Effects of inorganic selenium administration in methylmercury-induced neurotoxicity in mouse cerebral cortex.
Selenium can counteract methylmercury (MeHg) neurotoxicity. However, data about the neuroprotective effects of sodium selenite (Na(2)SeO(3)) on the activity of mitochondrial complexes and creatine kinase (mtCK) are scarce. Therefore, this study investigated the effects of the chronic exposure to Na(2)SeO(3) on brain energy metabolism and oxidative stress parameters in MeHg-poisoned mice. Adult male mice were orally treated with MeHg (40 mg L(-1) in drinking water, ad libitum) during 21 days and simultaneously administrated with daily subcutaneous injections of Na(2)SeO(3) (5 μmol kg(-1)), a potential neuroprotectant. Mitochondrial complexes I to IV and mtCK activities were measured in cerebral cortex mitochondria. The cerebro-cortical tissue was also used to evaluate the antioxidant enzymes glutathione peroxidase (GPx) and glutathione reductase (GR) activities, as well as lipid peroxidation. Metal deposition was followed autometalographically (AMG). Na(2)SeO(3) partially prevented MeHg-induced inhibition of complexes II-III, IV and mtCK activities; however, it was unable to prevent MeHg-induced complex I and II inhibition. MeHg increased lipid peroxidation, GR activity and decreased GPx activity in the cerebral cortex; however, Na(2)SeO(3) did not modify such events. Furthermore, Na(2)SeO(3)per se inhibited complexes I, II-III and IV and mtCK activities and increased GPx and GR activities and lipid peroxidation. These data show that inorganic selenium was ineffective in preventing most of the MeHg-induced brain biochemical alterations. However, the most prominent finding was the selenium-induced reduction of cells labelled for metal deposition. Although, the literature supports the beneficial effects of selenium against mercury toxicity, the toxic effects elicited by Na(2)SeO(3), alone or in combination with mercury, should be considered when this compound is proposed as a potential protective therapy for MeHg poisoning.
Glaser
Viviane
V
Laboratório de Bioenergética e Estresse Oxidativo, Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
Nazari
Evelise Maria
EM
Müller
Yara Maria Rauh
YM
Feksa
Luciane
L
Wannmacher
Clóvis Milton Duval
CM
Rocha
João Batista Teixeira
JB
de Bem
Andreza Fabro
AF
Farina
Marcelo
M
Latini
Alexandra
A
D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects; D008297:Male; D008767:Methylmercury Compounds / Q000633:toxicity*; D051379:Mice; D020258:Neurotoxicity Syndromes / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D018038:Sodium Selenite / Q000008:administration & dosage* / Q000494:pharmacology
D008767:Methylmercury Compounds; D018038:Sodium Selenite