[The neurochemical correlates of plasticity].

Water-soluble proteins in the CNS of Helix pomatia were studied by the method of disk electrophoresis in polyacrylamide gel. The protein Rf 0.58 proved to be absent in young snails, while in adults its amount varied from 3% (naive snails) to 6-10% (trained animals) of the proteins separated by the method used. Incubation of the adults' ganglia in saline containing serotonin or NaF led to a significant elevation of the protein Rf 0.58 quantity. Neither serotonin nor NaF induced the protein Rf 0.58 in the young snails. We suggest the protein Rf 0.58 to be related to G-proteins. Late maturation of G-proteins might be one of the reasons of low behavioural plasticity in the young snails. Influence of acetylcholine on the protein synthesis in the identified "pool D" neurons was studied too. Protein fractions were identified, in which the intensity of labelling increased up to 400-500% of the control level. Acetylcholine is supposed to modulate the protein synthetizing system in these neurons.