Pain can be effectively diminished by various endogenous mechanisms within the central
nervous system. One region where these mechanisms have been well characterized is the …

Exogenous opioids can produce localized opioid receptor-mediated antinociception in
peripheral inflamed tissue. Previous studies show that activation of endogenous opioids by …

Recent findings have suggested a significant involvement of the immune system in the
control of pain. Immune cells contain opioid peptides that are released within inflamed tissue …

Recent experimental and clinical research has demonstrated that opioids can produce
potent and receptor-specific analgesic effects outside the central nervous system. Opioid …

This review summarizes recent findings on neuro-immune mechanisms underlying opioid-
mediated inhibition of pain. The focus is on events occurring in peripheral injured tissues …

The origin of the theory that the transmission of pain is through a single channel from the
skin to the brain can be traced to the philosopher and scientist René Descartes. This …

Traditionally, opioid analgesia has been attributed to the activation of opioid receptors
exclusively within the central nervous system. In fact, standard text books still teach medical …

Opioid receptors are widely expressed in the central and peripheral nervous system as well
as in numerous nonneuronal tissues. Both animal models and human clinical data support …

Chronic pain differs from acute pain in that it serves no useful function, causes suffering,
limits activities of daily living, and increases costs of healthcare payments, disability, and …

Opioids have long been thought to act exclusively within the central nervous system. An
increasing number of studies recently reported the existence of opioid receptors outside the …