LACTATE-DEHYDROGENASE AND GLUTAMATE-DEHYDROGENASE ACTIVITIES IN THE CIRCUMVENTRICULAR ORGANS OF RAT-BRAIN FOLLOWING NEONATAL MONOSODIUM GLUTAMATE

Glutamate (glu) an excitatory neurotransmitter amino acid, is present in high concentrations in the mammalian central nervous system and is the most abundant amino acid in our daily diet. In the present study t he activities of lactate dehydrogenase (LDH) and glutamate dehydrogena se (GDH) were evaluated in the circumventricular organs (CVO) of the b rain in 25-day-old rats following MSG administration at a dose of 4 mg /g b.wt during the first ten days of life. The results show the LDH ac tivity increased to 265% of that in the control (p<0.001), whereas GDH activity was significantly decreased (p<0.05), The great elevation in LDH, a cytoplasmic marker enzyme, is apparently due to cytoskeletal c hanges brought about as a consequence of glu toxicity, whereas lowered GDH activity indicates altered glu homostasis in the blood-brain-barr ier deficient areas following neonatal exposure of glu.