PKC and Calpain RNA expression level changes with long-term memory in Aplysia
Protein synthesis has been shown to be crucial in learning and memory. Particularly, the activity of protein kinase C (PKC) is necessary for long-term memory. Previous studies have shown that serotonin pathway had a profound effect on PKC, and it facilitates long-term potentiation. To study the fundamental molecular processes involved, Aplysia was used to evaluate the changes in RNA expression levels. Ganglia-treated samples as well as behaviorally trained samples were used to analyze any differences after training and the use of drugs, chelerythrine, a selective PKC inhibitor, and Trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor. Application of these drugs may reveal different regulatory mechanisms that govern transcription level changes, ultimately leading to protein synthesis. Although the results did not show statistical significance, the pattern of slightly increased RNA level of PKC and calpain after serotonin or behavior training show there is a possible correlation between long-term memory and nuclear regulation of protein synthesis. In addition, because TSA was able to reverse the effects of chelerythrine, there is an indication that an epigenetic regulation may be involved in memory. However, molecular analysis demonstrated inconclusive data, suggesting further examinations of the epigenetic changes exhibiting a brief cellular response.