Document Detail


Evaluation of pseudo-affective responses to noxious colorectal distension in rats by manometric recordings.
MedLine Citation:
PMID:  15936885     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Recordings of electromyographic (EMG) activity in the abdominal musculature are generally used to quantify the pseudo-affective visceromotor response induced by colorectal distension (CRD) in rodents. The present study describes a non-invasive, manometric method to quantify the magnitude of the abdominal contractions evoked by CRD. CRD-induced increases in EMG activity in female rats (electrical response) were compared to phasic changes in balloon pressure (mechanical response). A phasic increasing CRD paradigm from 10 to 80mmHg with 10mmHg intervals induced a clear stimulus-response relationship with a strong correlation (r(2)=0.93) between the electrical and mechanical responses. Twelve repeated phasic distensions at 80mmHg increased the mechanical response by 133+/-53% (P<0.01), while the electrical response only increased by 20+/-19% (P>0.05), when comparing the last distension to the first. Atropine methyl bromide (1mg/kg, i.v.) did not affect the mechanical response to distension at 80mmHg, suggesting that colonic activity per se, does not contribute to the balloon pressure variations during CRD in the current experimental set-up. The mu-opioid receptor agonist fentanyl at a dose of 1.5microg/kg (i.v.) significantly reduced the mechanical response to CRD (P<0.01) while the electrical response was not affected. The present study shows that phasic bursts in EMG activity from the abdominal musculature occur simultaneously with balloon pressure variations, which may represent a non-invasive alternative to EMG recordings. Furthermore, the mechanical response is a more sensitive parameter for detecting both hyperalgesic and analgesic responses.
Authors:
Anna Tammpere; Mikael Brusberg; Jan Axenborg; Ika Hirsch; Håkan Larsson; Erik Lindström
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Publication Detail:
Type:  Comparative Study; Evaluation Studies; Journal Article    
Journal Detail:
Title:  Pain     Volume:  116     ISSN:  0304-3959     ISO Abbreviation:  Pain     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-07-11     Completed Date:  2005-10-11     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7508686     Medline TA:  Pain     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  220-6     Citation Subset:  IM    
Affiliation:
AstraZeneca R&D, Integrative Pharmacology, GI Biology, S-431 83 Mölndal, Sweden.
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MeSH Terms
Descriptor/Qualifier:
Analysis of Variance
Animals
Atropine Derivatives / pharmacology
Colon / drug effects,  physiology*
Dilatation, Pathologic / drug therapy,  physiopathology*
Dose-Response Relationship, Drug
Dose-Response Relationship, Radiation
Electromyography / methods
Female
Fentanyl / pharmacology
Muscle Contraction / drug effects,  physiology
Narcotics / pharmacology
Nociceptors / drug effects,  physiology*
Pain Measurement / methods*
Parasympatholytics / pharmacology
Physical Stimulation / methods
Pressure
Rats
Rats, Sprague-Dawley
Sensory Thresholds / drug effects,  physiology,  radiation effects
Chemical
Reg. No./Substance:
0/Atropine Derivatives; 0/Narcotics; 0/Parasympatholytics; 31610-87-4/methylatropine; 437-38-7/Fentanyl

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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