Lack of a dopamine autoreceptor selective profile of B-HT 920 in functional in vitro model systems of D2 receptors in rat striatum

B Drukarch, E Schepens, M J Dolleman-Van der Weel, P De Boer, B J Van Vliet, J C Stoof

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Based on the results of in vivo studies, the thiazoloazepine derivative B-HT 920 has been proposed to be a selective agonist of dopamine autoreceptors. In the present study, we investigated the effects of B-HT 920 in two functional in vitro model systems of D2 receptors and compared these effects with the effects of the classical D2 agonist LY 171555. B-HT 920 and LY 171555 concentration dependently inhibited the electrically evoked release of radiolabeled dopamine and acetylcholine and the forskolin-induced stimulation of adenylate cyclase activity in rat striatal tissue slices with comparable efficacies. In striatal tissue slices prepared after 6-hydroxydopamine-induced destruction of dopaminergic terminals, both drugs were still able to inhibit forskolin-stimulated adenylate cyclase activity with a efficacy similar to that in tissue obtained from unlesioned rats. It is concluded that, in vitro, B-HT 920 is an agonist at both presynaptic and 'normosensitive' postsynaptic D2 receptors showing relatively high intrinsic activity.

Original languageEnglish
Pages (from-to)257-69
Number of pages13
JournalEuropean Journal of Pharmacology
Issue number2
Publication statusPublished - 9 Oct 1990

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