Behavioural reactions and changes in the spontaneous and evoked EEG-activity upon microinjection of noradrenaline and isoprenaline in cat nucleus raphe dorsalis.

Experiments are carried out on five cats with bipolar electrodes chronically implanted in various brain structures. The electrode intended to be introduced into raphe dorsalis is placed in a "guiding" isolated cannule. The spontaneous EEG-activity, the evoked potentials of photo- and electrostimulation as well as the behavioural reactions are studied for each animal before and after administration of noradrenaline (NA), isoprenaline (ISO) respectively, into nucleus raphe dorsalis (RD). The evoked potential are tape-recorded and averaged on Nicolet--1072 computer. Administration of NA in cat RD is followed by manifestations characterized by vegetative and motor symptoms and accompanied by EEG-changes. Desynchronization develops immediately after the injection of both NA and ISO in RD. The restoration of the amplitude-frequency characteristics of the EEG-activity take place in RD at the latest. Considerable changes are also observed in the evoked potentials recorded from the different structures. The EEG-changes observed after injection of NA, respectively ISO, in RD suggest functional connections between RD and the other brain structures studied. Both the EEG-changes and the observed behavioural reactions are probably largely based on the inhibition of the cerebral serotonin tonus by the catecholamines NA and ISO injected into RD and the resulting disruption of the balance between the adrenergic and serotoninergic cerebral systems.