatonin in counteracting metal-induced free radical generation. Understanding the physicochemical insights of melatonin related to the free radical scavenging activity and the stimulation of antioxidative enzymes is of critical importance for the development of novel therapeutic strategies against the toxic action of these metals.
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Affiliation(s)
- Alejandro Romero
- Departamento de Toxicología y Farmacología, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain
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5
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Karadayian AG, Bustamante J, Czerniczyniec A, Cutrera RA, Lores-Arnaiz S. Effect of melatonin on motor performance and brain cortex mitochondrial function during ethanol hangover. Neuroscience 2014; 269:281-9. [PMID: 24713372 DOI: 10.1016/j.neuroscience.2014.03.062] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 03/28/2014] [Accepted: 03/28/2014] [Indexed: 12/13/2022]
Abstract
Increased reactive oxygen species generation and mitochondrial dysfunction occur during ethanol hangover. The aim of this work was to study the effect of melatonin pretreatment on motor performance and mitochondrial function during ethanol hangover. Male mice received melatonin solution or its vehicle in drinking water during 7 days and i.p. injection with EtOH (3.8 g/kg BW) or saline at the eighth day. Motor performance and mitochondrial function were evaluated at the onset of hangover (6h after injection). Melatonin improved motor coordination in ethanol hangover mice. Malate-glutamate-dependent oxygen uptake was decreased by ethanol hangover treatment and partially prevented by melatonin pretreatment. Melatonin alone induced a decrease of 30% in state 4 succinate-dependent respiratory rate. Also, the activity of the respiratory complexes was decreased in melatonin-pretreated ethanol hangover group. Melatonin pretreatment before the hangover prevented mitochondrial membrane potential collapse and induced a 79% decrement of hydrogen peroxide production as compared with ethanol hangover group. Ethanol hangover induced a 25% decrease in NO production. Melatonin alone and as a pretreatment before ethanol hangover significantly increased NO production by nNOS and iNOS as compared with control groups. No differences were observed in nNOS protein expression, while iNOS expression was increased in the melatonin group. Increased NO production by melatonin could be involved in the decrease of succinate-dependent oxygen consumption and the inhibition of complex IV observed in our study. Melatonin seems to act as an antioxidant agent in the ethanol hangover condition but also exhibited some dual effects related to NO metabolism.
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Affiliation(s)
- A G Karadayian
- Instituto de Bioquímica y Medicina Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, C1113AAD Buenos Aires, Argentina
| | - J Bustamante
- Instituto de Bioquímica y Medicina Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, C1113AAD Buenos Aires, Argentina
| | - A Czerniczyniec
- Instituto de Bioquímica y Medicina Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, C1113AAD Buenos Aires, Argentina
| | - R A Cutrera
- Laboratorio de Neurobiología y Ritmos, Facultad de Medicina, Universidad de Buenos Aires, C1113AAD Buenos Aires, Argentina
| | - S Lores-Arnaiz
- Instituto de Bioquímica y Medicina Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, C1113AAD Buenos Aires, Argentina.
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Christinal J, Sumathi T. Effect of Bacopa monniera extract on methylmercury-induced behavioral and histopathological changes in rats. Biol Trace Elem Res 2013; 155:56-64. [PMID: 23872736 DOI: 10.1007/s12011-013-9756-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 07/04/2013] [Indexed: 11/28/2022]
Abstract
Methylmercury (MeHg) is a well-recognized environmental contaminant with established health risk to human beings by fish and marine mammal consumption. Bacopa monniera (BM) is a perennial herb and is used as a nerve tonic in Ayurveda, a traditional medicine system in India. This study was aimed to evaluate the effect of B. monniera extract (BME) on MeHg-induced toxicity in rat cerebellum. Male Wistar rats were administered with MeHg orally at a dose of 5 mg/kg b.w. for 21 days. Experimental rats were given MeHg and also administered with BME (40 mg/kg, orally) 1 h prior to the administration of MeHg for 21 days. After treatment period, MeHg exposure significantly decreases the body weight and also caused the following behavioral changes. Decrease tail flick response, longer immobility time, significant decrease in motor activity, and spatial short-term memory. BME pretreatment reverted the behavioral changes to normal. MeHg exposure decreases the DNA and RNA content in cerebellum and also caused some pathological changes in cerebellum. Pretreatment with BME restored all the changes to near normal. These findings suggest that BME has a potent efficacy to alleviate MeHg-induced toxicity in rat cerebellum.
