Central activity of 2-amino-4-phosphonobutyric acid (AP4).

The influence of intracerebroventricular (icv) injections of 2-amino-4-phosphonobutyric acid (AP4) on the activity of central nervous system was examined in rats. The compound (100 and 200 micrograms icv) significantly enhanced apomorphine stereotypy, in doses of 50, 75, and 100 micrograms decreased haloperidol-induced catalepsy and did not change motility of rats estimated in the "open field" test. AP4 significantly improved learning and memory processes in passive and learning in active avoidance situation. The highest significant effect was observed after icv dose of 100 micrograms per rat, when acquisition, consolidation and recall of information was evaluated in the passive avoidance behavior. AP4 significantly improved only acquisition of information in active avoidance situation at the icv dose of 50 micrograms per rat. The mechanism of the positive effect of AP4 on learning and memory is at present unclear, and its explanation needs future investigations.