[Study of histoenzymologic signs of selective neuronal hyperactivity]. / A la récherche de signes histoenzymologiques d'une hyperactivité neuronale sélective.

Injection of kainic acid into the cerebellum leads to a neuroexcitatory and neurotoxic effect on neurons connected with cerebellar granule cells. Observation of the activities of dehydrogenases taking part in glucose metabolism and glutamate dehydrogenase shows that Purkinje cells undergo a rapid destruction. Lesions of small stellate cells come later. But the basket cells present a long period of hyperactivity revealed by an increase of dehydrogenase activity.

[Retrogression of the metabolic activity of astrocytes after extinction of an experimental epileptogenic focus. Histochemical investigation]. / Régression de l'activation métabolique des astrocytes après extinction du foyer épileptogène expérimental. Etude histochimique.

Previous anatomochemical and experimental investigations had resulted in the histochemical characterisation of the epileptogenic focus by the presence of "activated astrocytes"; cortical reactive astrocytes acquiring an intense activity of sundry dehydrogenases (DH) and becoming visible in spite of the positivity of the neuropil, and stopping at the amylose step in the synthesis of glycogen. This activation exists from the first electrical sings of epilepsy and even preceeds them in the case of glucose-6-phosphate DH. The present study deals with the fate of activated astrocytes after the disappearance of electrical signs of the epileptogenic focus produced by implantation of a cobalt powder-gelatin pellet into the cerebral cortex of the rat. After extinction of the focus, high activity of DH persists in astrocytes only in the immediate vicinity of the glial scar surrounding the implant. Later, among the DH investigated only glutamate and specially glucose-6-phosphate DH maintain an activity intense enough to reveal these cells on the background of the neuropil. These results point to a progressive return to a normal metabolism of astrocytes after the disappearance of the electrical signs of epilepsy by way of steps similar to those preceeding these signs.

[The activity of cytochrome oxidase in the normal cerebral cortex and after destructive and irritating lesions. Histochemical research]. / Activité de la cytochrome oxydase dans le cortex cérébral normal et après lésions destructives et irritatives (recherches histochimiques).

Production of an epileptogenic focus by cobalt-gelatin implantation in the cerebral cortex of the rat determines a local increase of cytochrome oxidase activity in neurones and probably a decrease of its activity in neuroglia. This variation of oxidative metabolism is not characteristic of the "epileptic neuron" since it takes also place after non irritative lesions, though remaining less conspicuous and less extensive.