Abstract
We previously reported that a single systemic injection of a high dose of morphine (≥20 mg/kg) transiently suppresses splenic natural killer cell cytotoxicity in rats. The present study examined the possibility that the immune-suppressive effect of morphine is mediated by opiate receptors in the brain. Supporting this hypothesis, we found that morphine (20 or 40 μg) injected into the lateral ventricle suppressed natural killer cell activity to the same degree as a systemic dose higher by three orders of magnitude. This effect was blocked by an opiate antagonist, naltrexone. Natural killer cell activity was unaffected by systemic administration of N-methylmorphine, a morphine analogue that does not cross the blood-brain barrier. These data implicate opiate receptors in the brain in morphine-induced suppression of natural killer cell cytotoxicity.
Original language | English |
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Pages (from-to) | 7114-7117 |
Number of pages | 4 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 83 |
Issue number | 18 |
DOIs | |
State | Published - 1986 |
Externally published | Yes |