Postischemic production of eicosanoids in gerbil brain

The postischemic production of PGE₂, PGD₂, 6-keto-PGF_1α, and TXB₂ in brain tissue was studied in Mongolian gerbils using tissue extraction as well as a new ex vivo method. This new method permits the study of prostaglandin synthesis in slices from discrete areas of the brain (cortex, hippocampus, striatum, hypothalamus). Gerbils were sacrificed at 0, 5, and 30 minutes, and 4 and 24 hours after a 15-minute occlusion of both carotid arteries. Apart from 6-keto-PGF_1α, tissue prostaglandins determined by the extraction method were significantly increased 3 and 30 minutes after reperfusion. The most pronounced changes found by the ex vivo method were increased productions of PGD₂ immediately after reperfusion (285% in cortex, 215% in hypothalamus) and PGE₂ (350% in hippocampus, 320% in striatum) 4 hours after reperfusion. At 24 hours after reperfusion PGE₂ and PGD2 synthesis were significantly decreased by 23-70% of the values obtained from sham-operated controls. Thromboxane increased slightly in all areas after recirculation and subsequently decreased to values below the control level in striatum. The results obtained by exvivo incubation of tissue slices demonstrate that ischemia and subsequent recirculation cause site-, time-, and PG-specific changes of tissue eicosanoid production.