Evidence that oxidative stress is involved in the inhibitory effect of proline on Na+,K+-ATPase activity in synaptic plasma membrane of rat hippocampus

• Published in: International journal of developmental neuroscience 2003-10, Vol.21 (6), p.303-307
• Main Authors: Franzon, Renata, Lamers, Marcelo L., Stefanello, Francieli M., Wannmacher, Clóvis M.D., Wajner, Moacir, Wyse, Angela T.S.
• Format: Article
• Language: English
• Subjects: Amino Acid Metabolism, Inborn Errors - metabolism; Animals; Ascorbic Acid - pharmacology; Enzyme Activation - drug effects; Hippocampus; Hippocampus - drug effects; Hippocampus - enzymology; Hippocampus - metabolism; Hyperprolinemia; Na+,K+-ATPase; Oxidative Stress - drug effects; Oxidative Stress - physiology; Proline; Proline - pharmacology; Rats; Rats, Wistar; Reference Values; Sodium-Potassium-Exchanging ATPase - antagonists & inhibitors; Sodium-Potassium-Exchanging ATPase - metabolism; Synaptic Membranes - drug effects; Synaptic Membranes - enzymology; Synaptic Membranes - metabolism; Vitamin E - pharmacology; Vitamins E and C
• ISSN: 0736-5748; 1873-474X
• DOI: 10.1016/S0736-5748(03)00076-5

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 (40mg/kg) and Vitamin C (100mg/kg). Twelve hours after the last injection, animals received one single injection of Pro (12.8μmol/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 1.0mM 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 Nϖ-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.