Suckling rat brain regional distribution of Na+,K+-atpase activity in the in vitro galactosaemia: the effect of L-cysteine and glutathione.
Inhibition of Na+,K+-ATPase activity causes edema and cell death in central nervous system. We determined the in vitro effects of galactose-l-phosphate (Gal-1-P), galactitol (Galtol) and galactose (Gal) (mix A = classical galactosaemia) or Galtol and Gal (mix B = galactokinase deficiency galactosaemia), on Na+,K+-ATPase activity in suckling rat brain frontal cortex, hippocampus or hypothalamus homogenates. Gal-1-P or Galtol alone at different concentrations, significantly inhibited Na+,K+-ATPase whereas Gal activated the enzyme in all investigated brain regions. Both mix A and mix B inactivated the enzyme by 20-30% (p < 0.001) in all studied areas. L-Cysteine (Cys) and glutathione (GSH) supplementation in mix B not only reversed the enzyme inhibition but also resulted in an activation of 50-60%, (p < 0.001) in all brain areas. Their presence in mix A also activated the inhibited Na+,K+-ATPase in hippocampus and hypothalamus to a lower degree, whereas Cys reversed the frontal cortex enzyme activity to control value only. These findings indicate that oxidation of the enzyme critical groups may be involved in galactosaemia, producing inhibitory effect. This phenomenon is reversed by antioxidants Cys and GSH, implying that free radicals may be implicated in the observed enzyme inactivation.
Marinou
Kyriakoula
K
Department of Experimental Physiology, Medical School, University of Athens, P.O Box 65257, GR-15401, Athens, Greece.
Tsakiris
Stylianos
S
Tsopanakis
Christi
C
Schulpis
Kleopatra H
KH
Behrakis
Panagiotis
P
D000818:Animals; D000833:Animals, Suckling; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology; D003545:Cysteine / Q000378:metabolism* / Q000494:pharmacology; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D004376:Galactitol / Q000378:metabolism / Q000494:pharmacology; D005690:Galactose / Q000378:metabolism / Q000494:pharmacology; D005693:Galactosemias / Q000150:complications / Q000378:metabolism*; D005695:Galactosephosphates / Q000378:metabolism / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism* / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism
D000975:Antioxidants; D005609:Free Radicals; D005695:Galactosephosphates; D004376:Galactitol; C029973:galactose-1-phosphate; D000254:Sodium-Potassium-Exchanging ATPase; D005978:Glutathione; D003545:Cysteine; D005690:Galactose