Opioids and beta-receptors interaction: further studies in cultured cells.

In the present paper a further evidence of a functional link between opioids and beta-receptor system in cultured rat C6 cells is presented. We showed that C6 cell exposure to Desmethylimipramine (DMI) causes expression of opioid receptors and loss of beta-receptors. We now show that C6 cells exposure to DMI causes an increase of intracellular levels of opioid peptides and an increase of aminopeptidase activity. In addition, the presence of the aminopeptidase inhibitor bestatin during cell exposure inhibits DMI-induced beta-receptor loss. These results indicate that cell exposure to DMI causes the full expression of the opioid peptide system. This effect could be related to changes of beta-receptor system.