[A morphofunctional analysis of the participation of the cerebral cortex in the habituation of Krushinskiĭ-Molodkina strain rats to an epileptogenic stimulus]

Abstract

Systematic action of epileptogenic stimulus (sound) leads to gradual lowering of the level of convulsive readiness (LCR) in rats of KM (Krushinski'i-Molodkina) line to the formation of the habituation, to blocking of convulsive seizures. It is shown that at single action of sound, functional switching-off of the cerebral cortex causes LCR lowering but does not prevent the development of the epileptiform seizure. Alongside with it, in conditions of repeated sound action, functional decortication considerably retards LCR lowering. After cessation of the cortical depression, during which the rats were given systematic sound exposition, sharp LCR lowering takes place. If the habituation has been already formed, then the subsequent switching-off of the cortex does not lead to LCR growth. Ultrastructural characteristics of asymmetric axo-dendritic and axo-spine synapses in the auditory cerebral cortex of KM line rats in the moment of convulsive seizure testifies to their active functioning, while against the background of short-term habituation to epileptogenic stimulus signs of lowering of the efficiency of synaptic transmission are revealed in these synapses. The obtained results allow to suggest that in the rats of KM line the neocortex takes part in antiepileptic defensive reactions, in LCR regulation in connection with formation of the habituation to systematic action of epileptogenic stimulus.