Contribution of Epigenetic Mechanisms to the Formation, Maintenance, and Reconsolidation of a Long-Term Food-Related Aversive Memory in Terrestrial Snails

The study reported here analyzed the role of epigenetic mechanisms (histone acetylation, DNA methylation, and histone serotonylation) in the formation, storage, and reconsolidation of long-term food-related aversive memory in snails. The first part of the work addressed the effect of systemic administration of the histone deacetylase inhibitor sodium butyrate in a model of conditioned reflex food aversion in snails. Administration of sodium butyrate to animals with poor memory was found to result in enhancement of memory. Administration of the DNA methyltransferase blocker RG108 showed that impaired DNA methylation degraded long-term food-related aversive memory in snails. However, memory reactivation neutralized the effect of inhibition of DNA methyltransferase activity. The final section of the work tested the hypothesis that transglutaminase-mediated serotonylation is involved in the processes of reconsolidation of an aversive food-related memory in snails. Behavioral analysis showed that administration of the transglutaminase blocker monodansylcadaverine (producing blockade of serotonylation) after a reminder disrupted the reconsolidation process and led to memory suppression/erasure.