Central activity of 2-amino-3-phosphonopropionic acid (AP3) and its N-methyl analog

The influence of 2-amino-3-phosphonopropionic acid (AP3) an antagonist of metabotropic glutamate receptors and its N-methyl analog (N-methyl AP3) on locomotor activity in the "open field" test, apomorphine stereotypy and haloperidol catalepsy were tested. Both compounds had not any influence on spontaneous crossings of squares, number of rearings and bar approaches in the "open field" test. AP3 and its N-methyl analog significantly enhanced apomorphine stereotypy at the intracerebroventricular (icv) doses of 100 and 200 micrograms per rat respectively. Although, both compounds significantly diminished haloperidol catalepsy at the icv doses of 50, 100 and 200 micrograms per rat. All observed effects of AP3 and N-methyl AP3 were dose independent. Methyl substitution at the N-position in AP3 did not change pharmacological properties of this compound i.e. its influence on behavior mainly dependent on dopaminergic systems.