Open AccessComparison of the Time Course of Morphine’s Analgesic and Immunologic Effects
Author(s) -
C. J. Nelson,
Linda Dykstra,
Donald T. Lysle
Publication year - 1997
Publication title -
anesthesia and analgesia/anesthesia and analgesia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.404
H-Index - 201
eISSN - 1526-7598
pISSN - 0003-2999
DOI - 10.1097/00000539-199709000-00024
Subject(s) - morphine , medicine , analgesic , immune system , nociception , pharmacology , opioid , cytokine , immunology , receptor
Morphine, an opioid analgesic commonly prescribed and abused, produces immune-altering effects. Whether morphine's antinociceptive and immunologic effects occur concurrently is unknown. Therefore, we investigated the time course of morphine's immunologic and antinociceptive effects. Rats were given a 15-mg/kg morphine injection (subcutaneously), and experimental assessments were taken at 30 min, 1 h, 2 h, 6 h, 12 h, and 24 h after treatment. Immune measures included natural killer (NK) cell activity, proliferation of splenic T and B lymphocytes, and cytokine production. Antinociception was assessed by using the tail withdrawal assay. Results show that morphine's immunomodulatory effects on NK cell activity begin within 30 min, continue for at least 12 h, and return to control values by 24 h. In contrast, proliferation of splenic T and B cells and interferon-gamma production are not altered within 30 min; maximal suppression occurs at 1 h, and recovery begins within 2 h. In all immune measures, therefore, maximal suppression is present at the 1-h time point, and recovery is complete within 24 h. Morphine induces antinociception 30 min to 2 h after drug administration; recovery is complete within 6 h. These results suggest the possibility that different mechanisms modulate morphine's immunologic and analgesic effects.