Influence of mRNA and protein synthesis inhibitors on the long-term memory acquisition of classically conditioned earthworms

Neurobiol Learn Mem. 2005 Mar;83(2):151-7. doi: 10.1016/j.nlm.2004.11.003.


We investigated the process of memory consolidation following classical conditioning of earthworms. Earthworms were conditioned in paired trials by a weak vibration as a conditioned stimulus (CS), and by light as an unconditioned stimulus (US). The occurrence of a shrinking response upon exposure to the CS increased steadily with the number of paired training trials. When the training procedure was changed by increasing the intertrial interval (ITI), it was found that only those worms trained with a 68 s ITI exhibited long-term memory retention for at least 24 h. The influence of mRNA synthesis inhibition by actinomycin-D or of protein synthesis by anisomycin on memory consolidation was also examined. Induction of the long-term memory was blocked when either of these two compounds was injected into the body cavity of the worm within 25 min of conditioning with the 68 s ITI. These results demonstrate that the long-term memory is dependent upon protein synthesis in response to the upregulation of new transcription messengers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anisomycin / pharmacology*
  • Association Learning / drug effects
  • Association Learning / physiology
  • Avoidance Learning / drug effects
  • Avoidance Learning / physiology
  • Dactinomycin / pharmacology*
  • Injections
  • Mental Recall / drug effects
  • Mental Recall / physiology
  • Nerve Tissue Proteins / antagonists & inhibitors*
  • Nerve Tissue Proteins / physiology*
  • Nervous System Physiological Phenomena / drug effects
  • Oligochaeta / drug effects
  • Oligochaeta / physiology*
  • Protein Synthesis Inhibitors / pharmacology*
  • RNA, Messenger / antagonists & inhibitors*
  • RNA, Messenger / physiology*
  • Retention, Psychology / drug effects*
  • Retention, Psychology / physiology*
  • Time Perception / drug effects
  • Time Perception / physiology
  • Vibration


  • Nerve Tissue Proteins
  • Protein Synthesis Inhibitors
  • RNA, Messenger
  • Dactinomycin
  • Anisomycin