title: The inhibitory effect of locally injected dexmedetomidine on carrageenan-induced nociception in rats.
abstract: Recent studies showed that the administration of dexmedetomidine relieved hyperalgesia in the presence of neuropathic pain. These findings have led to the hypothesis that the local administration of dexmedetomidine is useful for relieving acute inflammatory nociception, such as postoperative pain. Thus, we evaluated the inhibitory effect of locally injected dexmedetomidine on acute inflammatory nociception. Acute inflammatory nociception was induced by an intraplantar injection of 1% carrageenan into the hindpaws of rats, and dexmedetomidine was also injected combined with carrageenan. The paw withdrawal threshold based on von Frey filament stimulation was measured until 12 h after injection. We compared the area under the time-curve (AUC) between carrageenan and carrageenan with dexmedetomidine. To clarify that the action of dexmedetomidine was via α2-adrenoceptors, we evaluated the effect of yohimbine, a selective antagonist of α2-adrenoceptors, on the anti-nociception of dexmedetomidine. As the results, the intraplantar injection of carrageenan with over 10 μM dexmedetomidine significantly increased AUC, compared to that with only carrageenan injection. This effect of dexmedetomidine was reversed by the addition of yohimbine to carrageenan and dexmedetomidine. These results demonstrated that the locally injected dexmedetomidine was effective against carrageenan-induced inflammatory nociception via α2-adrenoceptors. The findings suggest that the local injection of dexmedetomidine is useful for relieving local acute inflammatory nociception.
authors.affiliation: Department of Dental Anesthesiology and Special Care Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Honda
authors.affiliation: Department of Dental Anesthesiology, Okayama University Hospital, Okayama 700-8525, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Higuchi
authors.affiliation: Department of Anesthesiology and Resuscitology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Matsuoka
authors.affiliation: Department of Dental Anesthesiology, Okayama University Hospital, Okayama 700-8525, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Yabuki-Kawase
authors.affiliation: Department of Dental Anesthesiology, Okayama University Hospital, Okayama 700-8525, Japan.
authors.forename: Minako
authors.initials: M
authors.lastname: Ishii-Maruhama
authors.affiliation: Department of Dental Anesthesiology and Special Care Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Tomoyasu
authors.affiliation: Department of Dental Anesthesiology, Okayama University Hospital, Okayama 700-8525, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Maeda
authors.affiliation: Department of Anesthesiology and Resuscitology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Morimatsu
authors.affiliation: Department of Dental Anesthesiology and Special Care Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan. Electronic address: miyawaki@md.okayama-u.ac.jp.
authors.forename: Takuya
authors.initials: T
authors.lastname: Miyawaki
mesh_terms: D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D018712:Analgesics, Non-Narcotic / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology / Q000627:therapeutic use*; D002351:Carrageenan; D020927:Dexmedetomidine / Q000494:pharmacology / Q000627:therapeutic use*; D006930:Hyperalgesia / Q000139:chemically induced / Q000188:drug therapy*; D007267:Injections; D008297:Male; D059225:Nociception / Q000187:drug effects; D017207:Rats, Sprague-Dawley; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058669:Adrenergic alpha-2 Receptor Antagonists; D018712:Analgesics, Non-Narcotic; D000893:Anti-Inflammatory Agents; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine; D020927:Dexmedetomidine; D002351:Carrageenan
keywords: Anti-nociception; Dexmedetomidine; Inflammatory pain; Pain relief; α(2)-Adrenoceptors