[The role of G-proteins and second messenger systems in the plasticity of the avoidance reflex in the snail].

An increase in the activity of G-proteins and protein kinase A was shown in the brain of Helix at the early stages of learning. The protein kinase C activity did not differ from the baseline in 20-40 min after training. There was no difference between the brain G-protein activities in the young (unable to learn) and adult snails. A conclusion is drawn that the system of cAMP-dependent phosphorylation and cAMP-dependent activation of the early genes actively participate in learning of Helix. The participation of additional systems of intracellular regulation in learning is discussed.