Effects of 5-HT and insulin on learning and memory formation in food-deprived snails

Hitoshi Aonuma, Yuki Totani, Mugiho Kaneda, Ryota Nakamura, Takayuki Watanabe, Dai Hatakeyama, Varvara E. Dyakonova, Ken Lukowiak, Etsuro Ito*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


The pond snail Lymnaea stagnalis learns conditioned taste aversion (CTA) and consolidates it into long-term memory (LTM). How well they learn and form memory depends on the degree of food deprivation. Serotonin (5-HT) plays an important role in mediating feeding, and insulin enhances the memory consolidation process following CTA training. However, the relationship between these two signaling pathways has not been addressed. We measured the 5-HT content in the central nervous system (CNS) of snails subjected to different durations of food deprivation. One-day food-deprived snails, which exhibit the best learning and memory, had the lowest 5-HT content in the CNS, whereas 5-day food-deprived snails, which do not learn, had a high 5-HT content. Immersing 1-day food-deprived snails in 5-HT impaired learning and memory by causing an increase in 5-HT content, and that the injection of insulin into these snails reversed this impairment. We conclude that insulin rescues the CTA deficit and this may be due to a decrease in the 5-HT content in the CNS of Lymnaea.

Original languageEnglish
Pages (from-to)20-29
Number of pages10
JournalNeurobiology of Learning and Memory
Publication statusPublished - 2018 Feb


  • Conditioned taste aversion
  • Feeding
  • Food-deprivation
  • Insulin
  • Lymnaea
  • Serotonin

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Cognitive Neuroscience
  • Behavioral Neuroscience


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