CORTICAL ABLATION AND DRUG-INDUCED CHANGES IN STRIATAL ASCORBIC-ACID OXIDATION AND BEHAVIOR IN THE RAT

Rats whose frontoparietal cortex had been bilaterally ablated were all owed 21 days for recovery and then treated with apomorphine (APO), 1 m g/kg SC or scopolamine (SCOP), 0.6 mg/kg SC. Soon after a behavioral t est, dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), ascorbic a cid (AA), and dehydroascorbic acid (DHAA) levels were determined by HP LC/EC in striatal synaptosomes (left side) and whole striatum (right s ide). SCOP behavioural effects were attenuated by cortical ablation, w hile those of APO were affected to a lesser extent. In the striatum of unoperated and sham-operated rats DHAA contents and DHAA/AA ratio res ulted increased after drugs administration. No change in AA oxidation was observed in the striatum of ablated rats. In the synaptosomes of u noperated and sham-operated rats both drugs led to a decrease in DHAA contents and DHAA/AA ratio. In unoperated and sham-operated rats APO a nd SCOP caused a decrease of the DOPAC/DA ratio in the whole striatum and striatal synaptosmes. In ablated rats APO caused a decrease of DOP AC/DA ratio in the whole striatum and synaptosomes, while SCOP effects on DA turnover resulted attenuated in the whole striatum and abolishe d in synaptosomes. We conclude that drug-induced AA oxidation is likel y to occur in the extracellular space and requires intact corticostria tal glutamatergic pathways. The latter may play an enabling role in SC OP behavioral effects.