IMMUNOMODULATORY ACTION OF CLASS MU-OPIOID, DELTA-OPIOID AND KAPPA-OPIOID RECEPTOR AGONISTS IN MICE

Endogenous opioids exert a variety of functions outwith the central ne rvous system, including modulation of some murine lymphocyte functions . The results of this study indicate that mu-, delta- and kappa-recept or selective agonists are potent in vitro stimulators of mitogen-induc ed proliferation of murine T-lymphocytes. Moreover, the observed enhan cement of mitogen-induced proliferation was reversed by mu-, delta- an d kappa-receptor class selective antagonists, beta-funaltrexamine, ICI 174,864 and nor-binaltorphimine respectively. An additional study has revealed that repeated administration (four injections) of the opioid receptor selective agonists DAGO, DPDPE and U-50488 also enhanced the concanavalin A-induced proliferation of lymphocytes. These results su ggest that there are three classes of opioid receptors on T-lymphocyte s and that all these receptor classes are involved in the stimulation of concanavalin A-induced proliferation.