Differential involvement of opioid receptors in intrathecal butorphanol-induced analgesia: compared to morphine.
The present experiments were performed to investigate the differential involvement of the opioid receptor subtypes in the antinociception of intrathecal (IT) butorphanol compared to IT morphine. A single dose (26 nmol) of IT nor-binaltorphimine (nor-BNI), beta-funaltrexamine (beta-FNA), and naltrindole (NTI) demonstrated a significant attenuation in the overall antinociception of IT butorphanol (52 nmol) or IT morphine (26 nmol). However, IT butorphanol elicits thermal antinociceptive effect through kappa > delta > or = mu, whereas morphine acts on mu >delta >> kappa. These results indicate that the antinociceptive effect of both IT butorphanol and IT morphine are mediated through mu, delta, and kappa opioid receptors in different relative orders.
Wongchanapai
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Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216, USA.
Tsang
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D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D002077:Butorphanol / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007278:Injections, Spinal; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000187:drug effects*
D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; C051844:norbinaltorphimine; D009271:Naltrexone; C024524:beta-funaltrexamine; D009020:Morphine; C055382:naltrindole; D002077:Butorphanol