Does PGE2 mediate Indomethacine and Theophylline effects on joint diameter and vascular response of chronically inflamed rat knee joint to saphenous nerve stimulation?

Abstract Introduction: In this study the role of PGE2 as an important inflammatory mediator in Indomethacine and Theophylline effects on joint diameter and vascular response of chronically inflamed rat knee joint to saphenous nerve stimulation was investigated. Methods: Inflammation was induced by intraarticular injection of 0.2 ml Freund,s Complete Adjuvant (FCA) and 3, 7, 14, 21 days post injection knee joint diameter, blood flow changes to saphenous nerve stimulation and PGE2 content of joint were assessed using micrometer, laser Doppler flowmeter and enzyme immunoassay kit respectively. In another three groups, control and inflamed receiving Indomethacin or Theophylline also these variables determined. Results: After inflammation induction in rat knee joint constrictory response of joint vessels to saphenous nerve stimulation reduced but joint diameter enhanced significantly. Furthermore in inflamed rats received Theophylline both vascular response of knee joint to nerve stimulation and joint diameter decreased however, daily reception of Indomethacine had no effect on joint edema but increased constrictory response of joint vessels to nerve stimulation. Furthermore PGE2 content increased in inflamed knee joint in comparison with control (uninflamed) during two weeks but in rats receiving Indomethacine it reduced significantly on days 3, 14. Also in inflamed rats treated by Theophylline PGE2 content was significantly decreased only in day 14. Conclusion: In chronic inflammation PGE2 as an inflammatory mediator play an important role in edema and modulation of constrictory response of joint vessels to nerve stimulation. Furthermore antiedematotic effect of Theophylline also may be mediated by PGE2 through decrement of vascular permeability.