The experience of pain is not a benign one. This article reviews evidence that painful experiences, including those associated with surgery, result in a perturbation of the neuroendocrine system, leading to immune suppression and the promotion of pathological processes that are normally resisted by the immune system, such as infection and cancer. Evidence that natural killer (NK) cells control the development of metastasis provides a link between immune function and health outcomes. Using an NK-sensitive tumor model in rats, it was recently shown that the pre- and postoperative administration of an analgesic dose of morphine attenuated the observed surgery-induced increase in metastasis, suggesting that pain relief enabled the host to resist this life-threatening consequence of surgery. Further, other studies have shown that whereas rats become rapidly tolerant to the immune-suppressive and tumor-enhancing effects of morphine, no such tolerance develops to daily exposure to painful footshock stress. Taken together, these findings affirm both the benefits and relative safety of morphine contrasted with the pathogenic nature of pain in this context, thus suggesting that the adequate management of pain must become a vital aspect of health care.
- Immune suppression
ASJC Scopus subject areas
- Clinical Neurology
- Anesthesiology and Pain Medicine