TY - JOUR
T1 - Inflammation enhances peripheral μ-opioid receptor-mediated analgesia, but not μ-opioid receptor transcription in dorsal root ganglia
AU - Schäfer, Michael
AU - Imai, Yasuo
AU - Uhl, George R.
AU - Stein, Christoph
PY - 1995/6/12
Y1 - 1995/6/12
N2 - μ-Opioid receptor agonist [d-Ala2,NMe-Phe4,Gly5-ol]enkephalin (DAMGO)-induced peripheral analgesic effects occur early in hindpaws inoculated with Freund's complete adjuvant and increase in parallel to the development of inflammatory signs. Antagonism of these effects by β-funaltrexamine, an irreversible μ-opioid receptor antagonist, suggests that the effective number of peripheral opioid receptors does not increase during early stages, but does so at later stages of the inflammation. As determined by a ribonuclease protection assay, μ-opioid receptor mRNA in dorsal root ganglia is abundant in untreated animals, but does not significantly increase following inflammation. Thus, peripheral analgesic efficacy of DAMGO is not correlated with transcription or number of μ-opioid receptors at early inflammatory stages. At later stages, however, the number of peripheral μ-opioid receptors appears to increase and may enhance opioid efficacy.
AB - μ-Opioid receptor agonist [d-Ala2,NMe-Phe4,Gly5-ol]enkephalin (DAMGO)-induced peripheral analgesic effects occur early in hindpaws inoculated with Freund's complete adjuvant and increase in parallel to the development of inflammatory signs. Antagonism of these effects by β-funaltrexamine, an irreversible μ-opioid receptor antagonist, suggests that the effective number of peripheral opioid receptors does not increase during early stages, but does so at later stages of the inflammation. As determined by a ribonuclease protection assay, μ-opioid receptor mRNA in dorsal root ganglia is abundant in untreated animals, but does not significantly increase following inflammation. Thus, peripheral analgesic efficacy of DAMGO is not correlated with transcription or number of μ-opioid receptors at early inflammatory stages. At later stages, however, the number of peripheral μ-opioid receptors appears to increase and may enhance opioid efficacy.
KW - Antinociception
KW - Dorsal root ganglion
KW - Primary afferent neuron
KW - Ribonuclease protection assay
KW - β-Funaltrexamine
KW - μ-Opioid receptor
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U2 - 10.1016/0014-2999(95)00150-J
DO - 10.1016/0014-2999(95)00150-J
M3 - Article
C2 - 7556397
AN - SCOPUS:0029047619
SN - 0014-2999
VL - 279
SP - 165
EP - 169
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
IS - 2-3
ER -