Activation of spinal orexin-1 receptor produces anti-allodynic effect in the rat carrageenan test.
Orexin-A and orexin-1 receptors are found in the dorsal root ganglion cells and the spinal dorsal horn and this suggests that orexin-A is involved in the spinal nociceptive transmission. The authors examined the effect of intrathecally administered orexin-A on the level of mechanical allodynia and thermal hyperalgesia induced by paw carrageenan injection in the rat. Intrathecal injection of 0.3 and 3 nmol of orexin-A suppressed the level of mechanical allodynia, but not that of thermal hyperalgesia, and the effect of orexin-A on mechanical allodynia was antagonized by the pretreatment of 1-(2-methylbenzoxazol-6-yl)-3-[1,5]naphthyridin-4-yl urea hydrochloride, SB-334867, a selective orexin-1 receptor antagonist. These data suggest that the activation of spinal orexin-1 receptor modulates the mechanical information transmission, but not thermal information transmission, in the spinal cord during carrageenan test.
Yamamoto
Tatsuo
T
Department of Anesthesiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo, Chiba-shi, Chiba 260-8670, Japan. yamamoto@faculty.chiba-u.ac.jp
Saito
Osamu
O
Shono
Koyo
K
Hirasawa
Serabi
S
D000818:Animals; D002351:Carrageenan / Q000633:toxicity*; D002352:Carrier Proteins / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006358:Hot Temperature / Q000009:adverse effects; D006930:Hyperalgesia / Q000139:chemically induced / Q000378:metabolism; D007278:Injections, Spinal; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology; D064446:Orexin Receptors; D000068797:Orexins; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods*; D010812:Physical Stimulation / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide / Q000819:agonists / Q000378:metabolism*; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D002351:Carrageenan