The pharmacological profile of Org 6906, a potential non-sedative antidepressant that combines monoamine uptake inhibition with alpha 2-adrenolytic activity.

ABSTRACT

(dl)-(5 alpha,8 alpha,9 alpha)-5,8,9,10-Tetrahydro-5,9- methanobenzocycloocten-8-amine hydrochloride (Org 6906) is a potential new antidepressant agent, with a neurochemical profile quite different from that of the classical tricyclic antidepressant drugs. The compound was found active in behavioural tests which are considered to be predictive for antidepressant activity, such as the muricidal test in the rat and the acquired immobility model. Neurochemical studies showed that Org 6906 was an inhibitor of the reuptake of monoamines both in vitro and ex-vivo without having appreciable anticholinergic, antihistaminergic or alpha 1-adrenolytic activity. The facilitatory effect on monoaminergic neurotransmission was confirmed by the reversal of hypothermia induced by reserpine. The drug Org 6906 appeared to have selective alpha 2-adrenolytic properties. It facilitated potassium-stimulated release of noradrenaline from slices of cortex, displaced [3H]rauwolscine and [3H]dihydroergocryptine from their binding sites but only weakly blocked alpha 1-adrenoceptors. The alpha 2-adrenolytic properties were also apparent in behavioural interaction models. The compound antagonized the sleep-inducing effects of clonidine in chicks and mice and it antagonized the mydriasis induced by clonidine in the rat. Finally, it was shown that the two enantiomers of Org 6906 contributed almost equally to the relevant neurochemical and behavioural properties.