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Mu-Opioid Receptors in Ganglia, But Not in Muscle, Mediate Peripheral Analgesia in Rat Muscle Pain.
- Source :
-
Anesthesia and analgesia [Anesth Analg] 2018 Apr; Vol. 126 (4), pp. 1369-1376. - Publication Year :
- 2018
-
Abstract
- Background: Previous studies have demonstrated the participation of peripheral μ-opioid receptors (MOR) in the antinociceptive effect of systemically administered morphine and loperamide in an orofacial muscle pain model, induced by hypertonic saline, but not in a spinally innervated one, in rats. In this study, we determine whether this peripheral antinociceptive effect is due to the activation of MOR localized in the muscle, ganglia, or both.<br />Methods: To determine the local antinociceptive effect of morphine and loperamide, 2 models of acute muscle pain (trigeminal and spinal) were used. Also, to study the MOR expression, protein quantification was performed in the trigeminal and spinal ganglia, and in the muscles.<br />Results: The behavioral results show that the intramuscular injection of morphine and loperamide did not exert an antinociceptive effect in either muscle (morphine: P = .63, loperamide: P = .9). On the other hand, MOR expression was found in the ganglia but not in the muscles. This expression was on average 44% higher (95% confidence interval, 33.3-53.9) in the trigeminal ganglia than in the spinal one.<br />Conclusions: The peripheral antinociceptive effect of systemically administered opioids may be due to the activation of MOR in ganglia. The greater expression of MOR in trigeminal ganglia could explain the higher antinociceptive effect of opioids in orofacial muscle pain than in spinal muscle pain. Therefore, peripheral opioids could represent a promising approach for the treatment of orofacial pain.
- Subjects :
- Acute Pain metabolism
Acute Pain physiopathology
Animals
Disease Models, Animal
Facial Pain metabolism
Facial Pain physiopathology
Ganglia, Spinal metabolism
Ganglia, Spinal physiopathology
Male
Muscle, Skeletal drug effects
Muscle, Skeletal metabolism
Myalgia metabolism
Myalgia physiopathology
Rats, Wistar
Receptors, Opioid, mu metabolism
Trigeminal Ganglion metabolism
Trigeminal Ganglion physiopathology
Acute Pain drug therapy
Analgesics pharmacology
Facial Pain drug therapy
Ganglia, Spinal drug effects
Loperamide pharmacology
Morphine pharmacology
Myalgia drug therapy
Receptors, Opioid, mu drug effects
Trigeminal Ganglion drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 1526-7598
- Volume :
- 126
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Anesthesia and analgesia
- Publication Type :
- Academic Journal
- Accession number :
- 29261544
- Full Text :
- https://doi.org/10.1213/ANE.0000000000002717