beta-carboline binding to imidazoline receptors

A series of beta -carbolines were prepared and their affinities for imidazo line (I-1 and I-2) sites evaluated. Selected compounds were also examined a t alpha (2)-adrenoceptors. Some of the beta -carbolines were found to bind with high affinity to I-2-sites and this affinity was dependent on both the planarity of the molecule and the presence of the aryl ring substituents. Good I-1-affinity was observed with two of the compounds but none of the te sted compounds bound to alpha (2)-adrenoceptors. The hallucinogenic propert ies of beta -carbolines have been linked to activity at 5-HT receptors, in particular 5-HT2, however, it is apparent from this study that many of thes e compounds display substantially higher affinity for the imidazoline sites . This finding, and those showing modulation of some behavioural effects of morphine by I-2-ligands, suggests that imidazoline sites may be interestin g new targets in drug abuse research. (C) 2001 Elsevier Science Ireland Ltd . All rights reserved.