Prostaglandin E2 and 6-keto-prostaglandin F1α production is elevated following traumatic injury to sciatic nerve

Sciatic nerve explants cultured either alone or in the presence of peritoneal macrophages were used to study prostaglandin E-2 (PGE(2)) and 6-keto-PGF(1alpha) production following traumatic peripheral nerve injury. Although barely detectable at early time points (1-3 h in vitro), the production of PGE(2) and 6-keto-PGF(1alpha) by sciatic nerve explants increased significantly after 18 h and remained elevated for up to 96 h. The cyclooxygenase-2 (COX-2) selective inhibitor, NS-398, inhibited PGE(2) and 6-keto-PGF(1alpha) production by injured sciatic nerve in a dose-dependent manner. Consistent with the observed effect of NS-398, peripheral nerve explants, as well as Schwann cells and perineural fibroblasts cultured from neonatal sciatic nerve, each contained COX-2 immunoreactivity after 24 h in vitro. Both Schwann cells and perineural fibroblasts produced significant amounts of PGE(2) and 6-keto-PGF(1alpha); but only in the presence of arachidonic acid. As observed for injured sciatic nerve, the production of PGE(2) and 6-keto-PGF(1alpha) by primary Schwann cells and perineural fibroblasts was completely inhibited by NS-398. Compared to macrophages cultured alone, macrophages cultured in the presence of sciatic nerve explants produced large amounts of PGE2, whereas the level of 6-keto-PGF(1alpha) was unchanged. In contrast, macrophages treated with adult sciatic nerve homogenate did not produce significant amounts of either PGE(2) or 6-keto-PGF(1alpha) during the entire course of treatment. We conclude that injured sciatic nerves produce PGE(2) and 6-keto-PGF(1alpha) by a mechanism involving COX-2 activity and that macrophages produce large amounts of PGE(2) in response to soluble factors produced by injured nerve but not during the phagocytosis of peripheral nerve debris. Published 2004 Wiley-Liss, Inc.dagger.