[Comparative analysis of MAP/ERK-kinase activation in the CNS of animals with different capability for learning]

With the Western-blot analysis, we studied the activation of MAP/ERK protein kinases (regulating genes expression by the phosphorylation of transcription factors (TF) CREB and ELK-1) in native Helix pomatia and in animals with disturbed abilities to form long-term conditioned avoidance reflexes. Different stages of this reflex formation were shown to be characterized by different levels of MAP/ERK kinases activation, the latter being different in CNS's regions (visceral complex of ganglia, cerebral and pedal ganglia) playing different roles in the reflex formation. The dynamics of activation was wave-shaped with peaks at 10 min and 4 h. The treatment of snails with the neurotoxin 5,7-DHT (causing disfunction of serotoninergic terminals and reducing capability for this reflex formation) resulted in significant decrease of MAP/ERK kinase cascade activation at earlier stages of learning, which suggest an important role of serotoninergic system in this cascade activation. The activation of MAP/ERK kinase cascade in 4 hours after training was observed in native as well as in DHT-treated animals, which seems to suggest, switching on nonspecific adaptive processes in response to sensitizing unconditioned stimulus. Thus, MAP/ERK kinase intracellular regulatory cascade playing an important role in neuron survival, processes regeneration and synaptic sprouting plays an important role in the formation of serotonin-dependent food aversion reflex in Helix pomatia.