Vol 3, No 2 (2004): Polish Palliative Medicine
Artykuły poglądowe
Published online: 2004-04-09
Peripheral opioid analgesia
Wiebke Janson, Christoph Stein
Advances in Palliative Medicine 2004;3(2):119-130.
Vol 3, No 2 (2004): Polish Palliative Medicine
Artykuły poglądowe
Published online: 2004-04-09
Abstract
Opioids have long been thought to act exclusively within the central nervous system. An increasing number
of studies have recently reported the existence of opioid receptors outside the central nervous system and
therefore suggested that opioids are also able to produce analgesic effects in the periphery. Such effects are
particularly prominent under painful inflammatory conditions both in animals and in humans. During
inflammatory processes opioid receptors are transported from dorsal root ganglia towards the peripheral
sensory nerve endings. At the same time, immune cells containing endogenous opioid peptides accumulate
within the inflamed tissue. Environmental stimuli (e.g. stress) as well as releasing agents (e.g. corticotropin
releasing factor, cytokines) can liberate these opioid peptides to interact with the neuronal opioid receptors
and elicit local analgesia.
The inflammation-induced activation of opioid production and the release of exogenous opioids from
immune cells may lead to novel approaches for the development of peripherally acting analgesics. Clinical
investigation now focuses on the development of new peripheral opioid agonists as well as on ways to
stimulate the endogenous analgesic system in order to induce effective peripheral analgesia with a reduction
in the central side effects typically associated with opioids.
Abstract
Opioids have long been thought to act exclusively within the central nervous system. An increasing number
of studies have recently reported the existence of opioid receptors outside the central nervous system and
therefore suggested that opioids are also able to produce analgesic effects in the periphery. Such effects are
particularly prominent under painful inflammatory conditions both in animals and in humans. During
inflammatory processes opioid receptors are transported from dorsal root ganglia towards the peripheral
sensory nerve endings. At the same time, immune cells containing endogenous opioid peptides accumulate
within the inflamed tissue. Environmental stimuli (e.g. stress) as well as releasing agents (e.g. corticotropin
releasing factor, cytokines) can liberate these opioid peptides to interact with the neuronal opioid receptors
and elicit local analgesia.
The inflammation-induced activation of opioid production and the release of exogenous opioids from
immune cells may lead to novel approaches for the development of peripherally acting analgesics. Clinical
investigation now focuses on the development of new peripheral opioid agonists as well as on ways to
stimulate the endogenous analgesic system in order to induce effective peripheral analgesia with a reduction
in the central side effects typically associated with opioids.
Keywords
peripheral opioid analgesia; inflammation; exogenous analgesia; endogenous analgesia; nociceptin/ORL system; endomorphins; immune modulation of pain
Keywords
peripheral opioid analgesia
inflammation
exogenous analgesia
endogenous analgesia
nociceptin/ORL system
endomorphins
immune modulation of pain
Authors
Wiebke Janson
Christoph Stein