CHRONIC NEONATAL BLOCKADE OF NMDA RECEPTOR DOES NOT AFFECT DEVELOPMENTAL POLYAMINE METABOLISM BUT RESULTS IN ALTERED RESPONSE TO THE EXCITOTOXIC INDUCTION OF ORNITHINE DECARBOXYLASE

Neonatal rats were subjected to chronic blockade of the N-methyl-D-asp artate (NMDA) receptor through daily systemic administration of increa sing doses of the competitive antagonist CGP 39551 from postnatal days 1-22. Treatment did not result in any significant alteration of the l evels of putrescine, spermidine and spermine or in the constitutively expressed activity of the key enzyme for polyamine biosynthesis, ornit hine decarboxylase (ODC), as evaluated al 10 and 20 days of age. Howev er, in 30-day-old rats significant differences were observed in the pr ocess of excitotoxic ODC induction in the olfactory cortex and the hip pocampus of chronically-treated rats: the increase of ODC activity cau sed by systemic administration of kainic acid look place more rapidly but it was shorter and apparently reached a smaller peak in treated an imals as compared to controls. This result, in conjunction with previo us data on neurochemistry and locomotor activity of similarly treated rats, strengthens the suggestion that functional alterations of some b rain circuits may be the consequence of the blockade of NMDA receptor during the critical neonatal period of brain maturation.