title: Evidence that oxidative stress is involved in the inhibitory effect of proline on Na(+),K(+)-ATPase activity in synaptic plasma membrane of rat hippocampus.
abstract: In the present study, we investigated the effect of Vitamins E and C on the inhibition of Na(+),K(+)-ATPase activity provoked by proline (Pro) administration in rat hippocampus. Five-day-old rats were pretreated for 1 week with daily i.p. administration of saline (control) or Vitamin E (40 mg/kg) and Vitamin C (100 mg/kg). Twelve hours after the last injection, animals received one single injection of Pro (12.8 micromol/g of body weight) or saline and were killed 1h later. Results showed that Na(+),K(+)-ATPase activity was decreased in the Pro-treated rats and that the pretreatment with Vitamins E and C prevented this effect. In another set of experiments, we investigated the in vitro effect of 1.0 mM Pro on Na(+),K(+)-ATPase activity from synaptic membranes of hippocampus of rats. Pro significantly inhibited (30%) Na(+),K(+)-ATPase activity. We also evaluated the effect of preincubating glutathione, trolox and N(pi)-nitro-L-arginine methyl ester (L-NAME) alone or combined with Pro on Na(+),K(+)-ATPase activity. Tested drugs did not alter Na(+),K(+)-ATPase activity, but glutathione prevented the inhibitory effect of Pro on this enzyme activity. These results suggest that the in vivo and in vitro inhibitory effect of Pro on Na(+),K(+)-ATPase activity is probably mediated by free radicals that may be involved in the neurological dysfunction found in hyperprolinemic patients.
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo CEP 90035-003, Porto Alegre, RS, Brazil.
authors.forename: Renata
authors.initials: R
authors.lastname: Franzon
authors.forename: Marcelo L
authors.initials: ML
authors.lastname: Lamers
authors.forename: Francieli M
authors.initials: FM
authors.lastname: Stefanello
authors.forename: Clóvis 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: D000592:Amino Acid Metabolism, Inborn Errors / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D011392:Proline / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013570:Synaptic Membranes / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D014810:Vitamin E / Q000494:pharmacology*
chemical_list: D014810:Vitamin E; D011392:Proline; D000254:Sodium-Potassium-Exchanging ATPase; D001205:Ascorbic Acid