[Selective disturbance of associative memory reactivation by serotonin or NMDA glutamate receptor antagonists in snail].

Effects of serotonin or glutamate receptors antagonists on reactivation of food aversion conditioning were studied in snail Helix lucorum. Metiotepin (nonselective serotonin receptor antagonist, 0.1 mg/snail) or MK-801 (NMDA glutamate receptor antagonist, 0.005 mg/snail) were injected 24 hours after 3 days of food aversion conditioning, then reminding stimulus (banana, "conditioned" food) was presented and food aversion conditioning was tested. Long-term impairing (more then 2 weeks) of food aversion conditioning was found 3 hours after concurrent reminding and inhibitors injection. Injection of receptor antagonists without reminding stimulus did not influence on food aversion conditioning retrieval. Besides, in snails with amnesia after metiotepin/reminder, facilitation of repeated elaboration aversion conditioning on banana is revealed. The repeated training of snails with amnesia caused by MK-801/reminder did not result in food aversion conditioning. It is was suggested that 5-HT5,6,7 serotonin receptors are involved in mechanisms of memory "trace" extraction of food aversion conditioning, whereas NMDA glutamate receptor - in processes of its storage in snail.