Effects of a single administration of morphine or footshock stress on natural killer cell cytotoxicity

Brain Behav Immun. 1987 Dec;1(4):318-28. doi: 10.1016/0889-1591(87)90034-1.


We previously reported that daily exposure for 4 days to an inescapable form of footshock stress, known to cause opioid-mediated analgesia, suppressed the cytotoxic activity of splenic natural killer (NK) cells in rats. Similarly, daily injection of high doses of morphine (greater than or equal to 30 mg/kg) for 4 days also suppressed splenic NK cell activity. We now report that a single exposure to the opioid form of footshock stress or a single high dose of morphine induces suppression of splenic NK cell cytotoxicity. This effect is evident 3 h after treatment, returning to normal by 24 h. Morphine-induced NK suppression is evident in both male and female rats, is blocked by the opiate antagonist naltrexone, and develops tolerance. Morphine-induced NK suppression is seen in cells derived simultaneously from the spleen, bone marrow, and peripheral blood, suggesting that this suppression does not result from a selective egress of NK cells from the spleen.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cytotoxicity, Immunologic / drug effects
  • Electroshock
  • Female
  • Immunosuppression
  • Killer Cells, Natural / drug effects*
  • Killer Cells, Natural / immunology
  • Morphine / pharmacology*
  • Naltrexone / pharmacology
  • Rats
  • Rats, Inbred F344
  • Spleen / cytology
  • Spleen / drug effects
  • Spleen / immunology
  • Stress, Physiological / immunology*


  • Naltrexone
  • Morphine