Chronic and acute administration of typical and atypical antidepressants on activity of brain noradrenaline systems in the rat thiopentone anaesthesia model.

A behavioural model sensitive to manipulation of brain noradrenaline systems and with characteristics of beta-receptor mediation has been developed using the duration of thiopentone anaesthesia in the rat. Acute and chronic administration of various antidepressant agents was examined. In the acute phase, (30 min prior to thiopentone) the noradrenaline uptake-inhibiting tricyclic drugs and viloxazine increased anaesthesia duration in a dose-dependent fashion. The atypical antidepressants trazodone, iprindole, and mianserin did this only weakly, while the dopaminergic and serotonergic uptake-inhibiting antidepressants (respectively bupropion, nomifensine, and zimelidine, fluoxetine) markedly shortened anaesthesia duration. Chronic administration (for 15 days) prolonged anaesthesia duration measured 2 or 5 days after the last drug injection for all tricyclic agents, for the atypical antidepressants mianserin, iprindole, fluoxetine, and zimelidine, and for viloxazine.