Induction of human cutaneous mast cell degranulation by opiates and endogenous opioid peptides: evidence for opiate and nonopiate receptor participation.

In order to examine the capacity of pharmacologically useful opiates to stimulate human mast cell secretion, subjects were skin tested with morphine, codeine, or meperidine hydrochloride. All three agents acted equipotently in eliciting positive immediate skin reactions from all subjects tested. Each agent demonstrated 10 mm of net whealing at 5 to 10 micrograms base (16.7 to 40.4 nmol) injected intradermally. The ability to elicit immediate skin test reactions with endogenous opioid peptides was examined with the use of dynorphin, [D-Ala, 2-D-Leu5] enkephalin, beta-endorphin, and morphiceptin . All four compounds induced wheal-and-flare reactions with the order of potency: dynorphin, greater than beta-endorphin, and greater than [D-Ala, 2-D-Leu5] enkephalin approximately equal to morphiceptin at dose ranges of 0.3 to 8.45 nmol. The inhibition of reactivity by hydroxyzine and the demonstration of mast cell degranulation by electron microscopy suggest that the immediate skin responses to opioid stimulation occur as a consequence of mast cell degranulation. Experiments with the opioid receptor antagonist, naloxone, suggest that both opioid and nonopioid receptors may be involved. These results imply that endogenous opioid peptides possibly may play a role in mast cell function and/or degradulation .