A study of bile acids as opioid receptor ligands in rat brain membranes

There is evidence to suggest that the pruritus that results from liver disease is mediated, at least in part, by opioid receptor-ligand interactions; a central component has been proposed. Opiate drugs with agonist activity at opioid receptors induce naloxone-reversible pruritus. Bile acids accumulate in tissues in liver disease. We studied the ability of bile acids to displace specific opioid ligands from opioid receptors in rat and guinea pig brain membrane preparation in binding assays. None of the bile acids studied displaced significantly the opioid ligands from their receptors suggesting that bile acids in vitro are not opioid receptor ligands. The results of this study do not support a role of these bile acids as direct pruritogens by an opioid receptor-mediated mechanism.