An Ex Vivo Method for Evaluating Prostaglandin Synthetase Activity in Cortical Slices of Mouse Brain

Abstract: The release of prostaglandin E₂ (PGE₂) from cortical slices of mice into incubation medium is followed for 3 h and compared to PGE₂ levels in the corresponding slice. Immediately after decapitation, the rate of PGE₂ released into the incubation medium is elevated and a steady low rate of spontaneous release is gained within 1–2 h of incubation. PGE₂ synthesis and release is blocked in a dose‐dependent manner by either indometh‐acin (3 × 1(10⁻⁶‐ 3 × 10⁻⁴M) or flufenamic acid (2.6 × 10⁻⁶M) either when added in vitro or administered in vivo. Full recovery of PGE₂ synthesis is reached after 3 h incubation of slices following in vivo administration, of indomethacin. In vivo administration of flufenamic acid results in prolonged inhibition of PGE₂ released in vitro. The inhibition of PGE₂ released by indomethacin is also correlated with the slice PGE₂ content. Administration of lipopolysaccharide (LPS), a known activator of phospho‐lipase A₂, results in a fivefold increase in PGE₂ and a twofold increase in 6‐keto‐PGF_lQ released into the medium. The release of thromboxane B₂ is not affected by LPS.