Differential Involvement of Opioid Receptors in Intrathecal Butorphanol-Induced Analgesia: Compared to Morphine

• Published in: Pharmacology, biochemistry and behavior Vol. 59; no. 3; pp. 723 - 727
• Main Authors: Wongchanapai, W, Tsang, B.K, He, Z, Ho, I.K
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-03-1998; Elsevier Science
• Subjects: Analgesics; Analgesics, Opioid - pharmacology; Animals; Antinociceptive; Biological and medical sciences; Butorphanol; Butorphanol - pharmacology; Dose-Response Relationship, Drug; Injections, Spinal; Intrathecal; Male; Medical sciences; Morphine; Morphine - pharmacology; Naltrexone - analogs & derivatives; Naltrexone - pharmacology; Narcotic Antagonists - pharmacology; Neuropharmacology; Pain Measurement - drug effects; Pharmacology. Drug treatments; Rats; Rats, Sprague-Dawley; Receptors, Opioid - drug effects; Antinociceptive; Morphine; Butorphanol; Intrathecal; Rat; Opioid receptor; Rodentia; Opiates; Narcotic analgesic; Intrathecal administration; Analgesia; Vertebrata; Mammalia; Animal; Mechanism of action; Comparative study
• ISSN: 0091-3057; 1873-5177
• DOI: 10.1016/S0091-3057(97)00558-3

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), β-funaltrexamine (β-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 κ > δ ⩾ μ, whereas morphine acts on μ > δ >> κ. These results indicate that the antinociceptive effect of both IT butorphanol and IT morphine are mediated through μ, δ, and κ opioid receptors in different relative orders.