[Different mechanisms of long-term synaptic facilitation during associative learning and sensitization]

The translation and transcription processes involved in mechanisms of synaptic plasticity during the development of conditional taste aversion were studied in command neurons LP11 and PP11 of defensive behavior in snail Helix lucorum. In control snails it was found that the combined presentation of gustatory (carrot juice) and supporting (concentrated solution of quinine) stimulus led to a change in neuron's responses to sensory stimulus, which are typical as to conditioning and also to the corresponding sensitization. 1 h after the start of training it was occurred facilitation of the responses to sensory chemical stimulus (weak solution of quinine) whereas 1.5 hour--reactions to the conditioned food stimulus. Application of the protein synthesis inhibitor cycloheximide during conditioning led to the suppression of response facilitation to both stimulus--weak solution of quinine and the conditioned food stimulus. However, application of the RNA synthesis inhibitor actinomycin D to the neurons caused selective suppression of synaptic facilitation in responses to sensory stimulation with a weak solution of quinine, but it had no effect on synaptic facilitation in the responses to the conditioned stimulus. It has been suggested that the development of conditioned taste aversion in snails causes a long-term synaptic facilitation in nerve cells LP11 and PP11 typical to the process of conditioning and sensitization, for the induction of which the variety of molecular genetic mechanisms are necessary.