[In vitro effects of morphine and opioid peptides on neutrophil granulocyte aggregation and ATP release]

The effects of morphine and opioid peptides on neutrophil aggregation and ATP release were studied. Inhibition of human granulocyte aggregation and ATP release was observed in the presence of morphine in a naloxone stereoselective manner, whereas the opioid peptides were ineffective. The effects of DAGO, DADL and Dynorphin 1-9 on the granulocyte aggregation and ATP release were also evaluated, but these opioids peptides are unable to modify neutrophil function. Our studies confirm the role of mu receptors on modulation of polymorphonuclear granulocyte aggregation and suggest a key role of opioid peptides in the regulation of some immune system functions.