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Affiliation(s)
- Johnson Christinal
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu, India
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Karadayian A, Mac Laughlin M, Cutrera R. Estrogen blocks the protective action of melatonin in a behavioral model of ethanol-induced hangover in mice. Physiol Behav 2012; 107:181-6. [DOI: 10.1016/j.physbeh.2012.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/19/2012] [Accepted: 07/15/2012] [Indexed: 12/23/2022]
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Protective Effect of Bacopa monniera on Methyl Mercury-Induced Oxidative Stress in Cerebellum of Rats. Cell Mol Neurobiol 2012; 32:979-87. [DOI: 10.1007/s10571-012-9813-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/04/2012] [Indexed: 01/21/2023]
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9
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Korbas M, MacDonald TC, Pickering IJ, George GN, Krone PH. Chemical form matters: differential accumulation of mercury following inorganic and organic mercury exposures in zebrafish larvae. ACS Chem Biol 2012; 7:411-20. [PMID: 22026432 DOI: 10.1021/cb200287c] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mercury, one of the most toxic elements, exists in various chemical forms each with different toxicities and health implications. Some methylated mercury forms, one of which exists in fish and other seafood products, pose a potential threat, especially during embryonic and early postnatal development. Despite global concerns, little is known about the mechanisms underlying transport and toxicity of different mercury species. To investigate the impact of different mercury chemical forms on vertebrate development, we have successfully combined the zebrafish, a well-established developmental biology model system, with synchrotron-based X-ray fluorescence imaging. Our work revealed substantial differences in tissue-specific accumulation patterns of mercury in zebrafish larvae exposed to four different mercury formulations in water. Methylmercury species not only resulted in overall higher mercury burdens but also targeted different cells and tissues than their inorganic counterparts, thus revealing a significant role of speciation in cellular and molecular targeting and mercury sequestration. For methylmercury species, the highest mercury concentrations were in the eye lens epithelial cells, independent of the formulation ligand (chloride versusl-cysteine). For inorganic mercury species, in absence of l-cysteine, the olfactory epithelium and kidney accumulated the greatest amounts of mercury. However, with l-cysteine present in the treatment solution, mercuric bis-l-cysteineate species dominated the treatment, significantly decreasing uptake. Our results clearly demonstrate that the common differentiation between organic and inorganic mercury is not sufficient to determine the toxicity of various mercury species.
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Affiliation(s)
- Malgorzata Korbas
- Molecular and Environmental
Science Research Group, Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2,
Canada
| | - Tracy C. MacDonald
- Molecular and Environmental
Science Research Group, Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2,
Canada
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK, S7N 5B3,
Canada
| | - Ingrid J. Pickering
- Molecular and Environmental
Science Research Group, Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2,
Canada
| | - Graham N. George
- Molecular and Environmental
Science Research Group, Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2,
Canada
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK, S7N 5B3,
Canada
- Department of Anatomy
and Cell
Biology, University of Saskatchewan, Saskatoon,
SK, S7N 5E5, Canada
| | - Patrick H. Krone
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK, S7N 5B3,
Canada
- Department of Anatomy
and Cell
Biology, University of Saskatchewan, Saskatoon,
SK, S7N 5E5, Canada
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Attenuation by methyl mercury and mercuric sulfide of pentobarbital induced hypnotic tolerance in mice through inhibition of ATPase activities and nitric oxide production in cerebral cortex. Arch Toxicol 2007; 82:343-53. [DOI: 10.1007/s00204-007-0255-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Accepted: 10/16/2007] [Indexed: 12/15/2022]
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Tan DX, Manchester LC, Di Mascio P, Martinez GR, Prado FM, Reiter RJ. Novel rhythms of N1-acetyl-N2-formyl-5-methoxykynuramine and its precursor melatonin in water hyacinth: importance for phytoremediation. FASEB J 2007; 21:1724-9. [PMID: 17314136 DOI: 10.1096/fj.06-7745com] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
N1-acetyl-N2-formyl-5-methoxykynuramine (AMFK) is a major metabolite of melatonin in mammals. To investigate whether AFMK exists in plants, an aquatic plant, water hyacinth, was used. To achieve this, LC/MS/MS with a deuterated standard was employed. AFMK was identified in any plant for the first time. Both it and its precursor, melatonin, were rhythmic with peaks during the late light phase. These novel rhythms indicate that these molecules do not serve as the chemical signal of darkness as in animals but may relate to processes of photosynthesis or photoprotection. These possibilities are supported by higher production of melatonin and AFMK in plants grown in sunlight (10,000-15,000 microW/cm2) compared to those grown under artificial light (400-450 microW/cm2). Melatonin and AFMK, as potent free radical scavengers, may assist plants in coping with harsh environmental insults, including soil and water pollutants. High levels of melatonin and AFMK in water hyacinth may explain why this plant more easily tolerates environmental pollutants, including toxic chemicals and heavy metals and is successfully used in phytoremediation. These novel findings could lead to improvements in the phytoremediative capacity of plants by either stimulating endogenous melatonin synthesis or by adding melatonin to water/soil in which they are grown.
