Central cyclooxygenase-2 participates in interleukin-1 beta-induced hyperalgesia in the orofacial formalin test of freely moving rats.
The present study was performed to investigate effects of central cyclooxygenase (COX) on interleukin (IL)-1beta-induced hyperalgesia in the orofacial area. Experiments were carried out on 72 male Sprague-Dawley rats weighing 220-280 g. Surgical procedures were performed under pentobarbital sodium. We examined noxious behavioral scratching responses induced by 50 microl of 5% formalin injected subcutaneously into the vibrissa pad without any restraints. The orofacial formalin responses exhibited two distinct phases with early responses (0-10 min) and continuous prolonged responses (11-45 min). Intracisternal injection of 100 pg IL-1beta significantly increased noxious behavioral responses. Pretreatment with indomethacin, a non-selective COX inhibitor, or NS-398, a selective COX-2 inhibitor, blocked IL-1beta-induced hyperalgesic responses. However, pretreatment with SC-560, a selective COX-1 inhibitor, did not change hyperalgesic response to IL-1beta. These data suggest that central IL-1beta modulates the transmission of nociceptive information in the orofacial area and that central COX-2 plays an important role in IL-1beta-induced hyperalgesia.
Choi
H S
HS
Department of Oral Physiology, School of Dentistry, Kyungpook National University, 188-1 Samduck 2ga, Chung-gu, 700-422, Daegu, South Korea.
Lee
H J
HJ
Jung
C Y
CY
Ju
J S
JS
Park
J S
JS
Ahn
D K
DK
D000818:Animals; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D005157:Facial Pain / Q000139:chemically induced / Q000201:enzymology*; D006930:Hyperalgesia / Q000139:chemically induced / Q000201:enzymology*; D007375:Interleukin-1 / Q000633:toxicity*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007375:Interleukin-1; D007527:Isoenzymes; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases