title: Methionine alters Na+,K+-ATPase activity, lipid peroxidation and nonenzymatic antioxidant defenses in rat hippocampus.
abstract: In the present study we investigated the effect of methionine exposure of hippocampus homogenates on Na+,K+-ATPase activity from synaptic plasma membrane of rats. Results showed that methionine significantly decreased this enzyme activity. We also evaluated the effect of incubating glutathione (GSH) and trolox (alpha-tocopherol) alone or combined with methionine on Na+,K+-ATPase activity. The tested antioxidants per se did not alter the enzymatic activity, but prevented the inhibitory action of methionine on Na+,K+-ATPase activity, indicating that Met inhibitory effect was probably mediated by free radical formation. Besides, we tested the in vitro effect of methionine on some parameters of oxidative stress, namely chemiluminescence, thiobarbituric acid reactive substances (TBARS), total radical-trapping antioxidant potential (TRAP), as well as on the antioxidant enzyme activities catalase, glutathione peroxidase and superoxide dismutase in rat hippocampus. We observed that methionine significantly increased chemiluminescence and TBARS, decreased TRAP, but did not change the activity of the antioxidant enzymes. These findings suggest that reduction of Na+,K+-ATPase activity and induction of oxidative stress may be involved in the brain damage observed in human hypermethioninemia.
authors.affiliation: Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil.
authors.forename: Francieli M
authors.initials: FM
authors.lastname: Stefanello
authors.forename: Fábria
authors.initials: F
authors.lastname: Chiarani
authors.forename: Andréa G
authors.initials: AG
authors.lastname: Kurek
authors.forename: Clovis M D
authors.initials: CM
authors.lastname: Wannmacher
authors.forename: Moacir
authors.initials: M
authors.lastname: Wajner
authors.forename: Angela T S
authors.initials: AT
authors.lastname: Wyse
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects*; D008163:Luminescent Measurements; D008715:Methionine / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D013570:Synaptic Membranes / Q000201:enzymology / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances
chemical_list: D000975:Antioxidants; D009419:Nerve Tissue Proteins; D017392:Thiobarbituric Acid Reactive Substances; D008715:Methionine; D002374:Catalase; D013482:Superoxide Dismutase; D000254:Sodium-Potassium-Exchanging ATPase; D005978:Glutathione