Opioid Peptides Mediate the Suppressive Effect of Stress on Natural Killer Cell Cytotoxicity

TLDR

The study examined NK cell cytotoxicity in rats exposed to two footshock stress paradigms that both cause analgesia, but only one activates opioid pathways. NK cell activity was suppressed by opioid-mediated stress and high‑dose morphine, but not by nonopioid stress, and this suppression was reversed by the opioid antagonist naltrexone, indicating endogenous opioid peptides mediate stress‑induced NK cell suppression.

Abstract

The cytotoxic activity of natural killer cells was investigated in rats subjected to one of two inescapable footshock stress paradigms, both of which induce analgesia, but only one via activation of opioid mechanisms. Splenic natural killer cell activity was suppressed by the opioid, but not the nonopioid, form of stress. This suppression was blocked by the opioid antagonist naltrexone. Similar suppression of natural killer activity was induced by high doses of morphine. These results suggest that endogenous opioid peptides mediate the suppressive effect of certain forms of stress on natural killer cell cytotoxicity.