Journal article
Chronic Muscle Pain Induced by Repeated Acid Injection Is Reversed by Spinally Administered μ- and δ-, but Not κ-, Opioid Receptor Agonists
The Journal of pharmacology and experimental therapeutics, Vol.302(3), pp.1146-1150
09/01/2002
DOI: 10.1124/jpet.102.033167
PMID: 12183674
Abstract
Opioids are commonly used for pain relief clinically and reduce hyperalgesia in most animal models. Two injections of acidic saline into one gastrocnemius muscle 5 days apart produce a long-lasting bilateral hyperalgesia without associated tissue damage. The current study was undertaken to assess the effects of opioid agonists on mechanical hyperalgesia induced by repeated intramuscular injections of acid. Morphine (mu-agonist), [D-Ala(2),N-Me-Phe(4),Gly-ol(5)]-enkephalin (mu-agonist; DAMGO), 4-[((alpha)R)-alpha-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide (delta-agonist; SNC80), or (1S-trans)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cylcohexyl]-benzeneacetamide hydrochloride (kappa-agonist; U50,488) were administered intrathecally to activate opioid receptors once hyperalgesia was developed. Mechanical hyperalgesia was assessed by measuring the withdrawal thresholds to mechanical stimuli (von Frey filaments) before the first and second intramuscular injection, 24 h after the second intramuscular injection, and for 1 h after administration of the opioid agonist or vehicle. Morphine, DAMGO, and SNC80 dose dependently increased the mechanical withdrawal threshold back toward baseline responses. The reduction in hyperalgesia produced by morphine and DAMGO was prevented by H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH(2) (CTAP) and that of SNC80 was prevented by naltrindole. U50,488 had no effect on the decreased mechanical withdrawal thresholds. Thus, activation of mu- and delta-, but not kappa-, opioid receptors in the spinal cord reduces mechanical hyperalgesia following repeated intramuscular injection of acid, thus validating the use of this new model of chronic muscle pain.
Details
- Title: Subtitle
- Chronic Muscle Pain Induced by Repeated Acid Injection Is Reversed by Spinally Administered μ- and δ-, but Not κ-, Opioid Receptor Agonists
- Creators
- K. A SlukaJ. J RohlwingR. A BusseyS. A EikenberryJ. M Wilken
- Resource Type
- Journal article
- Publication Details
- The Journal of pharmacology and experimental therapeutics, Vol.302(3), pp.1146-1150
- DOI
- 10.1124/jpet.102.033167
- PMID
- 12183674
- ISSN
- 0022-3565
- eISSN
- 1521-0103
- Language
- English
- Date published
- 09/01/2002
- Academic Unit
- Iowa Neuroscience Institute; Nursing; Physical Therapy and Rehabilitation Science; Neuroscience and Pharmacology
- Record Identifier
- 9984040355302771
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