scholarly journals Local administration of mu or kappa opioid agonists attenuates capsaicin-induced thermal hyperalgesia via peripheral opioid receptors in rats

2000 ◽  
Vol 148 (2) ◽  
pp. 180-185 ◽  
Author(s):  
M. C. H. Ko ◽  
J. E. Tuchman ◽  
M. D. Johnson ◽  
K. Wiesenauer ◽  
J. H. Woods ◽  
...  
Keyword(s):  
Opioid Receptors ◽  
Thermal Hyperalgesia ◽  
Local Administration ◽  
Kappa Opioid ◽  
Opioid Agonists ◽  
Peripheral Opioid Receptors

EVIDENCE FOR A CENTRAL OPIOID CONTROL OF RUMINATION

1984 ◽  
Vol 64 (5) ◽  
pp. 13-15 ◽  
Author(s):  
Y. RUCKEBUSCH ◽  
TH. BARDON
Keyword(s):  
Key Words ◽  
Opioid Receptor ◽  
Opioid Receptors ◽  
Opioid Peptides ◽  
Kappa Opioid Receptor ◽  
Kappa Opioid ◽  
Receptor Agonists ◽  
Opioid Agonists ◽  
Reflex Control ◽  
Opioid Receptor Agonists

Intravenous adrenaline induced reticular extracontractions and rumination within 26 sec in hay-fed, and 184 sec in cube-fed sheep. Regardless of diet, pretreatment with cerebroventricular infusion of kappa-opioid-receptor agonists enhanced this reflex. Control of rumination may involve multiple opioid-receptors, since inhibition of the reflex occurred after mu- and delta-opioid-agonists. Key words: Sheep, rumination, opioid-peptides

Central and systemic kappa-opioid agonists exacerbate neurobehavioral response to brain injury in rats

1994 ◽  
Vol 267 (3) ◽  
pp. R665-R672
Author(s):  
T. K. McIntosh ◽  
S. Fernyak ◽  
I. Yamakami ◽  
A. I. Faden
Keyword(s):  
Brain Injury ◽  
Opioid Receptors ◽  
Tissue Injury ◽  
Motor Deficits ◽  
Dynorphin A ◽  
Endogenous Opioid ◽  
Kappa Opioid ◽  
Endogenous Opioid Peptide ◽  
Opioid Agonists ◽  
Cns Trauma

The endogenous opioid peptide dynorphin has been implicated in the pathophysiology of secondary tissue injury after central nervous system (CNS) trauma. The detrimental effects of dynorphin appear to be mediated through both opioid receptors (probably kappa-receptors) and nonopioid mechanisms. However, both kappa-opioid agonists and antagonists have been reported to improve outcome in models of CNS trauma. To attempt to clarify this controversy, we examined the effects of centrally or systemically administered kappa-opioid agonists on neurological recovery after experimental fluid-percussion brain injury in the rat. Agonists included dynorphin A-(1-17) [Dyn A-(1-17)], which has actions at both kappa 1- and kappa 2-sites, and the selective kappa 1-agonists U-50,488H and U-69,593. des-Tyr-dynorphin A-(2-17) [Dyn A-(2-17)], which is inactive at opioid receptors, was also used. Microinjection of Dyn A-(1-17), but not Dyn A-(2-17) or U-50,488H, into the lateral ventricle 15 min before brain injury significantly worsened motor deficits over a 2-wk period. However, systemic administration of high doses of the kappa-agonists U-50,488H and U-69,593 also significantly worsened neurological outcome. These results fail to demonstrate any protective actions of kappa 1-agonists in this model of experimental traumatic brain injury and suggest that the opioid-related pathophysiological actions of dynorphin may be mediated by kappa 2-opioid receptors.

Morphine Directly Inhibits Nociceptors in Inflamed Skin

2006 ◽  
Vol 95 (4) ◽  
pp. 2083-2097 ◽  
Author(s):  
Heather N. Wenk ◽  
Jill-Desiree Brederson ◽  
Christopher N. Honda
Keyword(s):  
Opioid Receptors ◽  
Average Rate ◽  
Receptive Fields ◽  
Thermal Hyperalgesia ◽  
Experimental Models ◽  
Spontaneous Discharge ◽  
Intraplantar Injection ◽  
Response Properties ◽  
Peripheral Opioid Receptors

