The action mechanism of cyclooxygenase-2 inhibitor for treatment of experimental allergic neuritis

We previously reported the effect of a cyclooxygenase (COX)-2 inhibitor, ni mesulide, on experimental allergic neuritis (EAN) in both the induction and effector phases, in contrast to the usual COX inhibitor, which was effecti ve only when administered in the induction phase. To assess the mechanism o f action of a COX-2 inhibitor, we studied the expression of COX-2 and assay ed plasma levels of prostaglandins, and also compared the clinical effect o f a COX-2 inhibitor with a 5-lipoxygenase (LO) inhibitor, which is responsi ble for another pathway of arachidonic acid me; tabolism. Nerves of EAN rat s showed distinct expression of COX-2, which is derived mostly from endoneu rial macrophages. Treatment with a COX-2 inhibitor had no effect on its exp ression. However, prostaglandin estradiol (E-2) concentration of plasma was significantly lower compared with the control group. The LO inhibitor show ed no clinical effect. These results suggest that a selective COX-2 inhibit or is effective in the effector phase by its influence on macrophages that are responsible for nerve degeneration, (C) 1999 John Wiley & Sons, Inc.