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Affiliation(s)
- Dun-Xian Tan
- Department of Cellular Structural Biology, The University of Texas Health Science Center, 7703 Floyd Curl Dr., San Antonio, TX 78229, USA
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Kobal AB, Horvat M, Prezelj M, Briski AS, Krsnik M, Dizdarevic T, Mazej D, Falnoga I, Stibilj V, Arneric N, Kobal D, Osredkar J. The impact of long-term past exposure to elemental mercury on antioxidative capacity and lipid peroxidation in mercury miners. J Trace Elem Med Biol 2004; 17:261-74. [PMID: 15139389 DOI: 10.1016/s0946-672x(04)80028-2] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Limited information is available on the effects of chronic mercury exposure in relation to the risk of cardiovascular disease (CVD). It is known from in vitro and in vivo studies that Hg can promote lipid peroxidation through promotion of free radical generation, and interaction with antioxidative enzymes and reduction of bioavailable selenium. The objective of the study was to test the hypothesis that long-term past occupational exposure to elemental Hg (Hg0) can modify antioxidative capacity and promote lipid peroxidation in miners. The study population comprised 54 mercury miners and 58 workers as the control group. The miners were examined in the post-exposure period. We evaluated their previous exposure to Hg0, the putative appearance of certain nonspecific symptoms and signs of micromercurialism, as well as the main behavioural and biological risk factors for CVD, and determined: 1) Hg and Se levels in blood and urine, 2) antioxidative enzymes, Cu/Zn superoxide dismutase (CuZn-SOD), catalase (CAT), and selenoenzyme glutathione peroxidase (GSH-Px) activity in erythrocytes as indirect indices of free radical activity, 3) pineal hormone melatonin (MEL) in blood and urine, and 4) lipid hydroperoxides (LOOHs) and malondialdehyde (MDA) as lipid peroxidation products. The mercury miners were intermittently exposed to Hg0 for periods of 7 to 31 years. The total number of exposure periods varied from 13 to 119. The cumulative U-Hg peak level varied from 794-11,365 microg/L. The current blood and urine Hg concentrations were practically on the same level in miners and controls. Miners showed some neurotoxic and nephrotoxic sequels of micromercurialism. No significant differences in behavioural and biological risk factors for CVD were found between miners and controls. A weak correlation (r = 0.36, p < 0.01) between systolic blood pressure and average past exposure U-Hg level was found. The mean P-Se in miners (71.4 microg/L) was significantly lower (p < 0.05) than in the controls (77.3 microg/L), while the mean U-Se tended to be higher (p < 0.05) in miners (16.5 microg/g creatinine) than in the controls (14.0 microg/g creatinine). Among antioxidative enzyme activities, only CAT in erythrocytes was significantly higher (p < 0.01) in miners (3.14 MU/g Hb) than in the controls (2.65 MU/g Hb). The mean concentration of B-MEL in miners (44.3 ng/L) was significantly higher (p < 0.01) than in the controls (14.9 ng/L). The mean value of U-MEL sulphate (31.8 microg/L) in miners was significantly lower (p < 0.01) than in the control group (46.9 microg/L). Among the observed lipid peroxidative products, the mean concentration of U-MDA was statistically higher (p < 0.01) in miners (0.21 micromol/mmol creatinine) than in the controls (0.17 micromol/mmol creatinine). In the group of miners with high mercury accumulation and the presence of some nonspecific symptoms and signs of micromercurialism, the results of our study partly support the assumption that long-term occupational exposure to Hg0 enhances the formation of free radicals even several years after termination of occupational exposure. Therefore, long-term occupational exposure to Hg0 could be one of the risk factors for increased lipid peroxidation and increased mortality due to ischaemic heart disease (ICH) found among the mercury miners of the Idrija Mine.
