Role of Opioid Ligands in the Irritable Bowel Syndrome
Endogenous opioid peptides – enkephalins, beta-endorphin and dynorphins – are located in specific sites of the brain, the spinal cord, the autonomic ganglia and the enteric nervous system. Endogenous opioids participate in the regulation of nervous visceral afference and sensitivity as well as of se...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
1999-01-01
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| Series: | Canadian Journal of Gastroenterology |
| Online Access: | http://dx.doi.org/10.1155/1999/598659 |
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| Summary: | Endogenous
opioid peptides – enkephalins, beta-endorphin and
dynorphins – are located in specific sites of the brain, the spinal
cord, the autonomic ganglia and the enteric nervous system. Endogenous
opioids participate in the regulation of nervous visceral
afference and sensitivity as well as of several visceral motor function
induced by the central nervous system and through the
enteroenteric and the myoenteric reflexes. Their final effect on
gut physiology is the net and harmonically balanced result of their
binding to mu, delta and kappa opioid receptor subtypes. Exogenous
opioid receptor ligands with different affinities for the opioid
receptor subtypes have been effectively used to modify and normalize
altered gut functions. Themureceptor agonists – morphine
and, to a greater extent, the meperidine congeners diphenoxylate
and loperamide – have been shown to slow gastrointestinal transit
by their effects on the circular and longitudinal muscle of the intestine.
Diphenoxylate and, more efficiently, loperamide, for the
lack of any effect on the central nervous system, have been usefully
employed in the treatment of diarrhea in irritable bowel syndrome
(IBS) patients. Unlike the mu receptor agonists morphine
and loperamide, which invariably stimulate colonic motility,
trimebutine, which has almost equal affinity for mu, delta and
kappa receptors, has no effect on normal colonic activity but reduces
the abnormal increase in postprandial motor activity in IBS
patients and accelerates slow large bowel transit in constipated patients.
Opioid ligands can be usefully employed to normalize altered
visceral sensitivity in IBS patients. The kappa receptor
agonist fedotozine exerts its antinociceptive effect by acting on
peripheral nerve endings of sensory vagal and nonvagal afferent
pathways. Fedotozine has been shown to increase the threshold of
perception to colonic distension in experimental conditions and
to affect favourably symptoms of IBS in clinical trials. |
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| ISSN: | 0835-7900 |