RESUMEN
On brain slices from healthy guinea pigs and animals with a model of chronic temporal lobe epilepsy, a comparative study of GABAergic modulation of oscillatory activity of neurons in the medial septal area was carried out. Under the action of GABA, burst activity persisted only in pacemakers in both groups of preparations. In epilepsy, the effectiveness of GABA action on the rhythmic neurons sharply increased. In the control group, GABA significantly reduced bursts frequency in cells preserving their oscillatory activity, whereas in slices from the epileptic brain burst frequency increased under the action of GABA. Blockade of GABAergic receptors led to a disruption of tonic GABAergic intraseptal influences and to a significant decrease in the effectiveness of blockers in epilepsy. The study was the first to demonstrate a dysfunction of the septal GABAergic system in temporal lobe epilepsy, which is a possible cause of a sharp change in the oscillatory properties of septal neurons. These findings contribute to elucidation of the mechanisms of temporal lobe epilepsy.
Asunto(s)
Relojes Biológicos/fisiología , Epilepsia del Lóbulo Temporal/fisiopatología , Tabique del Cerebro/fisiología , Ácido gamma-Aminobutírico/fisiología , Animales , Relojes Biológicos/efectos de los fármacos , Enfermedad Crónica , Modelos Animales de Enfermedad , Antagonistas del GABA/farmacología , Cobayas , Neuronas/efectos de los fármacos , Neuronas/fisiología , Tabique del Cerebro/efectos de los fármacosRESUMEN
Comparative studies of the activity of extracellularly recorded neurons in living slices of the medial septal area of healthy guinea pigs and animals with a model of chronic temporal epilepsy demonstrated differences between them in terms of the frequency and pattern of cell discharges. The brains of animals with experimental epilepsy showed a doubling of the total level of activity as compared with controls, due to increases in the discharge frequencies of irregular and regular non-volleying neurons. There was a sharp (three-fold) increase in the number of cells with rhythmic discharge volleys, along with changes in the parameters of volley activity - both in neurons with the endogenous (pacemaker) pattern and in cells with secondary involvement in rhythmic activity. The possible mechanisms for these changes are discussed. These data widen our understanding of the processes forming pathological synchronization in epilepsy and may assist in the creation of new approaches to the treatment of this disease.
Asunto(s)
Neuronas/fisiología , Periodicidad , Tabique del Cerebro/fisiopatología , Potenciales de Acción , Animales , Modelos Animales de Enfermedad , Epilepsia/inducido químicamente , Epilepsia/fisiopatología , Agonistas de Aminoácidos Excitadores/efectos adversos , Cobayas , Ácido Kaínico/efectos adversos , Factores de TiempoRESUMEN
Comparative investigation of activity of medial septal neurons, which was performed by extracellular recordings in the brain slices of health guinea pigs and in such ones of animals with the model of chronic temporal lobe epilepsy, revealed the distinctions between them, concerning a neuronal frequency and pattern of discharges. In the epileptic brain, twofold increase of general level of activity was observed comparative to control one, owing to augmentation of frequency of discharges in non-regular and regular non-bursting neurons. Sharp increase (three times as much) of number of cells with rhythmic burst discharges and changing of parameters of burst activity were discovered, the letter both in the neurons with endogenous (pacemaker) pattern and in the cells secondary involved in the rhythmic activity. Possible mechanisms of these alterations are discussed. The present data advance the understanding of the processes of a pathological synchronization and may promote creation of new approaches to treatment this disease.