Paper Information

Title:  THE ROLE OF C-FIBERS, ULTRA LOW DOSE AND USUAL DOSE OF MORPHINE ON PAW INFLAMMATION INDUCED BY FORMALIN
Type: POSTER
Author(s): FEREYDOUNI MASOUD*,ALIZADEH ZAHRA,BEHNAM RASOULI MORTEZA
 
 *DEPARTMENT OF BIOLOG, SCHOOL OF SCIENCES, MASHHAD FERDOWSI UNIVERSITY, MASHHAD, IRAN
 
Name of Seminar: IRANIAN CONGRESS OF PHYSIOLOGY AND PHARMACOLOGY
Type of Seminar:  CONGRESS
Sponsor:  PHYSIOLOGY AND PHARMACOLOGY SOCIETY, MASHHAD UNIVERSITY OF MEDICAL SCIENCE
Date:  2009Volume 19
 
 
Abstract: 

It has been proved that morphine has anti-inflammatory effect at usual dose such as 10 mg/kg. Regarding the role of C-fibers on inflammation augmented by peripheral release of SP and CGRP and inhibitory action of opioid receptors on these fibers and based on reports which show the stimulatory effects of ultra low dose morphine on afferent C-fibers, present research was established to study the role of C-fibers, usual dose and ultra low dose of morphine in presence or reduced C-fibers on paw inflammation edema induced by subplantar injection of formalin. Adult Wistar male rats weighting 180-200 g were used (n=7). Adults animals were assigned in two groups: sham-control (which received capsaicin vehicle at neonatl stage: C-normal) and experimental (received neonatal capsaicin: C-lesion). 30 minutes before subplantar injection of formalin (2.5%, 0.05% cc for edema induction), each subgroup was treated by a single dose of saline and or 10 mg/kg or 1μg/kg morphine separately. The results of paw edema volume assessments were compared between the groups. In C-normal group morphine showed an anti-inflammatory effect at the dose of 10 mg/kg but showed pro-inflammatory effect at the dose of 1μg/kg (p<0.05). Reduction of the C-fibers diminished the edema induced by formalin (p<0.001). In the Clesion group, 10 mg/kg morphine showed a more potent anti-inflammatory effect (p<0.001) and the pro-inflammatory effect of 1μg/kg morphine was disappeared (p<0.01). C-fibers using SP and CGRP release can play an important role in anti-inflammatory induction in injured tissues. So it could be supposed that Cfibers reduction, could diminish the inflammation, our results show that the presence of C-fibers are so important on inflammation induction, as the C-fibers reduction, diminished the inflammation. Furthermore, morphine which shows anti-inflammatory effect at usual doses can show more potent anti-inflammatory effect in C-lesion group, so there is not the only inhibitory effect of morphine on C-fibers which induce the anti-inflammatory effect of morphine, in this regard it would be better to have a consideration on morphine effects on tissue immune cells also. Hyperalgesic effect of ultra low doses of morphine via C-fibers stimulation have been reported, so the alleviation of the inflammatory mediators in the tissues followed by C-fibers stimulation is expected, as ultra low dose of morphine lost its pro-inflammatory effect after reduction of Cfibers.

 
Keyword(s): CAPSAICIN, C-FIBERS, FORMALIN TEST, MORPHINE, INFLAMMATION
 
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