RESUMO
Quantitative analysis of the main cells and interneurons in different layers and fields of Ammon's horn, the hilus, and dentate gyrus was performed two weeks and one month after kindling, i.e., specific electrical stimulation of the ventral hippocampus. At both experimental time points, cells numbers were significantly decreased at all levels of the areas studied except the marginal layer of field CA4. Thus, in this model of experimental epilepsy, the process of epileptogenesis involved both interneurons and main cells in the hippocampus. The possible reorganization of intrahippocampal circuits and their involvement in the increased excitability characteristic of epilepsy are discussed.
Assuntos
Epilepsia/patologia , Hipocampo/patologia , Excitação Neurológica/patologia , Neurônios/patologia , Animais , Morte Celular , Giro Denteado/patologia , Modelos Animais de Doenças , Estimulação Elétrica , Masculino , RatosRESUMO
Quantitative analysis was performed to evaluate the numbers of principal cells cells and interneurons in differenet layers and areas of the horn of Ammonis, hilus and dentate gyrus 2 weeks and 1 month after kindling--specific electrical stimulation of ventral hippocampus. After both experimental time intervals, a significant cell loss was found in all the layers and areas studied, with the exception of stratum oriens of CA4. Thus, in this model of experimental epilepsy, both interneurons and principal cells were found to be involved in the process of epileptogenesis. Different possibilities of reorganization of intrahippocampal circuits and their participation in increased excitability, typical to epilepsy, are discussed.
Assuntos
Epilepsia/etiologia , Epilepsia/patologia , Hipocampo/patologia , Excitação Neurológica , Neurônios/patologia , Animais , Contagem de Células , Morte Celular , Modelos Animais de Doenças , Estimulação Elétrica , Interneurônios/patologia , Masculino , RatosRESUMO
GABAergic neurons in different fields of the hippocampus and pyriform cortex were examined 2 weeks and 1 month after electric stimulation of the ventral hippocampus. The counts of GABAergic neurons in the studied structures decreased significantly. The most pronounced shifts in the pyriform cortex were found in the central compartment. Decreased number of inhibitory elements in the two major epileptogenic structures attests to appreciable restructuring in the functions of their neuronal circles.
Assuntos
Hipocampo/citologia , Neurônios/fisiologia , Condutos Olfatórios/citologia , Animais , Estimulação Elétrica , Imuno-Histoquímica , Masculino , Neurônios/metabolismo , Ratos , Fatores de Tempo , Ácido gama-Aminobutírico/metabolismoRESUMO
The paper reviews the current data on the structural peculiarities of the interneurons of hippocampal area CA 3. Special attention is paid to horizontal spiny interneurons located in the stratum lucidum and forming direct contacts with the system of mossy fibers. Their axons terminate at the proximal portions of dendrites and cell body of pyramidal neurons, occasionally they make contacts with the main cells of the hilus and other hippocampal interneurons. Some portion of axon collaterals is in close vicinity to direct and indirect entorhinal-hippocampal connections, indicating their accommodation to selectively suppress mossy fiber input. The latter form the synapses of various types on the principal cells and on various types of interneurons of area CA 3, indicating different mechanisms of transmitter uptake and presynaptic control of their release.
