In vivo regional levels of PGE and thromboxane in mouse brain: effect of decapitation, focused microwave fixation, and indomethacin.

A focused microwave fixation technique was tested for use in determining basal PGE and thromboxane B2 levels of mouse brain. Focused microwave irradiation (3.5 Kw/0.4 sec) to the head of C3H mice produced basal values of PGE and TXB2 which were five-fold less than those in animals killed by decapitation. Indomethacin (10 mg/kg) pretreatment blocked the decapitation rise in PGE and TXB2 levels and gave values similar to focused microwave irradiation. Indomethacin pretreatment combined with microwave fixation did not reduce PG levels more than microwave treatment alone. When microwave fixation was used, there was no difference in regional (cerebral cortex, whole cerebellum, midbrain, hypothalamus) levels of either PGE or TXB2. However, PGE levels were significantly higher than TXB2 in all regions. After decapitation there was a greater increase in TXB2 than PGE. The cerebellum produced less PGE and TXB2 after decapitation compared to the other regions. Our results confirm the usefulness of the focused microwave irradiation technique for examining in vivo basal prostaglandin levels in mouse brain.