Peripherally delivered opiates attenuate mechanical and thermal hyperalgesia in experimental models of inflammation, suggesting that activation of peripheral opioid receptors decreases the excitability of nociceptors in inflamed tissues. The current study examines the effects of peripheral morphine sulfate on response properties of sensory neurons in healthy and inflamed skin. Afferent units (185) were isolated from tibial nerve of rats using an in vitro glabrous skin-nerve teased-fiber preparation. Of these, 107 units were from normal healthy skin, and 78 were from inflamed skin 18 h after intraplantar injection of complete Freund's adjuvant. As a population, C-fiber units innervating inflamed skin exhibited properties characteristic of sensitization when compared with units innervating healthy control skin. Mechanical thresholds were lowered, responses to noxious mechanical and thermal stimuli were elevated, a greater proportion of units was spontaneously active, and the average rate of spontaneous discharge was higher. Response properties in other conduction velocity groups remained unchanged. Fifty-eight percent of C and C/Aδ nociceptors innervating inflamed skin were opiate-sensitive, and their excitability was attenuated by direct application of morphine to their receptive fields. All morphine-sensitive units were nociceptors from inflamed skin with conduction velocities <1.3 m/s. Morphine effects were concentration-dependent and naloxone-sensitive, indicating that the effects were receptor-mediated. These findings provide direct evidence that morphine acts through peripheral opioid receptors to inhibit the activity of cutaneous nociceptors under conditions of inflammation.

scholarly journals Peripherally Acting Opioids and Clinical Implications for Pain Control

2011 ◽  
Vol 3;14 (3;5) ◽  
pp. 249-258
Author(s):  
Nalini Sehgal
Keyword(s):  
Nervous System ◽  
Peripheral Nervous System ◽  
Opioid Receptors ◽  
Opioid Peptides ◽  
Nerve Fibers ◽  
Dorsal Root Ganglion Neurons ◽  
Opioid Agonists ◽  
Anti Inflammatory ◽  
Peripheral Opioid Receptors ◽  
Ganglion Neurons

Opioid receptors are widely expressed in the central and peripheral nervous system and in the non-neuronal tissues. Data from animal and human clinical studies support the involvement of peripheral opioid receptors in analgesia, especially in the presence of inflammation. Inflammation has been shown to increase the synthesis of opioid receptors in the dorsal root ganglion neurons and enhance transport and accumulation of opioid receptors in the peripheral terminals of sensory neurons. Under the influence of chemokines and adhesion molecules, opioid peptide-containing immune cells extravasate and accumulate in the injured tissues. Stress, chemokines, cytokines, and other releasing factors in inflamed tissues stimulate these granulocytes to release opioid peptides. Once secreted, opioid peptides bind to and activate peripheral opioid receptors on sensory nerve fibers and produce analgesia by decreasing the excitability of sensory nerves and/or inhibiting release of pro-inflammatory neuropeptides. Research has revealed that local application of exogenous opioid agonists produces a potent analgesic effect by activating peripheral opioid receptors in inflamed tissues. The analgesic activity occurs without activation of opioid receptors in the central nervous system (CNS), and therefore centrally mediated side effects, such as respiratory depression, mental clouding, altered consciousness, or addiction, are not associated with peripheral opioid activity. This discovery has stimulated research on developing peripherally restricted opioid agonists that lack CNS effects. In addition, it has been recognized that opioid receptors modulate inflammation, and that opioids have antiinflammatory effects. The anti-inflammatory actions of opioids are not well known or understood. Conflicting reports on mu-opioids suggest both anti-inflammatory and pro-inflammatory effects. This article will present the basis for peripheral opioid analgesia and describe current research directed at developing novel treatments for pain with improved side effect profiles. Key words: Opioids, opioid receptors, opioid agonists, peripheral nervous system, peripheral opioid receptors

CHARACTERIZATION OF KAPPA OPIOID RECEPTORS WITH TRITIATED norBNI

Analgesia ◽  
1995 ◽  
Vol 1 (4) ◽  
pp. 557-560 ◽  
Author(s):  
Á Márki ◽  
F. Ötvös ◽  
G. Tóth ◽  
S. Hosztafi ◽  
A. Borsodi
Keyword(s):  
Opioid Receptors ◽  
Kappa Opioid Receptors ◽  
Kappa Opioid

Comparison of Antinociceptive Effects Induced by Kappa Opioid Agonists in Male and Female Mice

Analgesia ◽  
1999 ◽  
Vol 4 (3) ◽  
pp. 397-404 ◽  
Author(s):  
Corinne A. Patrick ◽  
M. C. Holden Ko ◽  
James H. Woods
Keyword(s):  
Kappa Opioid ◽  
Male And Female ◽  
Female Mice ◽  
Opioid Agonists ◽  
Antinociceptive Effects

Kappa opioid agonists alter dopamine markers and cocaine-stimulated locomotor activity

2001 ◽  
Vol 12 (4) ◽  
pp. 237-245 ◽  
Author(s):  
S.L. Collins ◽  
R.M. Gerdes ◽  
C. DʼAddario ◽  
S. Izenwasser
Keyword(s):  
Locomotor Activity ◽  
Kappa Opioid ◽  
Opioid Agonists
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