[Is an alteration of noradrenergic afferents involved in focal epilepsies? (author's transl)]

Abstract

Previous studies have indicated that noradrenergic system could be involved in various models of chemically, electrically or genetically induced epilepsy. The relationship between the development of a chronic cobalt focus in the rat and the alterations of the cortical noradrenergic system has been studied by means of biochemical analysis of the NA cortical content combined with the glyoxylic acid-induced fluorescence method and the micro-iontophoretic technique. It can be suggested that the noradrenergic system may influence the initiation, spread and disappearance of the epileptic syndrome: (1) The beginning of epileptic discharges coincides with a drop in the NA cortical content, with decrease in number of the NA-containing terminals and with a hypersensitivity of the cortical neurons to iontophoretically applied NA. (2) The termination of the epileptic syndrome coincides with an increase in density of the cortical noradrenergic innervation (sprouting) and consequently with an increase in NA cortical concentrations and a return to normal values of the NA threshold of the cortical neurons.