Linked Life Data

14718584

Source:http://linkedlifedata.com/resource/pubmed/id/14718584

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2004-3-29
pubmed:abstractText
It is well known that the analgesic potency of morphine is reduced in neuropathic pain. In this study, we demonstrate that the decreased effectiveness of systemic morphine in neuropathic pain might be caused by the loss of morphine analgesia at the periphery. When given s.c. or i.t., the dose-response curves for morphine analgesia in Hargreaves thermal test were shifted rightward in partial sciatic nerve-injured mice compared with control sham-operated mice. The dose-response curves for i.c.v. morphine analgesia, however, were unchanged in nerve-injured mice, indicating no decrease in morphine potency at the supraspinal level. On the other hand, the dose-dependent analgesia produced by intraplantar (i.pl.) morphine in sham-operated mice almost completely disappeared in nerve-injured mice. With the more sensitive algogenic-induced nociceptive flexion test, significant reduction in the analgesic potency of systemic morphine was observed for bradykinin (BK) nociception in nerve-injured mice, and the analgesic effect of i.pl. morphine against BK nociception in sham-operated mice disappeared in nerve-injured mice. In immunohistochemical experiments, we found that, under normal state, mu-opioid receptors (MOPs) were mainly expressed in small-diameter unmyelinated dorsal root ganglion (DRG) neurons and colocalized with bradykinin B2 receptors. When we examined MOP expression in the DRG of nerve-injured mice, we observed a drastic decrease in MOP expression. Altogether, these data suggest that the lower potency of systemic morphine in neuropathic pain could be at least partly caused by the decreased MOP expression in DRG and subsequent loss of peripheral morphine analgesia in such a condition.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-3565
pubmed:author
pubmed:issnType
Print
pubmed:volume
309
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
380-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Loss of peripheral morphine analgesia contributes to the reduced effectiveness of systemic morphine in neuropathic pain.
pubmed:affiliation
Division of Molecular Pharmacology and Neuroscience, Nagasaki University Graduate School of Biomedical Sciences, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't