Differential effects of β-endorphin on cAMP levels in human peripheral blood mononuclear cells

Abstract

In the present paper we demonstrate that one of the early effects of the opioid peptide β-endorphin on human peripheral blood mononuclear cells is the induction of a change in the intracellular cAMP level. However, the effect of β-endorphin on cAMP levels is not uniform; increases as well as decreases in cAMP level are observed. It appears that β-endorphin is a true modulator of intracellular cAMP level: the peptide will increase cAMP levels in cells with a low baseline level. In contrast, β-endorphin tends to decrease cAMP levels in cells with a high cAMP concentration. Moreover, β-endorphin modulates the rise in cAMP induced by β-adrenergic activation. The effect of β-endorphin on cAMP level correlates negatively with the magnitude of the change in cAMP level induced by β-adrenergic activation.