INVOLVEMENT OF PROSTAGLANDINS PRODUCED BY CYCLOOXYGENASE-1 IN MURINE VISCERONOCICEPTION INDUCED BY PHENYLQUINONE

Intraperitoneal injection of phenyl-p-benzoquinone (phenylquinone, PQ) induced writhing in mice for up to 30 min. During this time, the peri toneal content of 6-keto-prostaglandin F-1 alpha (6-keto-PGF(1 alpha)) , a stable degradation product of PGI2, was highest in the 15-min. sam ple. In the peritoneal cells, the mRNA expression for the constitutive cyclooxygenase-1 (COX-1) was unchanged by PQ administration In contra st, Little mRNA for COX-2 was detected in the peritoneal cells from un stimulated animals, and was induced 60-120 min. after PQ administratio n. PGs involved in the induction of writhing thus seem to be derived f rom a COX-1 reaction. Oral administration of mofezolac, a non-steroida l anti-inflammatory drug which potently inhibits COX-1, suppressed the PQ-induced writhing and peritoneal accumulation of PGs.without affect ing mRNA expression for both COX isoforms in mice.