Intracisternal administration of chemokines facilitated formalin-induced behavioral responses in the orofacial area of freely moving rats.
The present study investigated the effects of intracisternal administration of MCP-1, Rantes or IL-8 on pain transmission in the orofacial area. We also investigated mechanisms of hyperalgesic responses produced by intracisternal administration of IL-8. An orofacial formalin test was employed to assess the effects of chemokines on nociceptive processing. For each animal, the number of behavioral responses and the time spent grooming, rubbing and/or scratching the facial region proximal to the formalin injection site was recorded for nine successive 5-min intervals. Intracisternal administration of MCP-1, Rantes or IL-8 significantly increased formalin-induced scratching behavioral responses in the orofacial area. Intracisternal pretreatment with indomethacin, a non-selective cyclooxygenase inhibitor, did not block IL-8-induced hyperalgesia. Pretreatment with 100 microg propranolol, a non-selective beta-adrenergic receptor antagonist and 50 microg atenolol, a selective beta(1)-adrenergic receptor antagonist, inhibited the number of scratches and the duration of scratching produced by 1 ng of IL-8 injected intracisternally. These results indicate that intracisternal administration of chemokines produce a hyperalgesic response with an orofacial inflammatory pain model and that the IL-8-induced hyperalgesia is mediated by central beta(1)-adrenergic receptor.
Ahn
D K
DK
Department of Oral Physiology, School of Dentistry, Kyungpook National University, 188-1 Sam Deok 2ga, Chung-gu, Daegu 700-412, South Korea. dkahn@knu.ac.kr
Lee
K R
KR
Lee
H J
HJ
Kim
S K
SK
Choi
H S
HS
Lim
E J
EJ
Park
J S
JS
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D018932:Chemokine CCL2 / Q000008:administration & dosage; D018946:Chemokine CCL5 / Q000008:administration & dosage; D018925:Chemokines / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005157:Facial Pain / Q000139:chemically induced* / Q000503:physiopathology*; D005557:Formaldehyde / Q000633:toxicity*; D006930:Hyperalgesia / Q000139:chemically induced / Q000503:physiopathology; D016209:Interleukin-8 / Q000008:administration & dosage; D008297:Male; D010147:Pain Measurement / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D014851:Wakefulness / Q000502:physiology*
C491766:Ccl2 protein, rat; D018932:Chemokine CCL2; D018946:Chemokine CCL5; D018925:Chemokines; D016209:Interleukin-8; D005557:Formaldehyde