Inhibition of the thioredoxin system in the brain and liver of zebra-seabreams exposed to waterborne methylmercury

Journal Article · Tue Mar 01 00:00:00 EST 2011 · Toxicology and Applied Pharmacology

DOI:https://doi.org/10.1016/j.taap.2010.12.005· OSTI ID:21535244

Branco, Vasco ^[1]; Canario, Joao ^[2]; Holmgren, Arne ^[3]; Carvalho, Cristina ^[1]

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1. Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon. Av. Prof. Gama Pinto, 1649-003 Lisbon (Portugal)
2. Marine Environment and Biodiversity Unit, National Institute for Biological Resources (IPIMAR/INRB), Av. Brasilia 1440-006 Lisbon (Portugal)
3. Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm (Sweden)

Mercury compounds were recently found to interact in vitro with the thioredoxin system, inhibiting both Thioredoxin (Trx) and Thioredoxin reductase (TrxR). In order to evaluate if Trx and TrxR are affected in vivo by methylmercury (MeHg), we exposed juvenile zebra-seabreams to different concentrations of this toxicant in water for 28 days followed by a 14-day depuration period. Methylmercury accumulated to a larger extent in the kidney and liver of fishes, but decreased significantly during the depuration. During the exposure, MeHg percentage in the liver reached levels above 90% of total mercury (HgT) decreasing to 60% of HgT by the end of the depuration period. In the kidney, MeHg accounted for 50-70% of HgT. In the brain and muscle, mercury accumulated throughout the exposure with all mercury being MeHg. The total mercury kept increasing in these organs during the depuration period. However, in the brain, this increase in HgT was accompanied by a decrease in the MeHg percentage ({approx} 10%). In the liver, both Trx and TrxR activities were significantly reduced (TrxR - 40%; Trx - 70%) by the end of the exposure, but recovered to control levels (100%) during the depuration. In the brain, both enzymes where inhibited during the depuration period (TrxR - 75%; Trx - 70%) when some production of inorganic mercury was detected. Activity of glutathione reductase showed increased levels when TrxR activity was low, suggesting complementarity between both systems. These results indicate that in vivo the thioredoxin system is a toxicological target for MeHg with TrxR being particularly affected.

• OSTI ID: 21535244
• Journal Information: Toxicology and Applied Pharmacology, Vol. 251, Issue 2; Other Information: DOI: 10.1016/j.taap.2010.12.005; PII: S0041-008X(10)00454-0; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
BRAIN
CONTROL
FISHES
GLUTATHIONE
IN VITRO
IN VIVO
INHIBITION
JUVENILES
KIDNEYS
LIVER
MERCURY
MERCURY COMPOUNDS
METHYLMERCURY
MUSCLES
SUPEROXIDE DISMUTASE
THIOLS
ANIMALS
AQUATIC ORGANISMS
BODY
CENTRAL NERVOUS SYSTEM
DIGESTIVE SYSTEM
DRUGS
ELEMENTS
ENZYMES
GLANDS
METALS
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANIC MERCURY COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
OXIDOREDUCTASES
PEPTIDES
POLYPEPTIDES
PROTEINS
RADIOPROTECTIVE SUBSTANCES
RESPONSE MODIFYING FACTORS
VERTEBRATES