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Sener G, Sehirli AO, Ayanoglu-Dülger G. Melatonin Protects Against Mercury(II)-Induced Oxidative Tissue Damage in Rats. ACTA ACUST UNITED AC 2003; 93:290-6. [PMID: 14675463 DOI: 10.1111/j.1600-0773.2003.pto930607.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mercury exerts a variety of toxic effects in the body. Lipid peroxidation, DNA damage and depletion of reduced glutathione by Hg(II) suggest an oxidative stress-like mechanism for Hg(II) toxicity. Melatonin, the main secretory product of the pineal gland, was recently found to be a potent free radical scavenger and antioxidant. N-Acetylcysteine, a precursor of reduced glutathione and an antioxidant, is used in the therapy of acute heavy metal poisoning. In this study the protective effects of melatonin in comparison to that of N-acetylcysteine against Hg-induced oxidative damage in the kidney, liver, lung and brain tissues were investigated. Wistar albino rats of either sex (200-250 g) were divided into six groups, each consisting of 8 animals. Rats were intraperitoneally injected with 1) 0.9% NaCl, control (C) group; 2) a single dose of 5 mg/kg mercuric chloride (HgCl2), Hg group; 3) melatonin in a dose of 10 mg/kg, 1 hr after HgCl2 injection, Hg-melatonin group; 4) melatonin in a dose of 10 mg/kg one day before and 1 hr after HgCl2 injection, melatonin-Hg-melatonin group; 5) N-acetylcysteine in a dose of 150 mg/kg, 1 hr after HgCl2 injection, Hg-N-acetylcysteine group, and 6) N-acetylcysteine in a dose of 150 mg/kg one day before and 1 hr after HgCl2 injection, N-acetylcysteine-Hg-N-acetylcysteine group. Animals were killed by decapitation 24 hr after the injection of HgCl2. Tissue samples were taken for determination of malondialdehyde, an end-product of lipid peroxidation; glutathione (GSH), a key antioxidant, and myeloperoxidase activity, an index of neutrophil infiltration. The results revealed that HgCl2 induced oxidative tissue damage, as evidenced by increases in malondialdehyde levels. Myeloperoxidase activity was also increased, and GSH levels were decreased in the liver, kidney and the lungs. All of these effects were reversed by melatonin or N-acetylcysteine treatment. Since melatonin or N-acetylcysteine administration reversed these responses, it seems likely that melatonin or N-acetylcysteine can protect all these tissues against HgCl2-induced oxidative damage.
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Affiliation(s)
- Göksel Sener
- Marmara University, School of Pharmacy, Department of Pharmacology, Istanbul, Turkey
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Shafer LL, McNulty JA, Young MR. Assessment of melatonin's ability to regulate cytokine production by macrophage and microglia cell types. J Neuroimmunol 2001; 120:84-93. [PMID: 11694323 DOI: 10.1016/s0165-5728(01)00419-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Evidence in support of melatonin's role as an immunomodulator is incomplete and, in some cases, contradictory. The present studies determined whether melatonin modulates the activity of stimulated macrophages. In vitro lipopolysaccharide (LPS, 10-1000 ng/ml) treatment of alveolar, splenic and peritoneal macrophages isolated from mice and/or rats resulted in a dose-dependent increase in interleukin-1beta (IL-1beta) and tumor necrosis factor (TNF-alpha) secretion. Treatment with melatonin (10(-10)-10(-6) M) prior to the addition of LPS, had no effect on IL-1beta or TNF-alpha release. Additionally, melatonin had no effect on stimulated BV2 microglial cell line cytokine secretion. To determine whether melatonin had an indirect effect on macrophage cytokine release via T cells, melatonin was added to unfractionated mouse spleen cells. Again, melatonin showed no priming effect on LPS-stimulated spleen cells. These results suggest that melatonin has no direct or indirect effect on mouse and rat macrophages. In vivo studies, where melatonin was continuously available in the drinking water, showed that melatonin did not have a priming effect on LPS-stimulated mouse peritoneal macrophages. These findings suggest that melatonin is not an important modulator of macrophage and microglia function.
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Affiliation(s)
- L L Shafer
- Department of Cell Biology, Neurobiology and Anatomy, Loyola University of Chicago Medical Center, 2160 S. First Avenue, Maywood, IL 60153, USA
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