Involvement of peripheral prostaglandins in formalin-induced nociceptive behaviours in the orofacial area of rats.
Prostaglandins (PGs) are known to be involved in the pathogenesis of inflammation and pain. However, their role in orofacial pain is not clearly understood. The present study was undertaken to determine the effect of systemic and locally administered nonsteroidal anti-inflammatory drugs (NSAIDs) on the role of PGs in orofacial pain induced by formalin in rats. The subcutaneous injection of formalin into the rat upper lip generated behavioural responses that lasted for several minutes. The orofacial responses due to formalin were seen in two distinct phases, the early response (0-3 min) and the continuous prolonged response (9-45 min). Systemic administration of ketorolac or diclofenac (10 and 30 mg/kg, i.p.) significantly attenuated formalin-induced nociceptive behaviour in the phase-2, but not in the phase-1 of the formalin test. Similarly, subcutaneous (local) administration of ketorolac or diclofenac in the orofacial area (100 and 300 microg/lip) markedly decreased the phase-2 nociceptive response due to formalin. However, both the drugs had no effect on the phase-1 response of the formalin test. These results suggest that PGs, particularly peripheral PGs are involved in nociceptive behaviour following formalin injection in the orofacial area.
Padi
S S V
SS
Pharmacology Division, University Institute of Pharmaceutical Sciences, Panjab University, 160014 Chandigarh, India.
Naidu
P S
PS
Kulkarni
S K
SK
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D001522:Behavior, Animal / Q000187:drug effects*; D004008:Diclofenac / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005157:Facial Pain / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D007274:Injections, Intraperitoneal; D007279:Injections, Subcutaneous; D020911:Ketorolac Tromethamine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D010147:Pain Measurement; D011453:Prostaglandins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D000894:Anti-Inflammatory Agents, Non-Steroidal; D011453:Prostaglandins; D004008:Diclofenac; D020911:Ketorolac Tromethamine