Abstract
In the deafferented cat devoid of the complicating effect of extraneous pharmacological agents (anaesthesia, muscle relaxants) the intra-innominate administration of tranylcypromine elicits immediate EEG activation. With high doses (7.5 mg/kg), EEG activation is immediate, intense, and persists for several hours. With lower doses (2.5 mg/kg) this effect is transient (20 seconds), giving way to a long period of deactivation (35–45 minutes), which in turn is followed by a secondary period of activation.
The immediate EEG activating response of tranylcypromine appears to be a direct effect, the secondary delayed phase of EEG activation appears to be an indirect action, such as might be expected from the retarded inactivation of central amines.
Trifluoperazine (2 mg/kg) elicits EEG deactivation with characteristics similar to those observed following the administration of “equi-deactivating” doses of chlorpromazine (5 mg/kg). When both trifluoperazine (2 mg/kg) and tranylcypromine (7.5 mg/kg) are introduced simultaneously, the activating effects of the latter dominate the earlier phases of the recording.
Preliminary experiments in some preparations in which gross unilateral lesions have been made in the mesencephalic tegmentum raises the possibility that this subcortical area may be a possible site for the arousal effect observed following the administration of tranylcypromine.