Agonist-antagonist properties of fluorescent opioid probes in the guinea-pig myenteric plexus-longitudinal muscle preparation

Summary The behavioral consequences of -adrenoceptor subsensitivity were investigated by determining whether a physiological response that is mediated by -receptors, isoproterenol-induced drinking (IID), would be reduced by subacute antidepressant/ ₂-antagonist treatmentThe coadministration of typical (e.g., imipramine) or atypical (e.g., mianserin) antidepressants with yohimbine or piperoxan twice daily for four consecutive days reduced IID. Both the time course as well as the magnitude of -adrenoceptor subsensitivity could be behaviorally demonstrated. In addition, the reduction in IID observed after coadministration of imipramine with yohimbine was a centrally mediated effect since it was observed after systemic (subcutaneous) and central (intraventricular) administration of isoproterenol. These results provide evidence that IID is an appropriate behavioral model to demonstrate -adrenoceptor subsensitivity following subacute antidepressant/ ₂-antagonist treatment.Paper presented in part at FASEB, St. Louis, MO, USA (Abstract: Fedn Proc 43:941, 1984)