IgE-mediated 14C-serotonin release from rat mast cells modulated by morphine and endorphins

The formaldehyde method was used to examine the interaction of PGE 1 with morphine, β-endorphin and Met-enkephalin on rat mast cells by their effects on IgE-mediated 14C-serotonin release. PGE 1 (2×10 −8−2×10 −5 M) caused a dose-related inhibition of the mediator release 1 min after an antigen challenge, and morphine (3×10 −7−3×10 −5 M) reversed this PGE 1 effect dose-dependently and stereospecifically; naloxone (2×10 −4 M) antagonized this action of morphine. β-Endorphin (3×10 −7−10 −5 M) and Met-enkephalin (3×10 −6−10 −4 M) mimicked this morphine action dose-dependently and were antagonized by naloxone (2×10 −4 M). These results suggest that morphine and endorphins modulate immunological mediator release from rat mast cells through opioid receptors.