Repeated Mu-Opioid Exposure Induces a Novel Form of the Hyperalgesic Priming Model for Transition to Chronic Pain.
J Neurosci
; 35(36): 12502-17, 2015 Sep 09.
Article
em En
| MEDLINE
| ID: mdl-26354917
ABSTRACT
The primary afferent nociceptor was used as a model system to study mechanisms of pain induced by chronic opioid administration. Repeated intradermal injection of the selective mu-opioid receptor (MOR) agonist DAMGO induced mechanical hyperalgesia and marked prolongation of prostaglandin E2 (PGE2) hyperalgesia, a key feature of hyperalgesic priming. However, in contrast to prior studies of priming induced by receptor-mediated (i.e., TNFα, NGF, or IL-6 receptor) or direct activation of protein kinase Cε (PKCε), the pronociceptive effects of PGE2 in DAMGO-treated rats demonstrated the following (1) rapid induction (4 h compared with 3 d); (2) protein kinase A (PKA), rather than PKCε, dependence; (3) prolongation of hyperalgesia induced by an activator of PKA, 8-bromo cAMP; (4) failure to be reversed by a protein translation inhibitor; (5) priming in females as well as in males; and (6) lack of dependence on the isolectin B4-positive nociceptor. These studies demonstrate a novel form of hyperalgesic priming induced by repeated administration of an agonist at the Gi-protein-coupled MOR to the peripheral terminal of the nociceptor. Significance statement The current study demonstrates the molecular mechanisms involved in the sensitization of nociceptors produced by repeated activation of mu-opioid receptors and contributes to our understanding of the painful condition observed in patients submitted to chronic use of opioids.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Receptores Opioides mu
/
Dor Crônica
/
Hiperalgesia
Limite:
Animals
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article