Participation of cyclooxygenases in cutaneous thermal nociception under non-inflamed and inflamed conditions.

Abstract

OBJECTIVE AND DESIGN:

Effects of cyclooxygenase inhibitors on noxious thermal stimuli were investigated in non-inflamed and inflamed rats.

MATERIALS:

Male Sprague-Dawley rats were used in this study.

TREATMENT:

Cyclooxygenase inhibitors, indomethacin, mofezolac, NS-398, and JTE-522 were administered orally at a dose of 10 mg/kg 1 h prior to and 4 h after the intravenous injection of lipopolysaccharide (1 mg/kg).

METHODS:

The nociceptive response was evaluated from the escape latency of foot withdrawal to the thermal stimuli with a beam of light. Expression ofcyclooxygenase was examined by reverse transcription-polymerase chain reaction.

RESULTS:

In normal rat, administration of indomethacin, relatively cyclooxygenase-1-selective inhibitor, mofezolac, or cyclooxygenase-2-selective inhibitors, NS-398 and JTE-522 had no effects on the escape latency against thermal stimuli. Injection of lipopolysaccharide into rat induced the expression of mRNA for cyclooxygenase-2 in the subcutaneous tissue of foot pad. The escape latency at 8 h was significantly shortened by the injection. This hyperalgesia could be reversed by pretreatment of rat with NS-398 or JTE-522, but not with mofezolac.

CONCLUSIONS:

Cyclooxygenases may have little participation in peripheral skin thermal nociception in non-inflamed condition, although cyclooxygenase-2 could be responsible for the hyperalgesia during inflammation induced by lipopolysaccharide.

• Authors: M Suzuki, I Hayash, Y Nara, Y Kumaga, H Okamoto, S Hoka, M Majima
• Journal: Inflammation research : official journal of the European Histamine Research Society ... [et al.] (Inflamm Res) Vol. 50 Issue 5 Pg. 283-7 (May 2001) ISSN: 1023-3830 [Print] Switzerland
• PMID: 11409492 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cyclooxygenase Inhibitors
• Lipopolysaccharides
• Prostaglandin-Endoperoxide Synthases

Topics

• Animals
• Cyclooxygenase Inhibitors (pharmacology)
• Hot Temperature
• Inflammation (chemically induced, enzymology, pathology)
• Lipopolysaccharides (pharmacology)
• Male
• Nociceptors (drug effects, physiology)
• Pain Measurement (drug effects)
• Prostaglandin-Endoperoxide Synthases (biosynthesis, physiology)
• Rats
• Rats, Sprague-Dawley
• Reverse Transcriptase Polymerase Chain Reaction
• Skin (innervation, pathology)